Farewell to Conti, Zloader, and Maldocs; Hello Resurrection of Raccoon Stealer, and more Ransomware Attacks

Foreword

Another quarter has passed, which means it’s time for us to share our Avast Q2/2022 Threat Report with the world. I must admit, time flies. It’s been exactly one year since we’ve started publishing these reports and this last year was everything but boring. This latest report is proof of that.

In Q2/2022, we witnessed just how quickly malware authors can adapt to changes. A few months ago Microsoft announced that it will make it difficult to run VBA macros in Office documents that were downloaded from the Internet. They backpedaled on that promise, but promised it again shortly after. Threat actors have already started preparing various alternative infection vectors, now that their beloved vector they had been using for decades is being blocked by default. For example, IcedID and Emotet have already started using LNK files, ISO or IMG images, and other tricks supported on the Windows platform as an alternative to maldocs to spread their campaigns. It’s likely you’ve already witnessed these in your inboxes.

Exploits spreading in-the-wild also made Q2/2022 interesting. For example, the Follina zero-day vulnerability in Office and Windows was widely exploited by all kinds of attackers. Our researchers also discovered and reported multiple serious zero-day exploits used by malware authors – CVE-2022-2294 affecting browsers from Google, Microsoft, and Apple. We also discovered a zero-day that Candiru exploited to get into the Windows kernel.

After months of decline, we’ve seen a significant (+24%) uptick of ransomware attacks in Q2/2022. This was partially connected to the usual ransomware suspects, but also to sudden changes happening with the Conti ransomware syndicate. Conti finally stopped its operations, but like with the mythical hydra – when you cut off a hydra’s head, two more will grow back, so we have many more ransomware groups and strains to track now. On the bright side, several new free ransomware decryptors were introduced in Q2/2022.

We participated in shutting down Zloader and witnessed the resurrection of Racoon Stealer, who’s core developer was allegedly killed in the Russian war in Ukraine. Speaking of these two countries, the malware risk ratio in these countries has stabilized, but is still higher. We also detected various malware types targeting our users in Japan, Germany, and Brazil in Q2/2022.

Fortunately, malicious cryptojacking coinminers decreased slightly in the quarter, which is good news for victims, as the energy costs are skyrocketing in many countries. And finally, I encourage you to read the mobile section where my colleagues discuss the rise and fall of the most prevalent mobile malware strains such as HiddenAds, Flubot, and SMSFactory.

Happy reading, and stay safe.

Jakub Křoustek, Malware Research Director

Methodology

This report is structured into two main sections – Desktop-related threats, where we describe our intelligence around attacks targeting the Windows, Linux, and Mac operating systems, and Mobile-related threats, where we describe the attacks focusing on the Android and iOS operating systems.

Furthermore, we use the term risk ratio in this report to describe the severity of particular threats, calculated as a monthly average of “Number of attacked users / Number of active users in a given country.” Unless stated otherwise, calculated risks are only available for countries with more than 10,000 active users per month.

Desktop-Related Threats

Advanced Persistent Threats (APTs)

Advanced Persistent Threats are typically created by nation state sponsored groups which, unlike cybercriminals, are not solely driven by financial gain. These groups pursue their nation states’ espionage agenda, which means that specific types of information, be it of geopolitical importance, intellectual property, or even information that could be used as a base for further espionage, are what they are after.

In Q2/2022, the most notable APT campaigns we observed came from the Confucius, Gadolinium/APT40, Gamaredon, and MustangPanda groups.

Confucius

Recently, we discovered a known APT group from India, Confucious, targeting Pakistani embassies in multiple countries like Brunei, Nepal, Argentina, and Azerbaijan from March to June 2022. 

The Confucious group spread their malware by sending phishing emails with PDF attachments, which contained links to phishing websites. These sites imitated official government websites which contained passwords for documents site visitors could download, these documents were malicious. This is done so that the files remain encrypted, to avert detection from static AV scanners.

We spotted malicious documents with various names related to current events, such as “VaccineStatusReport.xlsx”.

The group used documents with malicious macros to drop further infection stages written in C#. 

We also noticed several other malware families like trojan downloaders, file stealers, QuasarRAT and a custom RAT developed in C++ being dropped by the macros.

We suspect that the group may be after intelligence, based on the fact that the malware being used in their attacks is designed to spy on victims and steal files and other data. 

Gadolinium/APT40

We discovered a threat actor hosting payloads on an Australian VOIP telecommunications provider’s servers. The threat actor was abusing a zero-day remote code execution bug in Microsoft Office (CVE-2022-30190). Further analysis indicated that targets in Palau were sent malicious documents that, when opened, exploited the zero-day vulnerability, causing victims’ computers to contact the provider’s website, download and execute the malware, and subsequently become infected. Multiple stages of this attack were signed with a legitimate company certificate to add legitimacy.

When a malicious document was opened it contacted the compromised websites that hosted a first stage “Sihost.exe”, executed by msdt.exe. After execution it downloaded the second stage which was a loader. The loader was then used to download and decrypt the third stage of the attack, an encrypted file stored as ‘favicon.svg’ on the same web server. The third stage of the attack was also used to download and execute the fourth stage, which loads a shellcode from the AsyncRat malware family.

Thanks to the security community this attack was attributed to Gadolinium/APT40, a known Chinese APT group. Given a RAT was the final payload, we suspect the group may be collecting intel from its victims. 

Gamaredon

We saw a steady high volume of Gamaredon detections throughout Q2/2022, similar to what we have been observing since the start of the conflict in Ukraine in February. Gamaredon, a known Russian-backed APT group, continued using the same old toolset, as well as new powershell-based tools and their activity was still tightly focused on Ukraine.

MustangPanda

We’ve noticed multiple MustangPanda (a known Chinese APT group) campaigns running in parallel during Q2/2022 in multiple locations, including Philippines, Myanmar, Thailand, Singapore, Mongolia, and India, as well as in other, new regions the group previously hadn’t been present in. All of these campaigns utilized DLL sideloading for payload delivery, for which the group continued using well known abused binaries, similarly to their previous campaigns, but they also added a few new ones to their arsenal. 

Based on the language and content of the phishing documents they used, the group expanded their activities in Europe e.g. Baltic countries, as well as in South America. The main malware strain being used for the initial infection was still Korplug RAT.

Luigino Camastra, Malware Researcher
Igor Morgenstern, Malware Researcher
Jan Holman, Malware Researcher

Adware

Desktop adware has slowed down this quarter compared to Q1/2022, as the graph below illustrates:

We have monitored a noticeable decrease in risk ratio for users in Africa, the Balkans, the Middle East, and Southeast Asia. On the other hand, there was an increase in risk ratio for users in South America, parts of Europe, and Central Asia; namely, Brazil, Austria, Germany, Switzerland, Tajikistan, and Uzbekistan; see the map below.

In Q1/2022, we observed considerable adware activity in Japan that returned to its average level in Q2/2022. On the contrary, there was a rise in adware activity in Austria and Switzerland, as illustrated in the chart below.

The common denominator for both countries is Revizer adware, which is usually dropped by other malware or free applications. Revizer adware monitors users’ actions on specific sites and updates their content without users’ consent or permission. The adware typically injects unwanted banners on websites the victim visits, rewrites the default home page of browsers, and defines web page text being updated to hyperlinks that lead to unwanted or malicious content.

As in Q1/2022, 65% of adware we saw was from various adware families. The clearly identified strains of Windows adware are: RelevantKnowledge, Cryxos, OpenCandy, MultiPlug, Revizer, and ICLoader. The most viewed adware for MacOS are as follows: MacOS:Bundlore, MacOS:Adload, MacOS:Spigot, MacOS:MaxOfferDeal.

Martin Chlumecký, Malware Researcher
Vladimír Žalud, Malware Analyst

Bots

Emotet developers are keeping up with the times and, as many other projects do, started supporting the 64-bit architecture. Emotet’s 32-bit binaries are no longer distributed. There have also been some minor changes in their backend workflow. While previously, we could have expected to receive the fingerprinting module only once, just after the registration, we are receiving it with every request now. The module’s distribution has also changed a bit. In the past, we would see a new file size quite regularly, now the file size seems to remain stable. However, Emotet samples themselves have gotten bigger, after having a quick look, this was due to Nirsoft’s Mail PassView being included in these new samples.

Perhaps the most noticeable change in botnet behavior was spurred by Microsoft’s announcement that it will be significantly harder to execute VBA macros in documents downloaded from the internet. Since malicious documents are one of the most popular infection vectors, spambots had to react. We have already observed cybercriminals using alternative attack vectors, such as LNK files linking to malicious resources on the internet. Some of the new substitutes are rather unusual. For example, ISO and IMG files are usually images of optical discs and hard drives (or SSDs), but they are now being used as archives instead. Newer versions of Microsoft Windows provide a native way of mounting these images. They have therefore become a viable alternative to maldocs. There are also a few added benefits to using ISO images, such as using hidden files so they can, for instance, use LNK files without needing to rely on remote resources.

In Q2/2022, authorities from the United States, Germany, the Netherlands, and the United Kingdom claim to have dismantled the RSOCKS botnet. This botnet consisted of millions of hacked devices that were rented as proxies to anyone wanting to route their traffic through these devices. Only the botnet was disrupted, so the owner may still try to rebrand and relaunch his/her operation. This theory is supported by a post from Rsocks account on BlackHatWorld forum that informs about RSocks’ end of existence and about a transfer of all active plans, and fund balances to another service which is yet to be announced.

While the development of many botnets was rather turbulent, the landscape itself and the risk ratio remained rather stable. The most significant increase in risk ratio was in Brazil, where users had an approximately 35% higher chance of encountering this kind of malware attack compared to Q1/2022. In contrast to the previous quarter, the risk ratio has almost stabilized in Russia and Ukraine.

In terms of the war in Ukraine, we are still seeing attacks associated with the conflict, usually as a retaliatory action; for instance, attacks targeting Lithuanian infrastructure after imposing a partial goods blockade on Kaliningrad. On the other hand, we have observed a decline in websites that include code to use site visitors’ computers to carry out DDoS on Russian infrastructure. Nevertheless, it is still too soon to declare complete “professionalization” of attacks. After the aforementioned attacks on the Lithuanian infrastructure, It should not be much of a surprise that Ukrainian Telegram channels organizing cyber-vigilantes are also still active and new DDoS target lists are being distributed.

We have seen a significant decline in several botnet showrunners, notably Emotet, Phorpiex, Ursnif, and MyloBot. On the other hand, Qakbot, SDBot, and Amadey have seen rather significant increases in their market share. The most common bots we are seeing are:

• Emotet
• Amadey
• Phorpiex
• MyKings
• Qakbot
• Nitol
• Tofsee

Adolf Středa, Malware Researcher

Coinminers

With the energy crisis on our shoulders and electricity bills reaching new heights, coinminers can cause more harm than ever before. Fortunately, in comparison to the previous quarter, there was quite a big decline in the overall coinmining activities during Q2/2022, -17% of risk ratio in total. This is further underlined by the fact that cryptocurrencies are at their long term lows, turning the return of investment less attractive for the attackers.

Even though the number of overall attacks decreased, we did observe users in some countries being targeted more than others, including Madagascar with a 9.12% risk ratio (+57% Q2/2022 vs. Q1/2022). Based on our telemetry, this is due to the increased NeoScrypt activity in the region. The second most impacted country is Serbia with a 7.16% risk ratio (+25% Q2/2022 vs. Q1/2022) where we saw web miners used more often.

The leading trend continues to be web miners. These miners are commonly used as a substitute, or on top of ads on websites, to further monetize site owners’ profits, and are usually completely hidden and run without any users’ consent.

The notorious XMRig is still leading the murky waters of executable miners, being it used as a standalone application or ultimately hidden as the final payload of the vast constellation of droppers, mining worms, or configured as a dedicated module of information stealers and other monetary-focused malware.

The most common coinminers in Q2/2022 were:

• Web miners (various strains)
• XMRig
• CoinBitMiner
• NeoScrypt
• CoinHelper

At this point, we would like to remind our readers about the distinction between mining tools and mining malware. If you are interested in learning the difference between the two, please read our guidelines.

Jan Rubín, Malware Researcher

Information Stealers

Two important things happened in Q2/2022: The first is the shutdown of Zloader at the end of March. The second is the release of the version 2.0 of Raccoon Stealer in May. 

Despite this, Q2/2022 didn’t bring much change in the overall numbers. The trend is just slightly increasing, following the previous quarter.

Targeted regions also didn’t change much, the number of users we protected in countries around the world only changed slightly compared to the previous quarter. The only notable change happened in Angola, where the risk ratio dropped (-18%) mostly due to a decline in Fareit infections.

The most common information stealers in Q2/2022 were:

• FormBook
• Lokibot
• AgentTesla
• Fareit
• RedLine
• VIPSpace

Return of Raccoon Stealer

Raccoon Stealer is a popular information stealer that has been around since 2019. It is capable of stealing various data, including cookies, and cryptowallet files. The actors behind Raccoon Stealer use the Telegram infrastructure to deliver actual C&C addresses to bots. You can read our in-depth technical analysis of Raccoon Stealer here.

In March 2022, the development and spreading of Raccoon Stealer was paused: a team member allegedly died during the war in Ukraine:

However, we started to see new samples of Raccoon Stealer in May 2022, indicating the beginning of the group’s new era. Shortly after, in late June 2022, the group made an announcement that Raccoon Stealer 2.0 is ready and released and that the group is back in business.

Interestingly, the new version is much simpler and smaller. The malware’s authors didn’t use any traffic encryption, C&Cs are hardcoded in the samples, responses from C&C servers are no longer in JSON format, and more features that were included in version 1.0 are missing.

Zloader Shutdown

Zloader was an infamous banker with a wide range of capabilities: it was able to download and execute other malware, steal cookies and cryptowallet files. It was also able to inject arbitrary code in HTML pages to steal money from online banking systems. 

Our mission is to protect digital freedom, and in order to do so, we need to go after the bad guys who threaten that freedom. At the end of March 2022, after months of cooperating with Microsoft and other major players from the security industry, our analysis of Zloader played a role in taking down the Zloader infrastructure. A Zloader team member was also identified as a result of the investigations. We haven’t seen any new Zloader C&C activities since. 

During our analysis of Zloader, we discovered links to other malware: Raccoon Stealer and Ursnif. Two out of three Zloader download tasks contained links to Raccoon Stealer, they used the same configuration. Furthermore, Raccoon Stealer was mentioned in an analysis published by Checkpoint before we received commands from C&Cs, which included links to Raccoon Stealer. A bigger surprise to us was when we found Zloader samples and Ursnif samples signed with the same digital signature. This leads us to believe that the group behind Zloader is either working with the groups behind Raccoon Stealer and Ursnif or purchased and applied their products.

Jan Rubín, Malware Researcher
Vladimir Martyanov, Malware Researcher

Ransomware

For those who read our previous Threat Reports (Q1/2022, Q4/2021, etc.), you may recall that the volume of ransomware attacks had been declining over the past few quarters. This was most likely a result of several busts and takedowns, Russian officials persecuting ransomware-gangs, and other impactful actions carried out by law enforcement. The bad news is that this is no longer the case in Q2/2022. We’ve witnessed a significant increase of ransomware attacks: +24% globally compared to Q1/2022. Clearly, ransomware is not going away this year.

The countries in which users are most at risk of encountering ransomware are:

• Yemen (0.53% risk ratio)
• Egypt (0.41%)
• Algeria (0.37%)
• Vietnam (0.32%)

The highest Q/Q increases in ransomware risk ratio occurred in Argentina (+56%), UK (+55%), Brazil (+50%), France (+42%), and India (+37%).

The most prevalent ransomware samples in Q2/2022 were:

• STOP
• WannaCry
• Conti (and its successors)
• Lockbit
• Thanatos
• HiddenTear variants
• CrySiS
• Cryakl

It’s well known that the ransomware business is based on blackmailing – the cybercriminals render data inaccessible in the hopes that victims pay to get their data back. The process, however, is, unfortunately, not that straightforward. According to a recent survey conducted by Venafi, 35% of victims paid the ransom, but were still unable to retrieve their data. This is a good reminder that there is no guarantee that upon paying the ransom, victims get their data back. Please, backup your data regularly – so that if you fall for ransomware, you are not pressured into paying a ransom fee to get your data back!

To protect your computer or company’s network even further, make sure you regularly update your PC – the operating system, your antivirus, and even the applications you are using. According to our fellow security researchers at Group-IB, ransomware gangs are relying on existing vulnerabilities more and more, exploiting them to get their ransomware onto devices. According to the joint report by Cyber Security Works, Securin, Cyware and Ivanti, there was a 6.8% increase in vulnerabilities actively exploited by ransomware (Q1/2022 vs. Q4/2021), and there are now 157 vulnerabilities actively being exploited by ransomware operators. 

Luckily, ransomware developers are humans too, so they can make mistakes when developing their “products”. One such example is the TaRRaK ransomware which we successfully analyzed, and found a weakness in its encryption schema. This allowed us to release a free decryption tool for the ransomware in June.

Related to the same topic, a legitimate company can improve its product by announcing a bug bounty – an open contest, challenging everyone to find bugs in its product and giving rewards for it. Ransomware developers do the same. The authors of LockBit 3.0 announced a bug-bounty challenge, paying for bugs found in their website, encryption and even paying people who deliver good ideas to the ransomware gang.

On the bright side, the operators behind the AstraLocker ransomware announced that they are shutting down their business and moving on to the area of crypto-jacking. As part of the shutdown, a ZIP file with decryptors was published. Anyone who fell victim to this ransomware in the past, can therefore now decrypt their data without paying the ransom.

In our previous report, we described the latest development around the Sodinokibi / REvil ransomware. After the arrest of some of the gang members at the end of 2021, and the decline of the ransomware samples, things changed a bit  in Q2/2022. On April 7th, Russian news agency TASS reported that “Washington announced that it unilaterally shut down the communication channel on cybersecurity with Moscow”. Shortly after this, on April 19th, REvil’s TOR sites were back online and a new ransomware operation began. Two weeks later, new ransomware samples started to appear. It seemed that REvil was back at that moment, but luckily pretty much nothing related to REvil has happened since. Let’s hope it will stay the same.

But Sodinokibi/REvil was not the only ransomware group with ties to Russia…

Conti

The first public mention of victims of the new Conti ransomware dates back to 2019. However, it was not entirely new, it was a continuation of the Ryuk ransomware from 2018, which had ties to the Hermes ransomware from 2017. Over time, Conti transformed from a small ransomware group to a ransomware syndicate, and it was in the news spotlight many times in Q2/2022. 

We’ve previously reported about a breach of Conti’s infrastructure by a Ukrainian security researcher leading to a leak of their source-codes and internal communications. Conti, which collected more than 150 million USD in ransom, as of January 2022, based on estimates from the US Department of State, resumed its operations and continued targeting dozens of organizations. Moreover, in Q2/2022, Conti targeted 27 Costa Rican government bodies in Q2/2022, causing the country to declare a national state of emergency. A second wave of attacks targeting the country’s healthcare was carried out using HIVE, a ransomware-as-a-service which Conti has ties to. Our telemetry reveals Costa Rica as the fourth highest country in terms of risk ratio (+101% increase, compared to Q1/2022). 

Conti’s resurrection was short-lived, and ended in June when their operations were shut down by its authors. We believe it was a result of multiple factors, including the aforementioned leak, unwanted attention, revealed connection to Russia, and complications with victim payments, because these may be violating U.S. economic sanctions on Russia.

Unfortunately, the end of one malware threat rarely means peace and quiet, and this especially applies to ransomware. The end of the Conti syndicate may lead to hundreds of cybercriminals moving to work with other groups, such as Hive, BlackCat, or Quantum, or them working on new ransomware “brands”, e.g. Black Basta or Karakurt. Let’s see how the Conti story will continue in Q3/2022…

Jakub Křoustek, Malware Research Director
Ladislav Zezula, Malware Researcher

Remote Access Trojans (RATs)

Same year, new quarter and similar level of RAT activity. This quarter’s RAT activity was inline with what we are used to seeing, although spiced up by the appearance of some previously unseen RATs. We can speculate that the activity is going to slightly decrease in the summer.

The most affected countries in Q2/2022 were Papua New Guinea, Yemen and Turkmenistan. There was a drop in RAT activity in countries involved in the ongoing war in Ukraine, with risk ratios dropping by -26% in the Ukraine, compared to Q1/2022, and -43% in Russia, and -33% in Belarus. This might suggest a bit of slowing down after the initial wave of attacks we reported in our last report. On the other hand, we’ve seen a huge increase in RAT attacks in Japan (+63%), due to AsyncRat, and in Germany (+28%), mainly due to Netwire.

The most prevalent RATs based on our telemetry in this quarter were:

• njRAT
• Warzone
• AsyncRat
• Remcos
• NanoCore
• NetWire
• HWorm
• QuasarRAT
• LuminosityLink
• FlawedAmmyy

While njRAT and Warzone are steadily leading the bunch, there has been a change in the third spot. AsyncRat moved up by one place. One of the reasons for this change might be because the Follina vulnerability (CVE 2022-30190) was used to distribute this RAT, as we reported in June.

Other RATs whose prevalence increased considerably in Q2/2022:

• BlackNix
• VanillaRAT
• HWorm
• Borat

HWorm is a RAT written in JavaScript, we saw a big increase in detections, causing the RAT to make it into the top 10 most prevalent RATs this quarter. HWorm was mostly active in Africa and Central Asia.

The Borat RAT, which appeared in Q1/2022, is steadily gaining a foothold amongst its competition. It made the news again when its source code leaked. It turned out it was a decompiled code and not the original source code, nevertheless this leak might still lead to derivatives appearing.

In May, we tweeted about a campaign targeting Unicredit bank in Italy which made use of a slightly modified version of HorusEyes. HorusEyes is a RAT, publicly available on GitHub.

In our Q1/2022 report, we closed our RAT section mentioning two new RATs written in Go. In Q2/2022, there was at least one new addition, the Nerbian RAT. Nerbian is usually delivered via phishing emails with Microsoft Office attachments containing macros. The macro executes a downloader, which deploys the RAT payload on victims’ computers. The set of features included is fairly common as you would expect in a modern RAT, including logging keystrokes, capturing screen etc.

We have also spotted malware which seems to be a crossover between a bot and a RAT named MSIL/Bobik, being used to carry out DDoS attacks. Its features also include manipulating files and exfiltrating them from victim systems, deploying additional malware, stealing credentials etc. We tweeted some of its targets, which seem to be pro Ukraine targeting companies and governments supporting Ukraine.

APT group GALLIUM, likely a Chinese state-sponsored group, was seen using a new remote access trojan named PingPull as reported by Palo Alto Networks Unit 42. PingPull can make use of three protocols to facilitate communication with its command and control server (ICMP, HTTP, and raw TCP). It tries to hide as “Iph1psvc” service mimicking the legitimate IP Helper service, including taking on its name and description. The functions available include manipulating files, enumerating drives and running commands on victim system.

At the end of June, we observed a new campaign delivering the AgentTesla RAT to potential victims in Czech Republic and Hungary, using phishing emails as an entry point. The emails claim confirmation of an unspecified check is needed, referring to a previous phone call (that never happened) in order to trick recipients into opening the attachment.

There was another piece of news regarding AgentTesla: A group of three suspected global scammers from Nigeria were arrested according to INTERPOL. They used AgentTesla to access business computers and divert monetary transactions to their own accounts.

The last days of this quarter brought news of ZuoRAT targeting SOHO routers, as reported by Lumen. This RAT allows attackers to pivot into the local network and to make connected devices install additional malware.

Ondřej Mokoš, Malware Researcher

Rootkits

In Q2/2022, rootkit activity remained on the same level as the previous quarter, as illustrated in the chart below. A little surprise is a relatively stable trend this quarter, despite the many campaigns that we have observed, as campaigns usually cause peaks in trends.

In our previous quarterly report, we introduced the rising trend of r77-Rootkit (R77RK), representing 37% of all identified rootkits. This trend continued in Q2/2022, and R77RK represented more than 57% of the rootkits we detected. We also monitored the activity of R77RK in its GitHub repository, and it is evident that the rootkit development is still active within several new branches. Consequently, R77RK has become the major rootkit since its trend copies the overall rootkit trend in Q2/2022, as the graph below demonstrates.

This phenomenon can explain the stable trend, as integrating R77RK into any malware is easy thanks to the excellent rootkit documentation. Therefore, malware authors have started to abuse this rootkit more frequently.

The map below animates that China is still the most at-risk country in terms of all the users we protected from rootkits in general, and R77RK has spread to South America, Africa, East Europe, and Southwest Asia.

In comparison to Q1/2022, the risk ratio has increased for users in the following countries: Brazil, Ukraine, Colombia, and Italy. On the other hand, the risk ratio decreased for users in Taiwan, Malaysia, and China.

In summary, China remains the country in which users have the highest risk of encountering a rootkit, and the activity seems uniform due to the increasing dominance of R77RK. We will have to wait till Q3/2022 to see whether or not R77RK is still the most prevalent rootkit in the wild.

We also published an analysis of a new evasive Linux malware known as Syslogk we discovered. Even if other open source kernel rootkits (e.g. Reptile) are clearly more prevalent Linux threats, we noticed that more stealthy Linux malware is being developed (e.g. Symbiote and OrBit). Let’s see if cybercriminals will continue to target Linux servers next quarter.

Martin Chlumecký, Malware Researcher
David Àlvarez, Malware Researcher

Technical support scams

It appears the scammers behind tech support scams (TSS) are taking a break to enjoy the summer weather, as there were no big spikes in TSS activity in Q2/2022. In May, we saw a 12% drop in comparison to the previous month. This drop can be  partially due to the INTERPOL operation against social engineering scammers. According to the report, many call centers worldwide were raided by the police in an attempt to clampdown on organized crime.

The top affected countries are still the same as in Q1/2022, but it looks like there was a slight increase in TSS activity in risk ratio in Japan (+2,35%) as well as Germany (+0,98%) in Q2/2022, compared to Q1/2022

In Q2/2022, we registered hundreds of unique telephone numbers used in TSS scams. Here are the top 20 phone numbers:

1-888-845-1636	1-833-987-2752
1-888-520-2539	1-888-788-7144
1-855-568-2875	1-888-909-8613
1-888-731-1647	1-866-498-0028
1-888-503-8316	1-844-563-1918
1-888-474-3849	1-855-568-2877
1-855-485-2901	1-844-697-0039
1-866-603-0648	1-888-608-2514
1-844-793-8999	1-844-580-1408
1-888-660-0513	1-855-484-1999

Alexej Savčin, Malware Analyst

Vulnerabilities and Exploits

Q2/2022 surprised us with the return of Candiru. This notorious spyware vendor came back with an updated toolset and fresh zero-day exploits. We managed to capture two zero-days used by Candiru, and discovered evidence suggesting that they have at least one more zero-day at their disposal. 

The first zero-day we found abused a bug in WebRTC (CVE-2022-2294) and was exploited to attack Google Chrome users in highly targeted watering hole attacks. As the bug was located in WebRTC, it affected not only Google Chrome, but also many other browsers. As a result, Google, Microsoft, and Apple all had to patch their respective browsers. This WebRTC vulnerability allowed Candiru to achieve remote code execution (RCE) in a sandboxed renderer process. A second zero-day exploit was needed to escape the sandbox. Unfortunately, Candiru was serious about protecting its zero-days against threat hunters like us, so the nature of the sandbox escape exploit remains a mystery for now. 

A third zero-day that Candiru exploited to get into the Windows kernel, on the other hand, did not remain a mystery to us. This was a vulnerability in a third-party signed driver that Candiru smuggled onto their target’s machine, BYOVD style. This vulnerability was a textbook example of a common vulnerability class, where a driver exposes IOCTLs that let attackers directly access physical memory.

In other vulnerability news, the Follina zero-day (discovered in the wild by nao_sec in May) was widely exploited by all kinds of attackers, ranging from common opportunistic cybercriminals to Russia-linked APTs operating in Ukraine. Interestingly, we also discovered an outbreak of Follina targeting Palau, an enchanting tiny archipelago in Micronesia. 

Follina remained unpatched for quite a while which, combined with the ease of exploitation, made it a very serious threat. Follina was mostly exploited through Microsoft Office documents, where it could execute arbitrary code even without the victim having to enable macros. This relates to another factor that might have contributed to Follina’s popularity: Microsoft’s decision to block macros by default. While Microsoft seemed to be unsure about this decision, rolling it back shortly after announcing because of “user feedback”, the latest decision is to block macros from untrusted sources by default. We hope it stays that way.

The most frequently used exploit for MacOS was MacOS:CVE-2019-6225 in Q2/2022. This memory corruption issue was available for MacOS, iOS, and tvOS and malware strains were using those to elevate privileges. Furthermore, MacOS:CVE-2022-26766 was also prevalent as it was available for tvOS, iOS iPadOS, macOS, and watchOS. The software did not validate a certificate. Malicious apps were thus able to bypass signature validation.

Jan Vojtěšek, Malware Reseracher

Web skimming 

In Q2/2022 we observed several malicious domains that served skimmer code for months without being taken down. For example, we have been detecting fraudlabpros[.]at since February 2022 and it is still active and serving heavily obfuscated malicious skimmer code.

The code below was found on the infected e-commerce site pricelulu[.]co[.]uk. Malicious actors continuously use the same technique: They pretend to load a script from googletagmanager.com, but instead malicious Javascript from //fraudlabpros[.]at/jquery.min.js?hash=a7214c982403084a1681dd6 is loaded.

Another domain that is still active and has been used since at least February is segtic[.]com, it resolves to IP 54.39.48.95 from 2020-09-29. It is connected to jqueryllc[.]net that was used in malicious code as an exfiltration domain for payment details.

The most common content detection in Q2/2022 was a skimmer that mostly attacks Magento websites. This skimmer exploits compromised third party websites to exfiltrate payment details. The pattern for exfiltration details was the same every time – <breached_website>/pub/health_check.php. In some cases the skimmer was simple 50 line code, in other cases, the skimmer inserted its own payment form on the compromised website and the payment details were custom encoded before exfiltration.

This quarter,  we saw an increase in web skimmer activity in Serbia, caused by the malicious domain yoursafepayments[.]com, which infected the e-commerce website planetbike[.]rs. The malicious domain is the same one used in the attack on Philco Brazil in February that we tweeted about. Several e-commerce websites around the world have been infected with this malicious domain and attackers have also used other filenames that contain malicious code (des.css, back.css, text.css, s.css), not just fonts.css.

Overall, web skimming attacks are still prevalent and in many cases they remain on infected websites for a long time.

Pavlína Kopecká, Malware Analyst

Mobile Threats

Adware

As with last quarter, adware clearly dominates the mobile threat landscape, as has been the case for the last few years. While not necessarily as malicious as other Android threats, adware has a significant negative impact on the user experience with intrusive advertisements that can permeate the entire device, often paired with stealth features to avoid discovery.

Strains such as HiddenAds and FakeAdblockers use overlays that go on top of the user’s intended activity, creating pop ups that hassle and frustrate the user when using the infected device. Another common feature used in strains such as MobiDash is to delay adware activity by several days to fool the user into thinking it may be caused by another app. Coupled with stealth features such as hiding their own app icon and name, the Adware’s may become fairly difficult for the user to identify.

While the Google Play Store has been a favorite method of delivery, repackaged games and applications are increasingly being bundled with adware. Users are advised to avoid unofficial app sources to prevent adware infection, and to check reviews as well as permissions on official app stores. Adware is often disguised as games, QR code scanners, camera filters and photo editing apps among others.

Asia, the Middle East, and South America continue to be the regions most affected by mobile adware, as shown in the map below. Brazil, India, Argentina, and Mexico hold the top spots, however we saw a 33% decrease in protected users on average when compared to last quarter in these countries. On the other hand, the US holds fifth place where we see a 15% uptick in protected users. Despite these shifts, adware is and continues to be a persistent threat and annoyance to users worldwide.

Bankers

Q2/2022 was eventful in the mobile banker malware domain. While Cerberus/Alien holds the top spot for most users protected, Hydra has again been surpassed by Flubot for second place. This is despite the news that the Flubot group has been disbanded by Europol in May. Avast observed a large SMS phishing campaign in several European countries just prior to the takedown. It remains to be seen what effect Flubot’s takedown will have on the overall Banker sphere.

Infection vectors for bankers appear to remain largely the same, relying on fake delivery messages, voicemails and similar. These masquerading techniques appear to yield results as reflected in the continuously high numbers of protected users. Unfortunately, we have observed that infected devices are often used to further spread banker malware via SMS and other messaging services, contributing to the high numbers.

Taking into account Flubot’s takedown in May, as well as other disruptions to its spread in last quarter, we see a steady decrease in the number of protected users from last quarter. We have dipped below the numbers prior to Flubot’s entry into the market back in April 2021.

In Q2/2022 Spain, Turkey and Australia are again the most targeted markets, as has been the case for several quarters now, despite an average of 24% less protected users when compared to last quarter. Interestingly, France and Japan are also among the top affected countries, where despite the downward trend of banker attacks, we see a 12% increase in protected users.

TrojanSMS

As reported in Q1/2022, a new wave of premium subscription-related scams was unleashed on Android users. UltimaSMS, GriftHorse and Darkherring malware strains caused significant hassle and financial losses to users worldwide. Continuing the trend of SMS focused malware, we are seeing a big uptick in users protected from a newly discovered strain of TrojanSMS, SMSFactory, taking the top spot in Q2/2022, followed by DarkHerring.

SMSFactory takes a different approach when compared to the previous premium SMS subscription malwares. Instead of subscribing victims to premium services, it sends SMS messages to premium numbers to extract money from its victims. Unlike UltimaSMS or others that used the Play Store as an infection vector, SMSFactory is spreading through pop ups, redirects and fake app stores. It has gathered a considerable number of victims in a short span of time. With its stealth features, such as hiding its icon and not having an app name, it may prove difficult to identify and remove, causing havoc on the victim’s phone bill.

There is a notable shift in focus, mainly due to SMSFactory’s worldwide spread. Brazil, Russia and Germany have the highest number of protected users, while Iraq, Azerbaijan and Haiti have the highest risk numbers. It is clear SMSFactory takes a different and effective approach to its spread and it is reflected in the high numbers of protected users.

The quarterly Q2/2022 graph shows a steady increase, mainly due to SMSFactory and its new versions popping up later in the quarter. We expect this trend to continue into the next quarter.

Jakub Vávra, Malware Analyst

Acknowledgements / Credits

The post Avast Q2/2022 Threat Report appeared first on Avast Threat Labs.

The TaRRaK ransomware appeared in June of 2021. This ransomware contains many coding errors, so we decided to publish a small blog about them. Samples of this ransomware were spotted in our user base, so we also created a decryptor for this ransomware.

Skip to instructions on how to use the TaRRaK decryptor.

Behavior of the ransomware

The ransomware is written in .NET. The binary is very clean and contains no protections or obfuscations. When executed, the sample creates a mutex named TaRRaK in order to ensure that only one instance of the malware is executed. Also, an auto-start registry entry is created in order to execute the ransomware on every user login:

The ransomware contains a list of 178 file types (extensions) that, when found, are encrypted:

The ransomware avoids folders containing one the following strings:

• All Users\Microsoft\
• $Recycle.Bin
• :\Windows
• \Program Files
• Temporary Internet Files
• \Local\Microsoft\
• :\ProgramData\

Encrypted files are given a new extension .TaRRaK. They also contain the TaRRaK signature at the beginning of the encrypted file:

File Encryption

Implementation of the encryption is a nice example of a buggy code:

First, the ransomware attempts to read the entire file to memory using File.ReadAllBytes(). This function has an internal limit – a maximum of 2 GB of data can be loaded. In case the file is larger, the function throws an exception, which is then handled by the try-catch block. Unfortunately, the try-catch block only handles a permission-denied condition. So it adds an ACL entry granting full access to everyone and retries the read data operation. In case of any other error (read failure, sharing violation, out of memory, read from an offline file), the exception is raised again and the ransomware is stuck in an infinite loop.

Even if the data load operation succeeds and the file data can be fit in memory, there’s another catch. The Encrypt function converts the array of bytes to an array of 32-bit integers:

So it allocates another block of memory with the same size as the file size. It then performs an encryption operation, using a custom encryption algorithm. Encrypted Uint32 array is converted to another array of bytes and written to the file. So in addition to the memory allocation for the original file data, two extra blocks are allocated. If any of the memory allocations fails, it throws an exception and the ransomware is again stuck in an infinite loop.

In the rare case when the encryption process finishes (no sharing violation or another error), the ransom note file named Encrypted Files by TaRRaK.txt is dropped to the root folder of each drive:

Files with the .TaRRaK extension are associated with their own icon:

Finally, desktop wallpaper is set to the following bitmap:

How to use the Avast decryptor to decrypt files encrypted by TaRRaK Ransomware

To decrypt your files, follow these steps:

1. You must be logged to the same user account like the one under which the files were encrypted.
2. Download the free Avast decryptor for 32-bit or 64-bit Windows.
3. Run the executable file. It starts in the form of a wizard, which leads you through the configuration of the decryption process.
4. On the initial page, you can read the license information, if you want, but you really only need to click “Next”

5. On the next page, select the list of locations you want to be searched and decrypted. By default, it contains a list of all local drives:
   

6. On the final page, you can opt-in to backup encrypted files. These backups may help if anything goes wrong during the decryption process. This option is turned on by default, which we recommend. After clicking “Decrypt”, the decryption process begins. Let the decryptor work and wait until it finishes decrypting all of your files.
   

IOCs

SHA256
00965b787655b23fa32ef2154d64ee9e4e505a42d70f5bb92d08d41467fb813d
47554d3ac4f61e223123845663c886b42016b4107e285b7da6a823c2f5050b86
aafa0f4d3106755e7e261d337d792d3c34fc820872fd6d1aade77b904762d212
af760d272c64a9258fab7f0f80aa2bba2a685772c79b1dec2ebf6f3b6738c823

The post Decrypted: TaRRaK Ransomware appeared first on Avast Threat Labs.

Cyberwarfare between Ukraine and Russia

Foreword

The first quarter of 2022 is over, so we are here again to share insights into the threat landscape and what we’ve seen in the wild. Under normal circumstances, I would probably highlight mobile spyware related to the Beijing 2022 Winter Olympics, yet another critical Java vulnerability (Spring4Shell), or perhaps how long it took malware authors to get back from their Winter holidays to their regular operations. Unfortunately, however, all of this was overshadowed by Russia’s war in Ukraine.

Similar to what’s happening in Ukraine, the warfare co-occurring in cyberspace is also very intensive, with a wide range of offensive arsenal in use. To name a few, we witnessed multiple Russia-attributed APT groups attacking Ukraine (using a series of wiping malware and ransomware, a massive uptick of Gamaredon APT toolkit activity, and satellite internet connections were disrupted). In addition, hacktivism, DDoS attacks on government sites, or data leaks are ongoing daily on all sides of the conflict. Furthermore, some of the malware authors and operators were directly affected by the war, such as the alleged death of the Raccoon Stealer leading developer, which resulted in (at least temporary) discontinuation of this particular threat. Additionally, some malware gangs have chosen the sides in this conflict and have started threatening the others. One such example is the Conti gang that promised ransomware retaliation for cyberattacks against Russia. You can find more details about this story in this report.

With all that said, it is hardly surprising to say that we’ve seen a significant increase of attacks of particular malware types in countries involved in this conflict in Q1/2022; for example, +50% of RAT attacks were blocked in Ukraine, Russia, and Belarus, +30% for botnets, and +20% for info stealers. To help the victims of these attacks, we developed and released multiple free ransomware decryption tools, including one for the HermeticRansom that we discovered in Ukraine just a few hours before the invasion started.

Out of the other malware-related Q1/2022 news: the groups behind Emotet and Trickbot appeared to be working closely together, resurrecting Trickbot infected computers by moving them under Emotet control and deprecating Trickbot afterward. Furthermore, this report describes massive info-stealing campaigns in Latin America, large adware campaigns in Japan, and technical support scams spreading in the US and Canada. Finally, again, the Lapsus$ hacking group emerged with breaches in big tech companies, including Microsoft, Nvidia, and Samsung, but hopefully also disappeared after multiple arrests of its members in March.

Last but not least, we’ve published our discovery of the latest Parrot Traffic Direction System (TDS) campaign that has emerged in recent months and is reaching users from around the world. This TDS has infected various web servers hosting more than 16,500 websites.

Stay safe and enjoy reading this report.

Jakub Křoustek, Malware Research Director

Methodology

This report is structured into two main sections – Desktop-related threats, informing about our intelligence on attacks targeting Windows, Linux, and macOS, and Mobile-related threats, where we advise about Android and iOS attacks.

Furthermore, we use the term risk ratio in this report to describe the severity of particular threats, calculated as a monthly average of “Number of attacked users / Number of active users in a given country.” Unless stated otherwise, calculated risks are only available for countries with more than 10,000 active users per month.

Desktop-Related Threats

Advanced Persistent Threats (APTs)

In March, we wrote about an APT campaign targeting betting companies in Taiwan, the Philippines, and Hong Kong that we called Operation Dragon Castling. The attacker, a Chinese-speaking group, leveraged two different ways to gain a foothold in the targeted devices – an infected installer sent in a phishing email and a newly identified vulnerability in the WPS Office updater (CVE-2022-24934). After successful infection, the malware used a diverse set of plugins to achieve privilege escalation, persistence, keylogging, and backdoor access.

Furthermore, on February 23rd, a day before Russia started its invasion of Ukraine, ESET tweeted that they discovered a new data wiper called HermeticWiper. The attacker’s motivation was to destroy and maximize damage to the infected system. It’s not just disrupting the MBR but also destroying a filesystem and individual files. Shortly after that, we at Avast discovered a related piece of ransomware that we called HermeticRansom. You can find more on this topic in the Ransomware section below. These attacks are believed to have been carried out by Russian APT groups.  

Continuing this subject, Gamaredon is known as the most active Russia-backed APT group targeting Ukraine. We see the standard high level of activity of this APT group in Ukraine which accelerated rapidly since the beginning of the Russian invasion at the end of February when the number of their attacks grew several times over.

We also noticed an increase in Korplug activity which expanded its focus from the more usual south Asian countries such as Myanmar, Vietnam, or Thailand to Papua New Guinea and Africa. The most affected African countries are Ghana, Uganda and Nigeria. As Korplug is commonly attributed to Chinese APT groups, this new expansion aligns with their long-term interest in countries involved in China’s Belt and Road initiative.

Luigino Camastra, Malware Researcher
Igor Morgenstern, Malware Researcher
Jan Holman, Malware Researcher

Adware

Desktop adware has become more aggressive in Q4/21, and a similar trend persists in Q1/22, as the graph below illustrates:

On the other hand, there are some interesting phenomena in Q1/22. Firstly, Japan’s proportion of adware activity has increased significantly in February and March; see the graph below. There is also an interesting correlation with Emotet hitting Japanese inboxes in the same period.

On the contrary, the situation in Ukraine led to a decrease in the adware activity in March; see the graph below showing the adware activity in Ukraine in Q1/22.

Finally, another interesting observation concerns adware activity in major European countries such as France, Germany, and the United Kingdom. The graph below shows increased activity in these countries in March, deviating from the trend of Q1/22.

Concerning the top strains, most of 64% of adware was from various adware families. However, the first clearly identified family is RelevantKnowledge, although so far with a low prevalence (5%) but with a +97% increase compared to Q4/21. Other identified strains in percentage units are ICLoader, Neoreklami, DownloadAssistant, and Conduit.

As mentioned above, the adware activity has a similar trend as in Q4/21. Therefore the risk ratios remained the same. The most affected regions are still Africa and Asia. About Q1/22 data, we monitored an increase of protected users in Japan (+209%) and France (+87%) compared with Q4/21. On the other hand, a decrease was observed in the Russian Federation (-51%) and Ukraine (-50%).

Adware risk ratio in Q1/22.

Martin Chlumecký, Malware Researcher

Bots

It seems that we are on a rollercoaster with Emotet and Trickbot. Last year, we went through Emotet takedown and its resurrection via Trickbot. This quarter, shutdowns of Trickbot’s infrastructure and Conti’s internal communication leaks indicate that Trickbot has finished its swan song. Its developers were supposedly moved to other Conti projects, possibly also with BazarLoader as Conti’s new product. Emotet also introduced a few changes – we’ve seen a much higher cadence of new, unique configurations. We’ve also seen a new configuration timestamp in the log “20220404”, interestingly seen on 24th March, instead of the one we’ve been accustomed to seeing (“20211114”).

There has been a new-ish trend coming with the advent of the war in Ukraine. Simple Javascript code has been used to create requests to (mostly) Russian web pages – ranging from media to businesses to banks. The code was accompanied by a text denouncing Russian aggression in Ukraine in multiple languages. The code has quickly spread around the internet into different variations, such as a variant of open-sourced game 2048. Unfortunately, we’ve started to see webpages that incorporated that code without even declaring it so it could even happen that your computer would participate in those actions while you were checking the weather on the internet. While these could remind us of Anonymous DDoS operations and LOIC (open-source stress tool Low Orbit Ion Cannon), these pages were much more accessible to the public using their browser only with (mostly) predetermined lists of targets. Nearing the end of March, we saw a significant decline in their popularity, both in terms of prevalence and the appearance of new variants.

The rest of the landscape does not bring many surprises. We’ve seen a significant risk increase in Russia (~30%) and Ukraine (~15%); those shouldn’t be much of a surprise, though, for the latter, it mostly does not project much into the number of affected clients.

In terms of numbers, the most prevalent strain was Emotet which doubled its market share since last quarter. Since the previous quarter, most of the other top strains slightly declined their prevalence. The most common strains we are seeing are:

• Emotet
• Amadey
• Phorpiex
• MyloBot
• Nitol
• MyKings
• Dorkbot
• Tofsee
• Qakbot

Adolf Středa, Malware Researcher

Coinminers

Coincidently, as the cryptocurrency prices are somewhat stable these days, the same goes for the malicious coinmining activity in our user base.

In comparison with the previous quarter, crypto-mining threat actors increased their focus on Taiwan (+69%), Chile (+63%), Thailand (+61%), Malawi (+58%), and France (+58%). This is mainly caused by the continuous and increasing trend of using various web miners executing javascript code in the victim’s browser. On the other hand, the risk of getting infected significantly dropped in Denmark (-56%) and Finland (-50%).

The most common coinminers in Q1/22 were:

• XMRig
• NeoScrypt
• CoinBitMiner
• CoinHelper

Jan Rubín, Malware Researcher

Information Stealers

The activities of Information Stealers haven’t significantly changed in Q1/22 compared to Q4/21. FormBook, AgentTesla, and RedLine remain the most prevalent stealers; in combination, they are accountable for 50% of the hits within the category. 

We noticed the regional distribution has completely shifted compared to the previous quarter. In Q4/21, Singapore, Yemen, Turkey, and Serbia were the countries most affected by information stealers; in Q1/22, Russia, Brazil, and Argentina rose to the top tier after the increases in risk ratio by 27% (RU), 21% (BR), and 23% (AR) compared to the previous quarter.

Not only a popular destination for information stealers, Latin America also houses many regional-specific stealers capable of compromising victims’ banking accounts. As the underground hacking culture continues to develop in Brazil, these threat groups target their fellow citizens for financial purposes. In Brazil, Ousaban and Chaes pose the most significant threats with more than 100k and 70k hits. In Mexico in Q1/22, we observed more than 34k hits from Casbaneiro. A typical pattern shared between these groups is the multiple-stage delivery chain utilizing scripting languages to download and deploy the next stage’s payload while employing DLL sideloading techniques to execute the final stage.

Furthermore, Raccoon Stealer, an information stealer with Russian origins, significantly decreased in activity since March. Further investigation uncovered messages on Russian underground forums advising that the Raccoon group is not working anymore. A few days after the messages were posted, a Raccoon representative said one of their members died in the Ukrainian War – they have paused operations and plan to return in a few months with a new product.

Next, a macOS malware dubbed DazzleSpy was found using watering hole attacks targeting Chinese pro-democracy sympathizers; it was primarily active in Asia. This backdoor can control macOS remotely, execute arbitrary commands, and download and upload files to attackers, thus enabling keychain stealing, key-logging, and potential screen capture.

Last but not least, more malware that natively runs on M1 Apple chips (and Intel hardware) has been found. The malware family, SysJoker, targets all desktop platforms (Linux, Windows, and macOS); the backdoor is controlled remotely and allows downloading other payloads and executing remote commands.

Anh Ho, Malware Researcher
Igor Morgenstern, Malware Researcher
Vladimir Martyanov, Malware Researcher
Vladimír Žalud, Malware Analyst

Ransomware

We’ve previously reported a decline in the total number of ransomware attacks in Q4/21. In Q1/22, this trend continued with a further slight decrease. As can be seen on the following graph, there was a drop at the beginning of 2022; the number of ransomware attacks has since stabilized.

We believe there are multiple reasons for these recent declines – such as the geopolitical situation (discussed shortly) and the continuation of the trend of ransomware gangs focusing more on targeted attacks on big targets (big game hunting) rather than on regular users via the spray and pray techniques. In other words, ransomware is still a significant threat, but the attackers have slightly changed their targets and tactics. As you will see in the rest of this section, the total numbers are lower, but there was a lot ongoing regarding ransomware in Q1.

Based on our telemetry, the distribution of targeted countries is similar to Q4/21 with some Q/Q shifts, such as Mexico (+120% risk ratio), Japan (+37%), and India (+34%).

The most (un)popular ransomware strains – STOP and WannaCry – kept their position at the top. Operators of the STOP ransomware keep releasing new variants, and the same applies for the CrySiS ransomware. In both cases, the ransomware code hasn’t considerably evolved, so a new variant merely means a new extension of encrypted files, different contact e-mail and a different public RSA key.

The most prevalent ransomware strains in Q1/22:

• WannaCry
• STOP
• VirLock
• GlobeImposter
• Makop

Out of the groups primarily focused on targeted attacks, the most active ones based on our telemetry were LockBit, Conti, and Hive. The BlackCat (aka ALPHV) ransomware was also on the rise. The LockBit group boosted their presence and also their egos, as demonstrated by their claim that they will pay any FBI agent that reveals their location a bounty of $1M. Later, they expanded that offer to any person on the planet.

You may also recall Sodinokibi (aka REvil), which is regularly mentioned in our threat reports. There is always something interesting around this ransomware strain and its operators with ties to Russia. In our Q4/21 Threat Report we informed about the arrests of some of its operators by Russian authorities. Indeed, this resulted in Sodinokibi almost vanishing from the threat landscape in Q1/2022. However, the situation got messy at the very end of Q1/2022 and early in April as new Sodinokibi indicators started appearing, including the publishing of new leaks from ransomed companies and malware samples. It is not yet clear whether this is a comeback, an imposter operation, reused Sodinokibi sources or infrastructure, or even their combination by multiple groups. Our gut feeling is that Sodinokibi will be a topic in the Q2/22 Threat Report once again.

Russian ransomware affiliates are a never-ending story. E.g. we can mention an interesting public exposure of a criminal dubbed Wazawaka with ties to Babuk, DarkSide, and other ransomware gangs in February. In a series of drunk videos and tweets he revealed much more than his missing finger.

The Russian invasion and following war on Ukraine, the most terrible event in Q1/22, had its counterpart in cyber-space. Just one day before the invasion, several cyber attacks were detected. Shortly after the discovery of HermeticWiper malware by ESET, Avast also discovered ransomware attacking Ukrainian targets. We dubbed it HermeticRansom. Shortly after, a flaw in the ransomware was found by CrowdStrike analysts. We acted swiftly and released a free decryptor to help victims in Ukraine. Furthermore, the war impacted ransomware attacks, as some of the ransomware authors and affiliates are from Ukraine and likely have been unable to carry out their operations due to the war.

And the cyber-war went on, together with the real one. A day after the start of the invasion, the Conti ransomware gang claimed its allegiance and threatened anyone who was considering organizing a cyber-attack or war activities against Russia:

As a reaction, a Ukrainian researcher started publishing internal files of the Conti gang, including Jabber conversations and the source code of the Conti ransomware itself. However, no significant amount of encryption keys were leaked. Also, the sources that were published were older versions of the Conti ransomware, which no longer correspond to the layout of the encrypted files that are created by today’s version of the ransomware. The leaked files and internal communications provide valuable insight into this large cybercrime organization, and also temporarily slowed down their operations.

Among the other consequences of the Conti leak, the published source codes were soon used by the NB65 hacking group. This gang declared a karmic war on Russia and used one of the modified sources of the Conti ransomware to attack Russian targets.

Furthermore, in February, members of historically one of the most active (and successful) ransomware groups, Maze, announced a shut-down of their operation. They published master decryption keys for their ransomware strains Maze, Egregor, and Sekhmet; four archive files were published that contained:

• 19 private RSA-2048 keys for Egregor ransomware. Egregor uses a three-key encryption schema (Master RSA Key → Victim RSA Key → Per-file Key).
• 30 private RSA-2048 keys (plus 9 from old version) for Maze ransomware. Maze also uses a three-key encryption scheme.
• A single private RSA-2048 key for Sekhmet ransomware. Because this strain uses this RSA key to encrypt the per-file key, the RSA private key is likely campaign specific.
• A source code for the M0yv x86/x64 file infector, that was used by Maze operators in the past.

Next, an unpleasant turn of events happened after we released a decryptor for the TargetCompany ransomware in February. This immediately helped multiple ransomware victims; however, two weeks later, we discovered a new variant of TargetComany that started using the ”.avast” extension for encrypted files. Shortly after, the malware authors changed the encryption algorithm, so our free decryption tool does not decrypt the most recent variant.

On the bright side, we also analyzed multiple variants of the Prometheus ransomware and released a free decryptor. This one covers all decryptable variants of the ransomware strain, even the latest ones.

Jakub Křoustek, Malware Research Director
Ladislav Zezula, Malware Researcher

Remote Access Trojans (RATs)

New year, new me RAT campaigns. As mentioned in the Q4/21 report, the RAT activity downward trend will be just temporary; the reality was a textbook example of this claim. Even malicious actors took holidays at the beginning of the new year and then returned to work.

In the graph below, we can see a Q4/21 vs. Q1/22 comparison of RAT activity:

This quarter’s countries most affected were China, Tajikistan, Kyrgyzstan, Iraq, Kazakhstan, and Russia. Kazakhstan will be mentioned later on with the emergence of a new RAT. We also detected a high Q/Q increase in the risk ratio in countries involved in the ongoing war: Ukraine (+54%), Russia (+53%), and Belarus (+46%).

In this quarter, we spotted a new campaign distributing several RATs, reaching thousands of users, mainly in Italy (1,900), Romania (1,100), and Bulgaria (950). The campaign leverages a Crypter (a crypter is a specific tool used by malware authors for obfuscation and protection of the target payload), which we call Rattler, that ensures a distribution of arbitrary malware onto the victim’s PC. Currently, the crypter primarily distributes remote access trojans, focusing on Warzone, Remcos, and NetWire. Warzone’s main targeting campaigns also seemed to change during the past three months. In January and February, we received a considerable amount of detections from Russia and Ukraine. Still, this trend reversed in March, with decreased detections in these two countries and a significant increase in Spain, indicating a new malicious campaign.

Most prevalent RATs in Q1 were:

• njRAT
• Warzone
• Remcos
• AsyncRat
• NanoCore
• NetWire
• QuasarRAT
• PoisionIvy
• Adwind
• Orcus

Among malicious families with the highest increase in detections were Lilith, LuminosityLink, and Gh0stCringe. One of the reasons for the Gh0stCringe increase is a malicious campaign in which this RAT spread on poorly protected MySQL and Microsoft SQL database servers. We have also witnessed a change in the first two places of the most prevalent RATs. In Q4/21, the most pervasive was Warzone which declined this quarter by 23%. The njRat family, on the other hand, increased by 32%, and what was surprising, Adwind entered into the top 10.

Except for the usual malicious campaigns, this quarter was different. There were two significant causes for this. The first was a Lapsus$ hacking and leaking spree, and the other was the war with Ukraine.

The hacking group Lapsus$ targeted many prominent technology companies like Nvidia, Samsung, and Microsoft. For example, in the NVIDIA Lapsus$ case, this hacking group stole about 1TB of NVIDIA’s data and then commenced to leak it. The leaked data contained binary signing certificates, which were later used for signing malicious binaries. Among such signed malware was, for example, the Quasar RAT.

Then there was the conflict in Ukraine, which showed the power of information technology and the importance of cyber security – because the fight happens not only on the battlefield but also in cyberspace, with DDOS attacks, data-stealing, exploitation, cyber espionage, and other techniques. But except for these countries involved in the war, everyday people looking for information are easy targets of malicious campaigns. One such campaign involved sending email messages with attached office documents that allegedly contained important information about the war. Unfortunately, these documents were just a way to infect people with Remcos RAT with the help of Microsoft Word RCE vulnerability CVE-2017-11882, thanks to which the attacker could easily infect unpatched systems.

As always, not only old known RATs showed up. This quarter brought us a few new ones as well. The first addition to our RAT list was IceBot. This RAT seems to be a creation of the APT group FIN7; it contains all usual basic capabilities as other RATs like taking screenshots, remote code execution, file transfer, and detection of installed AV.

Another one is Hodur. This RAT is a variant of PlugX (also known as Korplug), associated with Chinese APT organizations. Hodur differed, using a different encoding, configuration capabilities, and  C&C commands. This RAT allows attackers to log keystrokes, manipulate files, fingerprint the system and more.

We mentioned that Kazakhstan is connected to a new RAT on this list. That RAT is called Borat RAT. The name is taken from the popular comedy film Borat where the main character Borat Sagdijev, performed by actor Sacha Baron Cohen, was presented as a Kazakh visiting the USA. Did you know that in reality the part of the film that should represent living in Kazakhstan village wasn’t even filmed there but in the Romanian village of Glod?

This RAT is a .NET binary and uses simple source-code obfuscation. The Borat RAT was initially discovered on hacking forums and contains many capabilities. Some features include triggering BSOD, anti-sandbox, anti-VM, password stealing, web-cam spying, file manipulation and more. As well as these baked-in features, it enables extensive module functionality. These modules are DLLs that are downloaded on demand, allowing the attackers to add multiple new capabilities. The list of currently available modules contains files “Ransomware.dll” used for encrypting files, “Discord.dll” for stealing Discord tokens, and many more.

Here you can see an example of the Borat RAT admin panel. 

We also noticed that the volume of Python compiled and Go programming language ELF binaries for Linux increased this quarter. The threat actors used open source RAT projects (i.e. Bring Your Own Botnet or Ares) and legitimate services (e.g. Onion.pet, termbin.com or Discord) to compromise systems. We were also one of the first to protect users against Backdoorit and Caligula RATs; both of these malware families were written in Go and captured in the wild by our honeypots.

Samuel Sidor, Malware Researcher
Jan Rubín, Malware Researcher
David Àlvarez, Malware Researcher

Rootkits

In Q1/22,  rootkit activity was reduced compared to the previous quarter, returning to the long-term value, as illustrated in the chart below.

The close-up view of Q1/22 demonstrates that January and February have been more active than the March period.

We have monitored various rootkit strains in Q1/22. However, we have identified that approx. 37% of rootkit activity is r77-Rootkit (R77RK) developed by bytecode77 as an open-source project under the BSD license. The rootkit operates in Ring 3 compared to the usual rootkits that work in Ring 0. R77RK is a configurable tool hiding files, directories, scheduled tasks, processes, services, connections, etc. The tool is compatible with Windows 7 and Windows 10. The consequence is that R77RK was captured with several different types of malware as a supporting library for malware that needs to hide malicious activity.

The graph below shows that China is still the most at-risk country in terms of protected users. Moreover, the risk in China has increased by about +58%, although total rootkit activity has been orders of magnitude lower compared to Q4/21. This phenomenon is caused by the absence of the Cerbu rootkit that was spread worldwide, so the main rootkit activity has moved back to China. Namely, the decrease in the rootkit activity has been observed in the countries as follows: Vietnam, Thailand, the Czech Republic, and Egypt.

In summary, the situation around the rootkit activity seems calmer compared to Q4/21, and China is still the most affected country in Q1/22. Noteworthy, the war in Ukraine has not increased the rootkit activity. Numerous malware authors have started using open-source solutions of rootkits, although these are very well detectable.

Martin Chlumecký, Malware Researcher

Technical support scams

After quite an active Q4/21 that overlapped with the beginning of Q1/22, technical support scams started to decline in inactivity. There were some small peaks of activity, but the significant wave of one particular campaign came at the end of Q1/22.

According to our data, the most targeted countries were the United States and Canada. However, we’ve seen instances of this campaign active even in other areas, like Europe, for example, France and Germany.

The distinctive sign of this campaign was the lack of a domain name and a specific path; this is illustrated in the following image.

During the beginning of March, we collected thousands of new unique domain-less URLs that have one significant and distinctive sign, their url path. After being redirected, an affected user loads a web page with a well-known recycled appearance, used in many previous technical support campaigns. In addition, several pop-up windows, the logo of well-known companies, antivirus-like messaging, cursor manipulation techniques, and even sounds are all there for one simple reason: a phone call to the phone number shown.

More than twenty different phone numbers have been used. Examples of such numbers can be seen in the following table:

1-888-828-5604
1-888-200-5532
1-877-203-5120
1-888-770-6555
1-855-433-4454
1-833-576-2199
1-877-203-9046
1-888-201-5037
1-866-400-0067
1-888-203-4992

Alexej Savčin, Malware Analyst

Traffic Direction System (TDS)

A new Traffic Direction System (TDS) we are calling Parrot TDS was very active throughout Q1/2022. The TDS has infected various web servers hosting more than 16,500 websites, ranging from adult content sites, personal websites, university sites, and local government sites.

Parrot TDS acts as a gateway for other malicious campaigns to reach potential victims. In this particular case, the infected sites’ appearances are altered by a campaign called FakeUpdate (also known as SocGholish), which uses JavaScript to display fake notices for users to update their browser, offering an update file for download. The file observed being delivered to victims is a remote access tool.

From March 1, 2022, to March 29, 2022, we protected more than 600,000 unique users from around the globe from visiting these infected sites. We protected the most in Brazil – over  73,000 individual users, in India – nearly 55,000 unique users, and more than 31,000 unique users from the US.

Jan Rubín, Malware Researcher
Pavel Novák, Threat Operations Analyst

Vulnerabilities and Exploits

Spring in Europe has had quite a few surprises for us, one of them being a vulnerability in a Java framework called, ironically, Spring. The vulnerability is called Spring4Shell (CVE-2022-22963), mimicking the name of last year’s Log4Shell vulnerability. Similarly to Log4Shell, Spring4Shell leads to remote code execution (RCE). Under specific conditions, it is possible to bind HTTP request parameters to Java objects. While there is a logic protecting classLoader from being used, it was not foolproof, which led to this vulnerability. Fortunately, the vulnerability requires a non-default configuration, and a patch is already available.

The Linux kernel had its share of vulnerabilities; a vulnerability was found in pipes, which usually provide unidirectional interprocess communication, that can be exploited for local privilege escalation. The vulnerability was dubbed Dirty Pipe (CVE-2022-0847). It relies on the usage of partially uninitialized memory of the pipe buffer during its construction, leading to an incorrect value of flags, potentially providing write-access to pages in the cache that were originally marked with a read-only attribute. The vulnerability is already patched in the latest kernel versions and has already been fixed in most mainstream Linux distributions.

First described by Trend Micro researchers in 2019, the SLUB malware is a highly targeted and sophisticated backdoor/RAT spread via browser exploits. Now, three years later, we detected its new exploitation attack, which took place in Japan and targeted an outdated Internet Explorer.

The initial exploit injects into winlogon.exe, which will, in turn, download and execute the final stage payload. The final stage did not change much since the initial report, and it still uses Slack as a C&C server but now uses file[.]io for data exfiltration.

This is an excellent example that old threats never really go away; they often continue to evolve and pose a threat.

Adolf Středa, Malware Researcher
Jan Vojtěšek, Malware Reseracher

Mikrotik CVEs keep giving

It’s been almost four years since the very severe vulnerability CVE-2018-14847 targeting MikroTik devices first appeared. What seemed to be yet another directory traversal bug quickly escalated into user database and password leaks, resulting in a potentially disastrous vulnerability ready to be misused by cybercriminals. Unfortunately, the simplicity of exploiting and wide adoption of these devices and powerful features provided a solid foundation for various malicious campaigns being executed using these devices. It first started with injecting crypto mining javascript into pages script by capturing the traffic, poisoning the DNS cache, and incorporating these devices into botnets for DDoS and proxy purposes.  

Unfortunately, these campaigns come in waves, and we still observe MikroTik devices being misused repeatedly. In Q1/22, we’ve seen a lot of exciting twists and turns, the most prominent of which was probably the Conti group leaks which also shed light on the TrickBot botnet. For quite some time, we knew that TrickBot abused MikroTik devices as proxy servers to hide the next tier of their C&C. The leaking of Conti and Trickbot infrastructure meant the end of this botnet. However, it also provided us clues and information about one of the vastest botnets as a service operation connecting Glupteba, Meris, crypto mining campaigns, and, perhaps also, TrickBot. We are talking about 230K devices controlled by one threat actor and rented out as a service. You can find more in our research Mēris and TrickBot standing on the shoulders of giants. 

A few days before we published our research in March, a new story emerged describing the DDoS campaign most likely tied to the Sodinokibi ransomware group. Unsurprisingly most of the attacking devices were MikroTik again. A few days ago, we were contacted by security researchers from SecurityScoreCard. They have observed another DDoS botnet called Zhadnost targeting Ukrainian institutions and again using MikroTik devices as an amplification vector. This time, they were mainly misusing DNS amplification vulnerabilities. 

We also saw one compelling instance of a network security incident potentially involving MikroTik routers. In the infamous cyberattack on February 24th against the Viasat KA-SAT service, attackers penetrated the management segment of the network and wiped firmware from client terminal devices.

The incident surfaced more prominently after the cyberattack paralyzed 11 gigawatts of German wind turbine production as a probable spill-over from the KA-SAT issue. The connectivity for turbines is provided by EuroSkyPark, one of the satellite internet providers using the KA-SAT network.

When we analyzed ASN AS208484, an autonomous system assigned to EuroSkyPark, we found 15 MikroTik devices with exposed TCP port 8728, which is used for API access to administer the devices. Also of concern, one of the devices had a port for an infamously vulnerable WinBox protocol port exposed to the Internet. As of now, all mentioned ports are closed and no longer accessible.

We also found SSH access remapped to non-standard ports such as 9992 or 9993. This is not typically common practice and may also indicate compromise. Attackers have been known to remap the ports of standard services (such as SSH) to make it harder to detect or even for the device owner to manage. However, this could also be configured deliberately for the same reason: to hide SSH access from plain sight.

From all the above, it’s apparent that we can expect to see similar patterns and DDoS attacks carried not only by MikroTik devices but also by other vulnerable IoT devices in the foreseeable future. On a positive note, the number of MikroTik devices vulnerable to the most commonly misused CVEs is slowly decreasing as new versions of RouterOS (OS that powers the MikroTik appliances) are rolled out. Unfortunately, however, there are many devices already compromised, and without administrative intervention, they will continue to be used for malicious operations repeatedly. 

We strongly recommend that MikroTik administrators ensure they have updated and patched to protect themselves and others.  

If you are a researcher and you think you have seen MikroTik devices involved in some malicious activity, please consider contacting us if you need help or consultation; since 2018, we have built up a detailed understanding of these devices’ threat landscape.

Martin Hron, Malware Researcher

Web skimming

In Q1/22, the most prevalent web skimming malicious domain was naturalfreshmall[.]com, with more than 500 e-commerce sites infected. The domain itself is no longer active, but many websites are still trying to retrieve malicious content from it. Unfortunately, it means that administrators of these sites still have not removed malicious code and these sites are likely still vulnerable. Avast protected 44k users from this attack in the first quarter.

The heatmap below shows the most affected countries in Q1/22 – Saudi Arabia, Australia, Greece, and Brazil. Compared to Q4/21, Saudi Arabia, Australia and Greece stayed at the top, but in Brazil, we protected almost two times more users than in the previous quarter. However, multiple websites were infected in Brazil, some with the aforementioned domain naturalfreshmall[.]com. In addition, we tweeted about philco.com[.]br, which was infected with yoursafepayments[.]com/fonts.css. And last but not least, pernambucanas.com[.]br was also infected with malicious javascript hidden in the file require.js on their website.

Overall the number of protected users remains almost the same as in Q4/21.

Pavlína Kopecká, Malware Analyst

Mobile-Related Threats

Adware/HiddenAds

Adware maintains its dominance over the Android threat landscape, continuing the trend from previous years. Generally, the purpose of Adware is to display out-of-context advertisements to the device user, often in ways that severely impact the user experience. In Q1/22, HiddenAds, FakeAdblockers, and others have spread to many Android devices; these applications often display device-wide advertisements that overlay the user’s intended activity or limit the app’s functionality by displaying timed ads without the ability to skip them.

Adware comes in various configurations; one popular category is stealthy installation. Such apps share common features that make them difficult for the user to identify. Hiding their application's icon from the home screen is a common technique, and using blank application icons to mask their presence. The user may struggle to identify the source of the intrusive advertisements, especially if the applications have an in-built delay timer after which they display the ads. Another Adware tactic is to use in-app advertisements that are overly aggressive, sometimes to the extent that they make the original app’s intended functionality barely usable. This is common, especially in games, where timed ads are often shown after each completed level; frequently, the ad screen time greatly exceeds the time spent playing the game.

The Google Play Store has previously been used to distribute malware, but recently, actors behind these applications have changed tactics to use browser pop-up windows and notifications to spread the Adware. These are intended to trick users into downloading and installing the application, often disguised as games, ad blockers, or various utility tools. Therefore, we strongly recommend that users avoid installing applications from unknown sources and be on the lookout for malicious browser notifications.

According to our data, India, the Middle East, and South America are the most affected regions. But Adware is not strictly limited to these regions; it’s prevalent worldwide.

As can be seen from the graph below, Adware’s presence in the mobile sphere has remained dominant but relatively unchanged. Of course, there’s slight fluctuation during each quarter, but there have been no stand-out new strains of Adware as of late.

Bankers

In Q1/2022, some interesting shifts were observed in the banking malware category. With Cerberus/Alien and its clones still leading the scoreboard by far, the battle for second place has seen a jump, where Hydra replaced the previously significant threats posed by FluBot. Additionally, FluBot has been on the decline throughout Q1..

Different banker strains have been reported to use the same distribution channels and branding, which we can also confirm observing. Many banking threats now reuse the proven techniques of masquerading as delivery services, parcel tracking apps, or voicemail apps.

After the departure of FluBot from the scene, we observed an overall slight drop in the number of affected users, but this seems only to be returning to the numbers we’ve observed in the last year, just before FluBot took the stage.

Most targeted countries remain to be Turkey, Spain and Australia.

PremiumSMS/Subscription scams

While PremiumSMS/Subscription related threats may not be as prevalent as in the previous years, they are certainly not gone for good. As reported in the Q4/21 report, a new wave of premium subscription-related scams keeps popping up. Campaigns such as GriftHorse or UltimaSMS made their rounds last year, followed by yet another similar campaign dubbed DarkHerring. 

The main distribution channel for these seems to be Google Play, but they have also been observed being downloaded from alternative channels. Similar to before, this scam preys on the mobile operator’s subscription scheme, where an unsuspecting user is lured into giving out their phone number. The number is later used to register the victim to a premium subscription service. This can go undetected for a long time, causing the victim significant monetary loss due to the stealthiness of the subscription and hassle related to canceling such a subscription.

While the primary target of these campaigns seems to remain the same as in Q4/21 – targeting the Middle East, countries like Iraq, Jordan, but also Saudi Arabia, and Egypt – the scope has broadened and now includes various Asian countries as well – China, Malaysia and Vietnam amongst the riskiest ones.

As can be seen from the quarterly comparisons in the graph below, the spikes of activity of the respective campaigns are clear, with UltimaSMS and Grifthorse causing the spike in Q4/21. Darkherring is behind the Q1/22 spike.

Ransomware/Lockers

Ransomware apps and Lockers that target the Android ecosystem often attempt to ‘lock’ the user’s phone by disabling the navigation buttons and taking over the Android lock screen to prevent the user from interacting with the device and removing the malware. This is commonly accompanied by a ransom message requesting payment to the malware owner in exchange for unlocking the device.

Among the most prevalent Android Lockers seen in Q1/22 were Jisut, Pornlocker, and Congur. These are notorious for being difficult to remove and, in some cases, may require a factory reset of the phone. Some versions of lockers may even attempt to encrypt the user’s files; however, this is not frequently seen due to the complexity of encrypting files on Android devices.

The threat actors responsible for this malware generally rely on spreading through the use of third party app stores, game cheats, and adult content applications.

A common infection technique is to lure users through popular internet themes and topics – we strongly recommend that users avoid attempting to download game hacks and mods and ensure that they use reputable websites and official app stores.

In Q1/22, we’ve seen spikes in this category, mainly related to the Pornlocker family – apps masquerading as adult content providers – and were predominantly targeting users in Russia.

In the graph above, we can see the spike caused by the Pornlocker family in Q1/22.

Ondřej David, Malware Analysis Team Lead
Jakub Vávra, Malware Analyst

Acknowledgements / Credits

The post Avast Q1/2022 Threat Report appeared first on Avast Threat Labs.

Avast Releases Decryptor for the Prometheus Ransomware. Prometheus is a ransomware strain written in C# that inherited a lot of code from an older strain called Thanos.

Skip to how to use the Prometheus ransomware decryptor. 

How Prometheus Works

Prometheus tries to thwart malware analysis by killing various processes like packet sniffing, debugging or tools for inspecting PE files. Then, it generates a random password that is used during the Salsa20 encryption. 

Prometheus looks for available local drives to encrypt files that have one of the following  extensions:

db dbf accdb dbx mdb mdf epf ndf ldf 1cd sdf nsf fp7 cat log dat txt jpeg gif jpg png php cs cpp rar zip html htm xlsx xls avi mp4 ppt doc docx sxi sxw odt hwp tar bz2 mkv eml msg ost pst edb sql odb myd php java cpp pas asm key pfx pem p12 csr gpg aes vsd odg raw nef svg psd vmx vmdk vdi lay6 sqlite3 sqlitedb java class mpeg djvu tiff backup pdf cert docm xlsm dwg bak qbw nd tlg lgb pptx mov xdw ods wav mp3 aiff flac m4a csv sql ora dtsx rdl dim mrimg qbb rtf 7z 

Encrypted files are given a new extension .[ID-<PC-ID>].unlock. After the encryption process is completed, Notepad is executed with a ransom note from the file UNLOCK_FILES_INFO.txt informing victims on how to pay the ransom if they want to decrypt their files.

How to use the Avast decryptor to decrypt files encrypted by Prometheus Ransomware

To decrypt your files, follow these steps:

1. Download the free Avast decryptor.
2. Run the executable file. It starts in the form of a wizard, which leads you through the configuration of the decryption process.
3. On the initial page, you can read the license information, if you want, but you really only need to click “Next”.

4. On the next page, select the list of locations you want to be searched and decrypted. By default, it contains a list of all local drives:

5. On the third page, you need to provide a file in its original form and encrypted by the Prometheus ransomware. Enter both names of the files. In case you have an encryption password created by a previous run of the decryptor, you can select the “I know the password for decrypting files” option:

6. The next page is where the password cracking process takes place. Click “Start” when you are ready to start the process. During the password cracking process, all your available processor cores will spend most of their computing power to find the decryption password. The cracking process may take a large amount of time, up to tens of hours. The decryptor periodically saves the progress and if you interrupt it and restart the decryptor later, it offers you the option to resume the previously started cracking process. Password cracking is only needed once per PC – no need to do it again for each file.

7. When the password is found, you can proceed to decrypt all encrypted files on your PC by clicking “Next”.

8. On the final page, you can opt-in to backup encrypted files. These backups may help if anything goes wrong during the decryption process. This option is turned on by default, which we recommend. After clicking “Decrypt”, the decryption process begins. Let the decryptor work and wait until it finishes decrypting all of your files.

IOCs

SHA256	File Extension
742bc4e78c36518f1516ece60b948774990635d91d314178a7eae79d2bfc23b0	.[ID-<HARDWARE_ID>].unlock

The post Decrypted: Prometheus Ransomware appeared first on Avast Threat Labs.

On February 24th, the Avast Threat Labs discovered a new ransomware strain accompanying the data wiper HermeticWiper malware,  which our colleagues at ESET found circulating in the Ukraine. Following this naming convention, we opted to name the strain we found piggybacking on the wiper, HermeticRansom. According to analysis done by Crowdstrike’s Intelligence Team, the ransomware contains a weakness in the crypto schema and can be decrypted for free.

If your device has been infected with HermeticRansom and you’d like to decrypt your files, click here to skip to the How to use the Avast decryptor to recover files

Go!

The ransomware is written in GO language. When executed, it searches local drives and network shares for potentially valuable files, looking for  files with one of the extensions listed below (the order is taken from the sample):

.docx .doc .dot .odt .pdf .xls .xlsx .rtf .ppt .pptx .one.xps .pub .vsd .txt .jpg .jpeg .bmp .ico .png .gif .sql.xml .pgsql .zip .rar .exe .msi .vdi .ova .avi .dip .epub.iso .sfx .inc .contact .url .mp3 .wmv .wma .wtv .avi .acl.cfg .chm .crt .css .dat .dll .cab .htm .html .encryptedjb

In order to keep the victim’s PC operational, the ransomware avoids encrypting files in Program Files and Windows folders.

For every file designated for encryption, the ransomware creates a 32-byte encryption key. Files are encrypted by blocks, each block has 1048576 (0x100000) bytes. A maximum of nine blocks are encrypted. Any data past 9437184 bytes (0x900000) is left in plain text. Each block is encrypted by AES GCM symmetric cipher. After data encryption, the ransomware appends a file tail, containing the RSA-2048 encrypted file key. The public key is stored in the binary as a Base64 encoded string:

Encrypted file names are given extra suffix:

.[[email protected]].encryptedJB

When done, a file named “read_me.html” is saved to the user’s Desktop folder:

There is an interesting amount of politically oriented strings in the ransomware binary. In addition to the file extension, referring to the re-election of Joe Biden in 2024, there is also a reference to him in the project name:

During the execution, the ransomware creates a large amount of child processes, that do the actual encryption:

How to use the Avast decryptor to recover files

To decrypt your files, please, follow these steps:

1. Download the free Avast decryptor.
2. Simply run the executable file. It starts in the form of a wizard, which leads you through the configuration of the decryption process.
3. On the initial page, you can read the license information, if you want, but you really only need to click “Next“

4. On the next page, select the list of locations which you want to be searched and decrypted. By default, it contains a list of all local drives:

5. On the final wizard page, you can opt-in whether you want to backup encrypted files. These backups may help if anything goes wrong during the decryption process. This option is turned on by default, which we recommend. After clicking “Decrypt”, the decryption process begins. Let the decryptor work and wait until it finishes.

IOCs

SHA256: 4dc13bb83a16d4ff9865a51b3e4d24112327c526c1392e14d56f20d6f4eaf382

The post Help for Ukraine: Free decryptor for HermeticRansom ransomware appeared first on Avast Threat Labs.

On January 25, 2022, a victim of a ransomware attack reached out to us for help. The extension of the encrypted files and the ransom note indicated the TargetCompany ransomware (not related to Target the store), which can be decrypted under certain circumstances.

Modus Operandi of the TargetCompany Ransomware

When executed, the ransomware does some actions to ease its own malicious work:

1. Assigns the SeTakeOwnershipPrivilege and SeDebugPrivilege for its process
2. Deletes special file execution options for tools like vssadmin.exe, wmic.exe, wbadmin.exe, bcdedit.exe, powershell.exe, diskshadow.exe, net.exe and taskkil.exe
3. Removes shadow copies on all drives using this command:
   %windir%\sysnative\vssadmin.exe delete shadows /all /quiet
4. Reconfigures boot options:
   bcdedit /set {current} bootstatuspolicy ignoreallfailures
bcdedit /set {current} recoveryenabled no
5. Kills some processes that may hold open valuable files, such as databases:

List of processes killed by the TargetCompany ransomware
MsDtsSrvr.exe	ntdbsmgr.exe
ReportingServecesService.exe	oracle.exe
fdhost.exe	sqlserv.exe
fdlauncher.exe	sqlservr.exe
msmdsrv.exe	sqlwrite
mysql.exe

After these preparations, the ransomware gets the mask of all logical drives in the system using the  GetLogicalDrives() Win32 API. Each drive is checked for the drive type by GetDriveType(). If that drive is valid (fixed, removable or network), the encryption of the drive proceeds. First, every drive is populated with the ransom note file (named RECOVERY INFORMATION.txt). When this task is complete, the actual encryption begins.

Exceptions

To keep the infected PC working, TargetCompany avoids encrypting certain folders and file types:

List of folders avoided by the TargetCompany ransomware
msocache	boot	Microsoft Security Client	Microsoft MPI
$windows.~ws	$windows.~bt	Internet Explorer	Windows Kits
system volume information	mozilla	Reference	Microsoft.NET
intel	boot	Assemblies	Windows Mail
appdata	windows.old	Windows Defender	Microsoft Security Client
perflogs	Windows	Microsoft ASP.NET	Package Store
programdata google application data	WindowsPowerShell	Core Runtime	Microsoft Analysis Services
tor browser	Windows NT	Package	Windows Portable Devices
	Windows	Store	Windows Photo Viewer
	Common Files	Microsoft Help Viewer	Windows Sidebar

List of file types avoided by the TargetCompany ransomware
.386	.cpl	.exe	.key	.msstyles	.rtp
.adv	.cur	.hlp	.lnk	.msu	.scr
.ani	.deskthemepack	.hta	.lock	.nls	.shs
.bat	.diagcfg	.icl	.mod	.nomedia	.spl
.cab	.diagpkg	.icns	.mpa	.ocx	.sys
.cmd	.diangcab	.ico	.msc	.prf	.theme
.com	.dll	.ics	.msi	.ps1	.themepack
	.drv	.idx	.msp	.rom	.wpx

The ransomware generates an encryption key for each file (0x28 bytes). This key splits into Chacha20 encryption key (0x20 bytes) and n-once (0x08) bytes. After the file is encrypted, the key is protected by a combination of Curve25519 elliptic curve + AES-128 and appended to the end of the file. The scheme below illustrates the file encryption. Red-marked parts show the values that are saved into the file tail after the file data is encrypted:

The exact structure of the file tail, appended to the end of each encrypted file, is shown as a C-style structure:

Every folder with an encrypted file contains the ransom note file. A copy of the ransom note is also saved into c:\HOW TO RECOVER !!.TXT

The personal ID, mentioned in the file, is the first six bytes of the personal_id, stored in each encrypted file.

How to use the Avast decryptor to recover files

To decrypt your files, please, follow these steps:

1. Download the free Avast decryptor. Choose a build that corresponds with your Windows installation. The 64-bit version is significantly faster and most of today’s Windows installations are 64-bit.
   • If you have 64-bit Windows, choose the 64-bit build.
   • If you have 32-bit Windows, choose the 32-bit build.
2. Simply run the executable file. It starts in the form of a wizard, which leads you through the configuration of the decryption process.
3. On the initial page, you can read the license information, if you want, but you really only need to click “Next”

4. On the next page, select the list of locations which you want to be searched and decrypted. By default, it contains a list of all local drives:
   

5. On the third page, you need to enter the name of a file encrypted by the TargetCompany ransomware. In case you have an encryption password created by a previous run of the decryptor, you can select the “I know the password for decrypting files” option:

6. The next page is where the password cracking process takes place. Click “Start” when you are ready to start the process. During password cracking, all your available processor cores will spend most of their computing power to find the decryption password. The cracking process may take a large amount of time, up to tens of hours. The decryptor periodically saves the progress and if you interrupt it and restart the decryptor later, it offers you an option to resume the previously started cracking process. Password cracking is only needed once per PC – no need to do it again for each file.

7. When the password is found, you can proceed to the decryption of files on your PC by clicking “Next”.

8. On the final wizard page, you can opt-in whether you want to backup encrypted files. These backups may help if anything goes wrong during the decryption process. This option is turned on by default, which we recommend. After clicking “Decrypt”, the decryption process begins. Let the decryptor work and wait until it finishes.

IOCs

SHA256	File Extension
98a0fe90ef04c3a7503f2b700415a50e62395853bd1bab9e75fbe75999c0769e	.mallox
3f843cbffeba010445dae2b171caaa99c6b56360de5407da71210d007fe26673	.exploit
af723e236d982ceb9ca63521b80d3bee487319655c30285a078e8b529431c46e	.architek
e351d4a21e6f455c6fca41ed4c410c045b136fa47d40d4f2669416ee2574124b	.brg

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