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Before yesterdayKrebs on Security

The Internet is Held Together With Spit & Baling Wire

26 November 2021 at 19:03

A visualization of the Internet made using network routing data. Image: Barrett Lyon, opte.org.

Imagine being able to disconnect or redirect Internet traffic destined for some of the world’s biggest companies — just by spoofing an email. This is the nature of a threat vector recently removed by a Fortune 500 firm that operates one of the largest Internet backbones.

Based in Monroe, La., Lumen Technologies Inc. [NYSE: LUMN] (formerly CenturyLink) is one of more than two dozen entities that operate what’s known as an Internet Routing Registry (IRR). These IRRs maintain routing databases used by network operators to register their assigned network resources — i.e., the Internet addresses that have been allocated to their organization.

The data maintained by the IRRs help keep track of which organizations have the right to access what Internet address space in the global routing system. Collectively, the information voluntarily submitted to the IRRs forms a distributed database of Internet routing instructions that helps connect a vast array of individual networks.

There are about 70,000 distinct networks on the Internet today, ranging from huge broadband providers like AT&T, Comcast and Verizon to many thousands of enterprises that connect to the edge of the Internet for access. Each of these so-called “Autonomous Systems” (ASes) make their own decisions about how and with whom they will connect to the larger Internet.

Regardless of how they get online, each AS uses the same language to specify which Internet IP address ranges they control: It’s called the Border Gateway Protocol, or BGP. Using BGP, an AS tells its directly connected neighbor AS(es) the addresses that it can reach. That neighbor in turn passes the information on to its neighbors, and so on, until the information has propagated everywhere [1].

A key function of the BGP data maintained by IRRs is preventing rogue network operators from claiming another network’s addresses and hijacking their traffic. In essence, an organization can use IRRs to declare to the rest of the Internet, “These specific Internet address ranges are ours, should only originate from our network, and you should ignore any other networks trying to lay claim to these address ranges.”

In the early days of the Internet, when organizations wanted to update their records with an IRR, the changes usually involved some amount of human interaction — often someone manually editing the new coordinates into an Internet backbone router. But over the years the various IRRs made it easier to automate this process via email.

For a long time, any changes to an organization’s routing information with an IRR could be processed via email as long as one of the following authentication methods was successfully used:

-CRYPT-PW: A password is added to the text of an email to the IRR containing the record they wish to add, change or delete (the IRR then compares that password to a hash of the password);

-PGPKEY: The requestor signs the email containing the update with an encryption key the IRR recognizes;

-MAIL-FROM: The requestor sends the record changes in an email to the IRR, and the authentication is based solely on the “From:” header of the email.

Of these, MAIL-FROM has long been considered insecure, for the simple reason that it’s not difficult to spoof the return address of an email. And virtually all IRRs have disallowed its use since at least 2012, said Adam Korab, a network engineer and security researcher based in Houston.

All except Level 3 Communications, a major Internet backbone provider acquired by Lumen/CenturyLink.

“LEVEL 3 is the last IRR operator which allows the use of this method, although they have discouraged its use since at least 2012,” Korab told KrebsOnSecurity. “Other IRR operators have fully deprecated MAIL-FROM.”

Importantly, the name and email address of each Autonomous System’s official contact for making updates with the IRRs is public information.

Korab filed a vulnerability report with Lumen demonstrating how a simple spoofed email could be used to disrupt Internet service for banks, telecommunications firms and even government entities.

“If such an attack were successful, it would result in customer IP address blocks being filtered and dropped, making them unreachable from some or all of the global Internet,” Korab said, noting that he found more than 2,000 Lumen customers were potentially affected. “This would effectively cut off Internet access for the impacted IP address blocks.”

The recent outage that took Facebook, Instagram and WhatsApp offline for the better part of a day was caused by an erroneous BGP update submitted by Facebook. That update took away the map telling the world’s computers how to find its various online properties.

Now consider the mayhem that would ensue if someone spoofed IRR updates to remove or alter routing entries for multiple e-commerce providers, banks and telecommunications companies at the same time.

“Depending on the scope of an attack, this could impact individual customers, geographic market areas, or potentially the [Lumen] backbone,” Korab continued. “This attack is trivial to exploit, and has a difficult recovery. Our conjecture is that any impacted Lumen or customer IP address blocks would be offline for 24-48 hours. In the worst-case scenario, this could extend much longer.”

Lumen told KrebsOnSecurity that it continued offering MAIL-FROM: authentication because many of its customers still relied on it due to legacy systems. Nevertheless, after receiving Korab’s report the company decided the wisest course of action was to disable MAIL-FROM: authentication altogether.

“We recently received notice of a known insecure configuration with our Route Registry,” reads a statement Lumen shared with KrebsOnSecurity. “We already had mitigating controls in place and to date we have not identified any additional issues. As part of our normal cybersecurity protocol, we carefully considered this notice and took steps to further mitigate any potential risks the vulnerability may have created for our customers or systems.”

Level3, now part of Lumen, has long urged customers to avoid using “Mail From” for authentication, but until very recently they still allowed it.

KC Claffy is the founder and director of the Center for Applied Internet Data Analysis (CAIDA), and a resident research scientist of the San Diego Supercomputer Center at the University of California, San Diego. Claffy said there is scant public evidence of a threat actor using the weakness now fixed by Lumen to hijack Internet routes.

“People often don’t notice, and a malicious actor certainly works to achieve this,” Claffy said in an email to KrebsOnSecurity. “But also, if a victim does notice, they generally aren’t going to release details that they’ve been hijacked. This is why we need mandatory reporting of such breaches, as Dan Geer has been saying for years.”

But there are plenty of examples of cybercriminals hijacking IP address blocks after a domain name associated with an email address in an IRR record has expired. In those cases, the thieves simply register the expired domain and then send email from it to an IRR specifying any route changes.

While it’s nice that Lumen is no longer the weakest link in the IRR chain, the remaining authentication mechanisms aren’t great. Claffy said after years of debate over approaches to improving routing security, the operator community deployed an alternative known as the Resource Public Key Infrastructure (RPKI).

“The RPKI includes cryptographic attestation of records, including expiration dates, with each Regional Internet Registry (RIR) operating as a ‘root’ of trust,” wrote Claffy and two other UC San Diego researchers in a paper that is still undergoing peer review. “Similar to the IRR, operators can use the RPKI to discard routing messages that do not pass origin validation checks.”

However, the additional integrity RPKI brings also comes with a fair amount of added complexity and cost, the researchers found.

“Operational and legal implications of potential malfunctions have limited registration in and use of the RPKI,” the study observed (link added). “In response, some networks have redoubled their efforts to improve the accuracy of IRR registration data. These two technologies are now operating in parallel, along with the option of doing nothing at all to validate routes.”

[1]: I borrowed some descriptive text in the 5th and 6th paragraphs from a CAIDA/UCSD draft paper — IRR Hygiene in the RPKI Era (PDF).

Further reading:

Trust Zones: A Path to a More Secure Internet Infrastructure (PDF).

Reviewing a historical Internet vulnerability: Why isn’t BGP more secure and what can we do about it? (PDF)

Arrest in ‘Ransom Your Employer’ Email Scheme

22 November 2021 at 21:57

In August, KrebsOnSecurity warned that scammers were contacting people and asking them to unleash ransomware inside their employer’s network, in exchange for a percentage of any ransom amount paid by the victim company. This week, authorities in Nigeria arrested a suspect in connection with the scheme — a young man who said he was trying to save up money to help fund a new social network.

Image: Abnormal Security.

The brazen approach targeting disgruntled employees was first spotted by threat intelligence firm Abnormal Security, which described what happened after they adopted a fake persona and responded to the proposal in the screenshot above.

“According to this actor, he had originally intended to send his targets—all senior-level executives—phishing emails to compromise their accounts, but after that was unsuccessful, he pivoted to this ransomware pretext,” Abnormal’s Crane Hassold wrote.

Abnormal Security documented how it tied the email back to a Nigerian man who acknowledged he was trying to save up money to help fund a new social network he is building called Sociogram. In June 2021, the Nigerian government officially placed an indefinite ban on Twitter, restricting it from operating in Nigeria after the social media platform deleted tweets by the Nigerian president.

Reached via LinkedIn, Sociogram founder Oluwaseun Medayedupin asked to have his startup’s name removed from the story, although he did not respond to questions about whether there were any inaccuracies in Hassold’s report.

“Please don’t harm Sociogram’s reputation,” Medayedupin pleaded. “I beg you as a promising young man.”

After he deleted his LinkedIn profile, I received the following message through the “contact this domain holder” link at KrebsOnSecurity’s domain registrar [curiously, the date of that missive reads “Dec. 31, 1969.”]. Apparently, Mr. Krebson is a clout-chasing monger.

A love letter from the founder of the ill-fated Sociogram.

Mr. Krebson also heard from an investigator representing the Nigeria Finance CERT on behalf of the Central Bank Of Nigeria. While the Sociogram founder’s approach might seem amateurish to some, the financial community in Nigeria did not consider it a laughing matter.

On Friday, Nigerian police arrested Medayedupin. The investigator says formal charges will be levied against the defendant sometime this week.

KrebsOnSecurity spoke with a fraud investigator who is performing the forensic analysis of the devices seized from Medayedupin’s home. The investigator spoke on condition of anonymity out of concern for his physical safety.

The investigator — we’ll call him “George” — said the 23-year-old Medayedupin lives with his extended family in an extremely impoverished home, and that the young man told investigators he’d just graduated from college but turned to cybercrime at first with ambitions of merely scamming the scammers.

George’s team confirmed that Medayedupin had around USD $2,000 to his name, which he’d recently stolen from a group of Nigerian fraudsters who were scamming people for gift cards. Apparently, he admitted to creating a phishing website that tricked a member of this group into providing access to the money they’d made from their scams.

Medayedupin reportedly told investigators that for almost a week after he started emailing his ransom-your-employer scheme, nobody took him up on the offer. But after his name appeared in the news media, he received thousands of inquiries from people interested in his idea.

George described Medayedupin as smart, a quick learner, and fairly dedicated to his work.

“He seems like he could be a fantastic [employee] for a company,” George said. “But there is no employment here, so he chose to do this.”

What’s interesting about this case — and indeed likely why anyone thought this guy worthy of arrest — is that the Nigerian authorities were fairly swift to take action when a domestic cybercriminal raised the specter of causing financial losses for its own banks.

After all, the majority of the cybercrime that originates from Africa — think romance scams, Business Email Compromise (BEC) fraud, and unemployment/pandemic loan fraud — does not target Nigerian citizens, nor does it harm African banks. On the contrary: This activity pumps a great deal of Western money into Nigeria.

How much money are we talking about? The financial losses from these scams dwarf other fraud categories — such as identity theft or credit card fraud. According to the FBI’s Internet Crime Complaint Center (IC3), consumers and businesses reported more than $4.2 billion in losses tied to cybercrime in 2020, and BEC fraud and romance scams alone accounted for nearly 60 percent of those losses.

Source: FBI/IC3 2020 Internet Crime Report.

If the influx of a few billion US dollars into the Nigerian economy each year from cybercrime seems somehow insignificant, consider that (according to George) the average police officer in the country makes the equivalent of less than USD $100 a month.

Ronnie Tokazowski is a threat researcher at Agari, a security firm that has closely tracked many of the groups behind BEC scams. Tokazowski maintains he has been one of the more vocal proponents of the idea that trying to fight these problems by arresting those involved is something of a Sisyphean task, and that it makes way more sense to focus on changing the economic realities in places like Nigeria.

Nigeria has the world’s second-highest unemployment rate — rising from 27.1 percent in 2019 to 33 percent in 2020, according to the National Bureau of Statistics. The nation also is among the world’s most corrupt, according to 2020 findings from Transparency International.

“Education is definitely one piece, as raising awareness is hands down the best way to get ahead of this,” Tokazowski said, in a June 2021 interview. “But we also need to think about ways to create more business opportunities there so that people who are doing this to put food on the table have more legitimate opportunities. Unfortunately, thanks to the level of corruption of government officials, there are a lot of cultural reasons that fighting this type of crime at the source is going to be difficult.”

The ‘Zelle Fraud’ Scam: How it Works, How to Fight Back

19 November 2021 at 21:36

One of the more common ways cybercriminals cash out access to bank accounts involves draining the victim’s funds via Zelle, a “peer-to-peer” (P2P) payment service used by many financial institutions that allows customers to quickly send cash to friends and family. Naturally, a great deal of phishing schemes that precede these bank account takeovers begin with a spoofed text message from the target’s bank warning about a suspicious Zelle transfer. What follows is a deep dive into how this increasingly clever Zelle fraud scam typically works, and what victims can do about it.

Last week’s story warned that scammers are blasting out text messages about suspicious bank transfers as a pretext for immediately calling and scamming anyone who responds via text. Here’s what one of those scam messages looks like:

Anyone who responds “yes,” “no” or at all will very soon after receive a phone call from a scammer pretending to be from the financial institution’s fraud department. The caller’s number will be spoofed so that it appears to be coming from the victim’s bank.

To “verify the identity” of the customer, the fraudster asks for their online banking username, and then tells the customer to read back a passcode sent via text or email. In reality, the fraudster initiates a transaction — such as the “forgot password” feature on the financial institution’s site — which is what generates the authentication passcode delivered to the member.

Ken Otsuka is a senior risk consultant at CUNA Mutual Group, an insurance company that provides financial services to credit unions. Otsuka said a phone fraudster typically will say something like, “Before I get into the details, I need to verify that I’m speaking to the right person. What’s your username?”

“In the background, they’re using the username with the forgot password feature, and that’s going to generate one of these two-factor authentication passcodes,” Otsuka said. “Then the fraudster will say, ‘I’m going to send you the password and you’re going to read it back to me over the phone.'”

The fraudster then uses the code to complete the password reset process, and then changes the victim’s online banking password. The fraudster then uses Zelle to transfer the victim’s funds to others.

An important aspect of this scam is that the fraudsters never even need to know or phish the victim’s password. By sharing their username and reading back the one-time code sent to them via email, the victim is allowing the fraudster to reset their online banking password.

Otsuka said in far too many account takeover cases, the victim has never even heard of Zelle, nor did they realize they could move money that way.

“The thing is, many credit unions offer it by default as part of online banking,” Otsuka said. “Members don’t have to request to use Zelle. It’s just there, and with a lot of members targeted in these scams, although they’d legitimately enrolled in online banking, they’d never used Zelle before.” [Curious if your financial institution uses Zelle? Check out their partner list here].

Otsuka said credit unions offering other peer-to-peer banking products have also been targeted, but that fraudsters prefer to target Zelle due to the speed of the payments.

“The fraud losses can escalate quickly due to the sheer number of members that can be targeted on a single day over the course of consecutive days,” Otsuka said.

To combat this scam Zelle introduced out-of-band authentication with transaction details. This involves sending the member a text containing the details of a Zelle transfer – payee and dollar amount – that is initiated by the member. The member must authorize the transfer by replying to the text.

Unfortunately, Otsuka said, the scammers are defeating this layered security control as well.

“The fraudsters follow the same tactics except they may keep the members on the phone after getting their username and 2-step authentication passcode to login to the accounts,” he said. “The fraudster tells the member they will receive a text containing details of a Zelle transfer and the member must authorize the transaction under the guise that it is for reversing the fraudulent debit card transaction(s).”

In this scenario, the fraudster actually enters a Zelle transfer that triggers the following text to the member, which the member is asked to authorize: For example:

“Send $200 Zelle payment to Boris Badenov? Reply YES to send, NO to cancel. ABC Credit Union . STOP to end all messages.”

“My team has consulted with several credit unions that rolled Zelle out or our planning to introduce Zelle,” Otsuka said. “We found that several credit unions were hit with the scam the same month they rolled it out.”

The upshot of all this is that many financial institutions will claim they’re not required to reimburse the customer for financial losses related to these voice phishing schemes. Bob Sullivan, a veteran journalist who writes about fraud and consumer issues, says in many cases banks are giving customers incorrect and self-serving opinions after the thefts.

“Consumers — many who never ever realized they had a Zelle account – then call their banks, expecting they’ll be covered by credit-card-like protections, only to face disappointment and in some cases, financial ruin,” Sullivan wrote in a recent Substack post. “Consumers who suffer unauthorized transactions are entitled to Regulation E protection, and banks are required to refund the stolen money. This isn’t a controversial opinion, and it was recently affirmed by the CFPB here. If you are reading this story and fighting with your bank, start by providing that link to the financial institution.”

“If a criminal initiates a Zelle transfer — even if the criminal manipulates a victim into sharing login credentials — that fraud is covered by Regulation E, and banks should restore the stolen funds,” Sullivan said. “If a consumer initiates the transfer under false pretenses, the case for redress is more weak.”

Sullivan notes that the Consumer Financial Protection Bureau (CFPB) recently announced it was conducting a probe into companies operating payments systems in the United States, with a special focus on platforms that offer fast, person-to-person payments.

“Consumers expect certain assurances when dealing with companies that move their money,” the CFPB said in its Oct. 21 notice. “They expect to be protected from fraud and payments made in error, for their data and privacy to be protected and not shared without their consent, to have responsive customer service, and to be treated equally under relevant law. The orders seek to understand the robustness with which payment platforms prioritize consumer protection under law.”

Anyone interested in letting the CFPB know about a fraud scam that abused a P2P payment platform like Zelle, Cashapp, or Venmo, for example, should send an email describing the incident to [email protected] Be sure to include Docket No. CFPB-2021-0017 in the subject line of the message.

In the meantime, remember the mantra: Hang up, Look Up, and Call Back. If you receive a call from someone warning about fraud, hang up. If you believe the call might be legitimate, look up the number of the organization supposedly calling you, and call them back.

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