Kroll Employee SIM-Swapped for Crypto Investor Data

August 25, 2023

Security consulting giant Kroll disclosed today that a SIM-swapping attack against one of its employees led to the theft of user information for multiple cryptocurrency platforms that are relying on Kroll services in their ongoing bankruptcy proceedings. And there are indications that fraudsters may already be exploiting the stolen data in phishing attacks.

Cryptocurrency lender BlockFi and the now-collapsed crypto trading platform FTX each disclosed data breaches this week thanks to a recent SIM-swapping attack targeting an employee of Kroll — the company handling both firms’ bankruptcy restructuring.

In a statement released today, New York City-based Kroll said it was informed that on Aug. 19, 2023, someone targeted a T-Mobile phone number belonging to a Kroll employee “in a highly sophisticated ‘SIM swapping’ attack.”

“Specifically, T-Mobile, without any authority from or contact with Kroll or its employees, transferred that employee’s phone number to the threat actor’s phone at their request,” the statement continues. “As a result, it appears the threat actor gained access to certain files containing personal information of bankruptcy claimants in the matters of BlockFi, FTX and Genesis.”

T-Mobile has not yet responded to requests for comment.

Countless websites and online services use SMS text messages for both password resets and multi-factor authentication. This means that stealing someone’s phone number often can let cybercriminals hijack the target’s entire digital life in short order — including access to any financial, email and social media accounts tied to that phone number.

SIM-swapping groups will often call employees on their mobile devices, pretend to be someone from the company’s IT department, and then try to get the employee to visit a phishing website that mimics the company’s login page.

Multiple SIM-swapping gangs have had great success using this method to target T-Mobile employees for the purposes of reselling a cybercrime service that can be hired to divert any T-Mobile user’s text messages and phone calls to another device.

In February 2023, KrebsOnSecurity chronicled SIM-swapping attacks claimed by these groups against T-Mobile employees in more than 100 separate incidents in the second half of 2022. The average cost to SIM swap any T-Mobile phone number was approximately $1,500.

The unfortunate result of the SIM-swap against the Kroll employee is that people who had financial ties to BlockFi, FTX, or Genesis now face increased risk of becoming targets of SIM-swapping and phishing attacks themselves.

And there is some indication this is already happening. Multiple readers who said they got breach notices from Kroll today also shared phishing emails they received this morning that spoofed FTX and claimed, “You have been identified as an eligible client to begin withdrawing digital assets from your FTX account.”

A phishing message targeting FTX users that went out en masse today.

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Tourists Give Themselves Away by Looking Up. So Do Most Network Intruders.

August 22, 2023

In large metropolitan areas, tourists are often easy to spot because they’re far more inclined than locals to gaze upward at the surrounding skyscrapers. Security experts say this same tourist dynamic is a dead giveaway in virtually all computer intrusions that lead to devastating attacks like data theft and ransomware, and that more organizations should set simple virtual tripwires that sound the alarm when authorized users and devices are spotted exhibiting this behavior.

In a blog post published last month, Cisco Talos said it was seeing a worrisome “increase in the rate of high-sophistication attacks on network infrastructure.” Cisco’s warning comes amid a flurry of successful data ransom and state-sponsored cyber espionage attacks targeting some of the most well-defended networks on the planet.

But despite their increasing complexity, a great many initial intrusions that lead to data theft could be nipped in the bud if more organizations started looking for the telltale signs of newly-arrived cybercriminals behaving like network tourists, Cisco says.

“One of the most important things to talk about here is that in each of the cases we’ve seen, the threat actors are taking the type of ‘first steps’ that someone who wants to understand (and control) your environment would take,” Cisco’s Hazel Burton wrote. “Examples we have observed include threat actors performing a ‘show config,’ ‘show interface,’ ‘show route,’ ‘show arp table’ and a ‘show CDP neighbor.’ All these actions give the attackers a picture of a router’s perspective of the network, and an understanding of what foothold they have.”

Cisco’s alert concerned espionage attacks from China and Russia that abused vulnerabilities in aging, end-of-life network routers. But at a very important level, it doesn’t matter how or why the attackers got that initial foothold on your network.

It might be zero-day vulnerabilities in your network firewall or file-transfer appliance. Your more immediate and primary concern has to be: How quickly can you detect and detach that initial foothold?

The same tourist behavior that Cisco described attackers exhibiting vis-a-vis older routers is also incredibly common early on in ransomware and data ransom attacks — which often unfurl in secret over days or weeks as attackers methodically identify and compromise a victim’s key network assets.

These virtual hostage situations usually begin with the intruders purchasing access to the target’s network from dark web brokers who resell access to stolen credentials and compromised computers. As a result, when those stolen resources first get used by would-be data thieves, almost invariably the attackers will run a series of basic commands asking the local system to confirm exactly who and where they are on the victim’s network.

This fundamental reality about modern cyberattacks — that cybercriminals almost always orient themselves by “looking up” who and where they are upon entering a foreign network for the first time — forms the business model of an innovative security company called Thinkst, which gives away easy-to-use tripwires or “canaries” that can fire off an alert whenever all sorts of suspicious activity is witnessed.

“Many people have pointed out that there are a handful of commands that are overwhelmingly run by attackers on compromised hosts (and seldom ever by regular users/usage),” the Thinkst website explains. “Reliably alerting when a user on your code-sign server runs whoami.exe can mean the difference between catching a compromise in week-1 (before the attackers dig in) and learning about the attack on CNN.”

These canaries — or “canary tokens” — are meant to be embedded inside regular files, acting much like a web beacon or web bug that tracks when someone opens an email.

The Canary Tokens website from Thinkst Canary lists nearly two-dozen free customizable canaries.

“Imagine doing that, but for file reads, database queries, process executions or patterns in log files,” the Canary Tokens documentation explains. “Canarytokens does all this and more, letting you implant traps in your production systems rather than setting up separate honeypots.”

Thinkst operates alongside a burgeoning industry offering so-called “deception” or “honeypot” services — those designed to confuse, disrupt and entangle network intruders. But in an interview with KrebsOnSecurity, Thinkst founder and CEO Haroon Meer said most deception techniques involve some degree of hubris.

“Meaning, you’ll have deception teams in your network playing spy versus spy with people trying to break in, and it becomes this whole counterintelligence thing,” Meer said. “Nobody really has time for that. Instead, we are saying literally the opposite: That you’ve probably got all these [security improvement] projects that are going to take forever. But while you’re doing all that, just drop these 10 canaries, because everything else is going to take a long time to do.”

The idea here is to lay traps in sensitive areas of your network or web applications where few authorized users should ever trod. Importantly, the canary tokens themselves are useless to an attacker. For example, that AWS canary token sure looks like the digital keys to your cloud, but the token itself offers no access. It’s just a lure for the bad guys, and you get an alert when and if it is ever touched.

One nice thing about canary tokens is that Thinkst gives them away for free. Head over to canarytokens.org, and choose from a drop-down menu of available tokens, including:

-a web bug / URL token, designed to alert when a particular URL is visited;
-a DNS token, which alerts when a hostname is requested;
-an AWS token, which alerts when a specific Amazon Web Services key is used;
-a “custom exe” token, to alert when a specific Windows executable file or DLL is run;
-a “sensitive command” token, to alert when a suspicious Windows command is run.
-a Microsoft Excel/Word token, which alerts when a specific Excel or Word file is accessed. Continue reading

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Karma Catches Up to Global Phishing Service 16Shop

August 17, 2023

You’ve probably never heard of “16Shop,” but there’s a good chance someone using it has tried to phish you.

A 16Shop phishing page spoofing Apple and targeting Japanese users. Image: Akamai.com.

The international police organization INTERPOL said last week it had shuttered the notorious 16Shop, a popular phishing-as-a-service platform launched in 2017 that made it simple for even complete novices to conduct complex and convincing phishing scams. INTERPOL said authorities in Indonesia arrested the 21-year-old proprietor and one of his alleged facilitators, and that a third suspect was apprehended in Japan.

The INTERPOL statement says the platform sold hacking tools to compromise more than 70,000 users in 43 countries. Given how long 16Shop has been around and how many paying customers it enjoyed over the years, that number is almost certainly highly conservative.

Also, the sale of “hacking tools” doesn’t quite capture what 16Shop was all about: It was a fully automated phishing platform that gave its thousands of customers a series of brand-specific phishing kits to use, and provided the domain names needed to host the phishing pages and receive any stolen credentials.

Security experts investigating 16Shop found the service used an application programming interface (API) to manage its users, an innovation that allowed its proprietors to shut off access to customers who failed to pay a monthly fee, or for those attempting to copy or pirate the phishing kit.

16Shop also localized phishing pages in multiple languages, and the service would display relevant phishing content depending on the victim’s geolocation.

Various 16Shop lures for Apple users in different languages. Image: Akamai.

For example, in 2019 McAfee found that for targets in Japan, the 16Shop kit would also collect Web ID and Card Password, while US victims will be asked for their Social Security Number.

“Depending on location, 16Shop will also collect ID numbers (including Civil ID, National ID, and Citizen ID), passport numbers, social insurance numbers, sort codes, and credit limits,” McAfee wrote.

In addition, 16Shop employed various tricks to help its users’ phishing pages stay off the radar of security firms, including a local “blacklist” of Internet addresses tied to security companies, and a feature that allowed users to block entire Internet address ranges from accessing phishing pages.

The INTERPOL announcement does not name any of the suspects arrested in connection with the 16Shop investigation. However, a number of security firms — including Akamai, McAfee and ZeroFox, previously connected the service to a young Indonesian man named Riswanda Noor Saputra, who sold 16Shop under the hacker handle “Devilscream.”

According to the Indonesian security blog Cyberthreat.id, Saputra admitted being the administrator of 16Shop, but told the publication he handed the project off to others by early 2020. Continue reading

Diligere, Equity-Invest Are New Firms of U.K. Con Man

August 14, 2023

John Clifton Davies, a convicted fraudster estimated to have bilked dozens of technology startups out of more than $30 million through phony investment schemes, has a brand new pair of scam companies that are busy dashing startup dreams: A fake investment firm called Equity-Invest[.]ch, and Diligere[.]co.uk, a scam due diligence company that Equity-Invest insists all investment partners use.

A native of the United Kingdom, Mr. Davies absconded from justice before being convicted on multiple counts of fraud in 2015. Prior to his conviction, Davies served 16 months in jail before being cleared on suspicion of murdering his third wife on their honeymoon in India.

The scam artist John Bernard (left) in a recent Zoom call, and a photo of John Clifton Davies from 2015.

John Clifton Davies was convicted in 2015 of swindling businesses throughout the U.K. that were struggling financially and seeking to restructure their debt. For roughly six years, Davies ran a series of firms that pretended to offer insolvency services. Instead, he simply siphoned what little remaining money these companies had, spending the stolen funds on lavish cars, home furnishings, vacations and luxury watches.

In a three-part series published in 2020, KrebsOnSecurity exposed how Davies — wanted by authorities in the U.K. — had fled the country, taken on the surname Bernard, remarried, and moved to his new (and fourth) wife’s hometown in Ukraine.

After eluding justice in the U.K., Davies reinvented himself as The Private Office of John Bernard, pretending to be a billionaire Swiss investor who made his fortunes in the dot-com boom 20 years ago and who was seeking private equity investment opportunities.

In case after case, Bernard would promise to invest millions in hi-tech startups, only to insist that companies pay tens of thousands of dollars worth of due diligence fees up front. However, the due diligence company he insisted on using — another Swiss firm called The Inside Knowledge — also was secretly owned by Bernard, who would invariably pull out of the deal after receiving the due diligence money.

Bernard found a constant stream of new marks by offering extraordinarily generous finders fees to investment brokers who could introduce him to companies seeking an infusion of cash. Inside Knowledge and The Private Office both closed up shop not long after being exposed here in 2020.

In April 2023, KrebsOnSecurity wrote about Codes2You, a recent Davies venture which purports to be a “full cycle software development company” based in the U.K. The company’s website no longer lists any of Davies’ known associates, but the site does still reference software and cloud services tied to those associates — including MySolve, a “multi-feature platform for insolvency practitioners.”

Earlier this month, KrebsOnSecurity heard from an investment broker who found out his client had paid more than $50,000 in due diligence fees related to a supposed multi-million dollar investment offer from a Swiss concern called Equity-Invest[.]ch.

The investment broker, who spoke on condition that neither he nor his client be named, said Equity-Invest began getting cold feet after his client plunked down the due diligence fees.

“Things started to go sideways when the investor purportedly booked a trip to the US to meet the team but canceled last minute because ‘his pregnant wife got in a car accident,'” the broker explained. “After that, he was radio silent until the contract expired.” Continue reading

Microsoft Patch Tuesday, August 2023 Edition

August 8, 2023

Microsoft Corp. today issued software updates to plug more than 70 security holes in its Windows operating systems and related products, including multiple zero-day vulnerabilities currently being exploited in the wild.

Six of the flaws fixed today earned Microsoft’s “critical” rating, meaning malware or miscreants could use them to install software on a vulnerable Windows system without any help from users.

Last month, Microsoft acknowledged a series of zero-day vulnerabilities in a variety of Microsoft products that were discovered and exploited in-the-wild attacks. They were assigned a single placeholder designation of CVE-2023-36884.

Satnam Narang, senior staff research engineer at Tenable, said the August patch batch addresses CVE-2023-36884, which involves bypassing the Windows Search Security feature.

“Microsoft also released ADV230003, a defense-in-depth update designed to stop the attack chain associated that leads to the exploitation of this CVE,” Narang said. “Given that this has already been successfully exploited in the wild as a zero-day, organizations should prioritize patching this vulnerability and applying the defense-in-depth update as soon as possible.”

Redmond patched another flaw that is already seeing active attacks — CVE-2023-38180 — a weakness in .NET and Visual Studio that leads to a denial-of-service condition on vulnerable servers.

“Although the attacker would need to be on the same network as the target system, this vulnerability does not require the attacker to have acquired user privileges,” on the target system, wrote Nikolas Cemerikic, cyber security engineer at Immersive Labs. Continue reading

Meet the Brains Behind the Malware-Friendly AI Chat Service ‘WormGPT’

August 8, 2023

WormGPT, a private new chatbot service advertised as a way to use Artificial Intelligence (AI) to write malicious software without all the pesky prohibitions on such activity enforced by the likes of ChatGPT and Google Bard, has started adding restrictions of its own on how the service can be used. Faced with customers trying to use WormGPT to create ransomware and phishing scams, the 23-year-old Portuguese programmer who created the project now says his service is slowly morphing into “a more controlled environment.”

Image: SlashNext.com.

The large language models (LLMs) made by ChatGPT parent OpenAI or Google or Microsoft all have various safety measures designed to prevent people from abusing them for nefarious purposes — such as creating malware or hate speech. In contrast, WormGPT has promoted itself as a new, uncensored LLM that was created specifically for cybercrime activities.

WormGPT was initially sold exclusively on HackForums, a sprawling, English-language community that has long featured a bustling marketplace for cybercrime tools and services. WormGPT licenses are sold for prices ranging from 500 to 5,000 Euro.

“Introducing my newest creation, ‘WormGPT,’ wrote “Last,” the handle chosen by the HackForums user who is selling the service. “This project aims to provide an alternative to ChatGPT, one that lets you do all sorts of illegal stuff and easily sell it online in the future. Everything blackhat related that you can think of can be done with WormGPT, allowing anyone access to malicious activity without ever leaving the comfort of their home.”

WormGPT’s core developer and frontman “Last” promoting the service on HackForums. Image: SlashNext.

In July, an AI-based security firm called SlashNext analyzed WormGPT and asked it to create a “business email compromise” (BEC) phishing lure that could be used to trick employees into paying a fake invoice.

“The results were unsettling,” SlashNext’s Daniel Kelley wrote. “WormGPT produced an email that was not only remarkably persuasive but also strategically cunning, showcasing its potential for sophisticated phishing and BEC attacks.”

SlashNext asked WormGPT to compose this BEC phishing email. Image: SlashNext.

A review of Last’s posts on HackForums over the years shows this individual has extensive experience creating and using malicious software. In August 2022, Last posted a sales thread for “Arctic Stealer,” a data stealing trojan and keystroke logger that he sold there for many months.

“I’m very experienced with malwares,” Last wrote in a message to another HackForums user last year.

Last has also sold a modified version of the information stealer DCRat, as well as an obfuscation service marketed to malicious coders who sell their creations and wish to insulate them from being modified or copied by customers.

Shortly after joining the forum in early 2021, Last told several different Hackforums users his name was Rafael and that he was from Portugal. HackForums has a feature that allows anyone willing to take the time to dig through a user’s postings to learn when and if that user was previously tied to another account.

That account tracing feature reveals that while Last has used many pseudonyms over the years, he originally used the nickname “ruiunashackers.” The first search result in Google for that unique nickname brings up a TikTok account with the same moniker, and that TikTok account says it is associated with an Instagram account for a Rafael Morais from Porto, a coastal city in northwest Portugal.

AN OPEN BOOK

Reached via Instagram and Telegram, Morais said he was happy to chat about WormGPT.

“You can ask me anything,” Morais said. “I’m an open book.”

Morais said he recently graduated from a polytechnic institute in Portugal, where he earned a degree in information technology. He said only about 30 to 35 percent of the work on WormGPT was his, and that other coders are contributing to the project. So far, he says, roughly 200 customers have paid to use the service.

“I don’t do this for money,” Morais explained. “It was basically a project I thought [was] interesting at the beginning and now I’m maintaining it just to help [the] community. We have updated a lot since the release, our model is now 5 or 6 times better in terms of learning and answer accuracy.”

WormGPT isn’t the only rogue ChatGPT clone advertised as friendly to malware writers and cybercriminals. According to SlashNext, one unsettling trend on the cybercrime forums is evident in discussion threads offering “jailbreaks” for interfaces like ChatGPT.

“These ‘jailbreaks’ are specialised prompts that are becoming increasingly common,” Kelley wrote. “They refer to carefully crafted inputs designed to manipulate interfaces like ChatGPT into generating output that might involve disclosing sensitive information, producing inappropriate content, or even executing harmful code. The proliferation of such practices underscores the rising challenges in maintaining AI security in the face of determined cybercriminals.”

Morais said they have been using the GPT-J 6B model since the service was launched, although he declined to discuss the source of the LLMs that power WormGPT. But he said the data set that informs WormGPT is enormous.

“Anyone that tests wormgpt can see that it has no difference from any other uncensored AI or even chatgpt with jailbreaks,” Morais explained. “The game changer is that our dataset [library] is big.” Continue reading

Teach a Man to Phish and He’s Set for Life

August 4, 2023

One frustrating aspect of email phishing is the frequency with which scammers fall back on tried-and-true methods that really have no business working these days. Like attaching a phishing email to a traditional, clean email message, or leveraging link redirects on LinkedIn, or abusing an encoding method that makes it easy to disguise booby-trapped Microsoft Windows files as relatively harmless documents.

KrebsOnSecurity recently heard from a reader who was puzzled over an email he’d just received saying he needed to review and complete a supplied W-9 tax form. The missive was made to appear as if it were part of a mailbox delivery report from Microsoft 365 about messages that had failed to deliver.

The reader, who asked to remain anonymous, said the phishing message contained an attachment that appeared to have a file extension of “.pdf,” but something about it seemed off. For example, when he downloaded and tried to rename the file, the right arrow key on the keyboard moved his cursor to the left, and vice versa.

The file included in this phishing scam uses what’s known as a “right-to-left override” or RLO character. RLO is a special character within unicode — an encoding system that allows computers to exchange information regardless of the language used — that supports languages written from right to left, such as Arabic and Hebrew.

Look carefully at the screenshot below and you’ll notice that while Microsoft Windows says the file attached to the phishing message is named “lme.pdf,” the full filename is “fdp.eml” spelled backwards. In essence, this is a .eml file — an electronic mail format or email saved in plain text — masquerading as a .PDF file.

“The email came through Microsoft Office 365 with all the detections turned on and was not caught,” the reader continued. “When the same email is sent through Mimecast, Mimecast is smart enough to detect the encoding and it renames the attachment to ‘___fdp.eml.’ One would think Microsoft would have had plenty of time by now to address this.”

Indeed, KrebsOnSecurity first covered RLO-based phishing attacks back in 2011, and even then it wasn’t a new trick.

Opening the .eml file generates a rendering of a webpage that mimics an alert from Microsoft about wayward messages awaiting restoration to your inbox. Clicking on the “Restore Messages” link there bounces you through an open redirect on LinkedIn before forwarding to the phishing webpage.

As noted here last year, scammers have long taken advantage of a marketing feature on the business networking site which lets them create a LinkedIn.com link that bounces your browser to other websites, such as phishing pages that mimic top online brands (but chiefly Linkedin’s parent firm Microsoft). Continue reading

How Malicious Android Apps Slip Into Disguise

August 3, 2023

Researchers say mobile malware purveyors have been abusing a bug in the Google Android platform that lets them sneak malicious code into mobile apps and evade security scanning tools. Google says it has updated its app malware detection mechanisms in response to the new research.

At issue is a mobile malware obfuscation method identified by researchers at ThreatFabric, a security firm based in Amsterdam. Aleksandr Eremin, a senior malware analyst at the company, told KrebsOnSecurity they recently encountered a number of mobile banking trojans abusing a bug present in all Android OS versions that involves corrupting components of an app so that its new evil bits will be ignored as invalid by popular mobile security scanning tools, while the app as a whole gets accepted as valid by Android OS and successfully installed.

“There is malware that is patching the .apk file [the app installation file], so that the platform is still treating it as valid and runs all the malicious actions it’s designed to do, while at the same time a lot of tools designed to unpack and decompile these apps fail to process the code,” Eremin explained.

Eremin said ThreatFabric has seen this malware obfuscation method used a few times in the past, but in April 2023 it started finding many more variants of known mobile malware families leveraging it for stealth. The company has since attributed this increase to a semi-automated malware-as-a-service offering in the cybercrime underground that will obfuscate or “crypt” malicious mobile apps for a fee.

Eremin said Google flagged their initial May 9, 2023 report as “high” severity. More recently, Google awarded them a $5,000 bug bounty, even though it did not technically classify their finding as a security vulnerability.

“This was a unique situation in which the reported issue was not classified as a vulnerability and did not impact the Android Open Source Project (AOSP), but did result in an update to our malware detection mechanisms for apps that might try to abuse this issue,” Google said in a written statement.

Google also acknowledged that some of the tools it makes available to developers — including APK Analyzer — currently fail to parse such malicious applications and treat them as invalid, while still allowing them to be installed on user devices.

“We are investigating possible fixes for developer tools and plan to update our documentation accordingly,” Google’s statement continued.

Image: ThreatFabric.

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Russia Sends Cybersecurity CEO to Jail for 14 Years

July 26, 2023

The Russian government today handed down a treason conviction and 14-year prison sentence on Iyla Sachkov, the former founder and CEO of one of Russia’s largest cybersecurity firms. Sachkov, 37, has been detained for nearly two years under charges that the Kremlin has kept classified and hidden from public view, and he joins a growing roster of former Russian cybercrime fighters who are now serving hard time for farcical treason convictions.

Ilya Sachkov. Image: Group-IB.com.

In 2003, Sachkov founded Group-IB, a cybersecurity and digital forensics company that quickly earned a reputation for exposing and disrupting large-scale cybercrime operations, including quite a few that were based in Russia and stealing from Russian companies and citizens.

In September 2021, the Kremlin issued treason charges against Sachkov, although it has refused to disclose any details about the allegations. Sachkov pleaded not guilty. After a three-week “trial” that was closed to the public, Sachkov was convicted of treason and sentenced to 14 years in prison. Prosecutors had asked for 18 years.

Group-IB relocated its headquarters to Singapore several years ago, although it did not fully exit the Russian market until April 2023. In a statement, Group-IB said that during their founder’s detainment, he was denied the right to communicate — no calls, no letters — with the outside world for the first few months, and was deprived of any visits from family and friends.

“Ultimately, Ilya has been denied a chance for an impartial trial,” reads a blog post on the company’s site. “All the materials of the case are kept classified, and all hearings were held in complete secrecy with no public scrutiny. As a result, we might never know the pretext for his conviction.”

Prior to his arrest in 2021, Sachkov publicly chastised the Kremlin for turning a blind eye to the epidemic of ransomware attacks coming from Russia. In a speech covered by the Financial Times in 2021, Sachkov railed against the likes of Russian hacker Maksim Yakubets, the accused head of a hacking group called Evil Corp. that U.S. officials say has stolen hundreds of millions of dollars over the past decade. Continue reading

Who and What is Behind the Malware Proxy Service SocksEscort?

July 25, 2023

Researchers this month uncovered a two-year-old Linux-based remote access trojan dubbed AVrecon that enslaves Internet routers into botnet that bilks online advertisers and performs password-spraying attacks. Now new findings reveal that AVrecon is the malware engine behind a 12-year-old service called SocksEscort, which rents hacked residential and small business devices to cybercriminals looking to hide their true location online.

Image: Lumen’s Black Lotus Labs.

In a report released July 12, researchers at Lumen’s Black Lotus Labs called the AVrecon botnet “one of the largest botnets targeting small-office/home-office (SOHO) routers seen in recent history,” and a crime machine that has largely evaded public attention since first being spotted in mid-2021.

“The malware has been used to create residential proxy services to shroud malicious activity such as password spraying, web-traffic proxying and ad fraud,” the Lumen researchers wrote.

Malware-based anonymity networks are a major source of unwanted and malicious web traffic directed at online retailers, Internet service providers (ISPs), social networks, email providers and financial institutions. And a great many of these “proxy” networks are marketed primarily to cybercriminals seeking to anonymize their traffic by routing it through an infected PC, router or mobile device.

Proxy services can be used in a legitimate manner for several business purposes — such as price comparisons or sales intelligence — but they are massively abused for hiding cybercrime activity because they make it difficult to trace malicious traffic to its original source. Proxy services also let users appear to be getting online from nearly anywhere in the world, which is useful if you’re a cybercriminal who is trying to impersonate someone from a specific place.

Spur.us, a startup that tracks proxy services, told KrebsOnSecurity that the Internet addresses Lumen tagged as the AVrecon botnet’s “Command and Control” (C2) servers all tie back to a long-running proxy service called SocksEscort.

SocksEscort[.]com, is what’s known as a “SOCKS Proxy” service. The SOCKS (or SOCKS5) protocol allows Internet users to channel their Web traffic through a proxy server, which then passes the information on to the intended destination. From a website’s perspective, the traffic of the proxy network customer appears to originate from a rented/malware-infected PC tied to a residential ISP customer, not from the proxy service customer.

The SocksEscort home page says its services are perfect for people involved in automated online activity that often results in IP addresses getting blocked or banned, such as Craigslist and dating scams, search engine results manipulation, and online surveys.

Spur tracks SocksEscort as a malware-based proxy offering, which means the machines doing the proxying of traffic for SocksEscort customers have been infected with malicious software that turns them into a traffic relay. Usually, these users have no idea their systems are compromised.

Spur says the SocksEscort proxy service requires customers to install a Windows based application in order to access a pool of more than 10,000 hacked devices worldwide.

“We created a fingerprint to identify the call-back infrastructure for SocksEscort proxies,” Spur co-founder Riley Kilmer said. “Looking at network telemetry, we were able to confirm that we saw victims talking back to it on various ports.”

According to Kilmer, AVrecon is the malware that gives SocksEscort its proxies.

“When Lumen released their report and IOCs [indicators of compromise], we queried our system for which proxy service call-back infrastructure overlapped with their IOCs,” Kilmer continued. “The second stage C2s they identified were the same as the IPs we labeled for SocksEscort.”

Lumen’s research team said the purpose of AVrecon appears to be stealing bandwidth – without impacting end-users – in order to create a residential proxy service to help launder malicious activity and avoid attracting the same level of attention from Tor-hidden services or commercially available VPN services.

“This class of cybercrime activity threat may evade detection because it is less likely than a crypto-miner to be noticed by the owner, and it is unlikely to warrant the volume of abuse complaints that internet-wide brute-forcing and DDoS-based botnets typically draw,” Lumen’s Black Lotus researchers wrote.

Preserving bandwidth for both customers and victims was a primary concern for SocksEscort in July 2022, when 911S5 — at the time the world’s largest known malware proxy network — got hacked and imploded just days after being exposed in a story here. Kilmer said after 911’s demise, SocksEscort closed its registration for several months to prevent an influx of new users from swamping the service.

Danny Adamitis, principal information security researcher at Lumen and co-author of the report on AVrecon, confirmed Kilmer’s findings, saying the C2 data matched up with what Spur was seeing for SocksEscort dating back to September 2022.

Adamitis said that on July 13 — the day after Lumen published research on AVrecon and started blocking any traffic to the malware’s control servers — the people responsible for maintaining the botnet reacted quickly to transition infected systems over to a new command and control infrastructure.

“They were clearly reacting and trying to maintain control over components of the botnet,” Adamitis said. “Probably, they wanted to keep that revenue stream going.”

Frustratingly, Lumen was not able to determine how the SOHO devices were being infected with AVrecon. Some possible avenues of infection include exploiting weak or default administrative credentials on routers, and outdated, insecure firmware that has known, exploitable security vulnerabilities.
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