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Why Malware Crypting Services Deserve More Scrutiny

By BrianKrebs

If you operate a cybercrime business that relies on disseminating malicious software, you probably also spend a good deal of time trying to disguise or “crypt” your malware so that it appears benign to antivirus and security products. In fact, the process of “crypting” malware is sufficiently complex and time-consuming that most serious cybercrooks will outsource this critical function to a handful of trusted third parties. This story explores the history and identity behind Cryptor[.]biz, a long-running crypting service that is trusted by some of the biggest names in cybercrime.

Virtually all malware that is deployed for use in data stealing at some point needs to be crypted. This highly technical, laborious process involves iteratively altering the appearance and behavior of a malicious file until it no longer sets off alarm bells when scanned by different antivirus tools.

Experienced malware purveyors understand that if they’re not continuously crypting their malware before sending it out, then a lot more of whatever digital disease they are trying to spread is going to get flagged by security tools. In short, if you are running a cybercrime enterprise and you’re not equipped to handle this crypting process yourself, you probably need to pay someone else to do it for you.

Thanks to the high demand for reliable crypting services, there are countless cybercriminals who’ve hung out their shingles as crypting service providers. However, most of these people do not appear to be very good at what they do, because most are soon out of business.

One standout is Cryptor[.]biz. This service is actually recommended by the purveyors of the RedLine information stealer malware, which is a popular and powerful malware kit that specializes in stealing victim data and is often used to lay the groundwork for ransomware attacks. Cryptor[.]biz also has been recommended to customers of the Vidar information stealer malware family (via the malware’s Telegram support channels).

WHO RUNS CRYPTOR[.]BIZ?

As good as Cryptor[.]biz may be at obfuscating malware, its proprietor does not appear to have done a great job covering his own tracks. The registration records for the website Cryptor[.]biz are hidden behind privacy protection services, but the site’s homepage says potential customers should register by visiting the domain crypt[.]guru, or by sending a Jabber instant message to the address “masscrypt@exploit.im.”

Crypt[.]guru’s registration records also are hidden, yet passive domain name system (DNS) records for both cryptor[.]biz and crypt[.]guru show that in 2018 the domains were forwarding incoming email to the address obelisk57@gmail.com.

Cyber intelligence firm Intel 471 reports that obelisk57@gmail.com was used to register an account on the forum Blacksoftware under the nickname “Kerens.” Meanwhile, the Jabber address masscrypt@exploit.im has been associated with the user Kerens on the Russian hacking forum Exploit from 2011 to the present day.

The login page for Cryptor dot biz contains several clues about who runs the service.

The very first post by Kerens on Exploit in 2011 was a negative review of a popular crypting service that predated Cryptor[.]biz called VIP Crypt, which Kerens accused of being “shitty” and unreliable. But Intel 471 finds that after his critical review of VIP Crypt, Kerens did not post publicly on Exploit again for another four years until October 2016, when they suddenly began advertising Cryptor[.]biz.

Intel 471 found that Kerens used the email address pepyak@gmail.com, which also was used to register Kerens accounts on the Russian language hacking forums Verified and Damagelab.

Ironically, Verified has itself been hacked multiple times over the years, with its private messages and user registration details leaked online. Those records indicate the user Kerens registered on Verified in March 2009 from an Internet address in Novosibirsk, a city in the southern Siberian region of Russia.

In 2010, someone with the username Pepyak on the Russian language affiliate forum GoFuckBiz[.]com shared that they typically split their time during the year between living in Siberia (during the milder months) and Thailand (when Novosibirsk is typically -15 °C/°5F).

For example, in one conversation about the best car to buy for navigating shoddy roads, Pepyak declared, “We have shitty roads in Siberia.” In January 2010, Pepyak asked the GoFuckBiz community where one might find a good USB-based modem in Phuket, Thailand.

DomainTools.com says the email address pepyak@gmail.com was used to register 28 domain names over the years, including a now-defunct Russian automobile sales website called “autodoska[.]biz.” DomainTools shows this website was registered in 2008 to a Yuri Churnov from Sevastpol, Crimea (prior to Russia’s annexation of Crimea in 2014, the peninsula was part of Ukraine).

The WHOIS records for autodoska[.]biz were changed in 2010 to Sergey Purtov (pepyak@gmail.com) from Yurga, a town in Russia’s Kemerovo Oblast, which is a relatively populous area in Western Siberia that is adjacent to Novosibirsk.

A satellite view of the region including Novosibirsk, Yurga and Kemerovo Oblast. Image: Google Maps.

Many of the 28 domains registered to pepyak@gmail.com have another email address in their registration records: unforgiven57@mail.ru. According to DomainTools, the Unforgiven email address was used to register roughly a dozen domains, including three that were originally registered to Keren’s email address — pepyak@gmail.com (e.g., antivirusxp09[.]com).

One of the domains registered in 2006 to the address unforgiven57@mail.ru was thelib[.]ru, which for many years was a place to download pirated e-books. DomainTools says thelib[.]ru was originally registered to a Sergey U Purtov.

Most of the two-dozen domains registered to pepyak@gmail.com shared a server at one point with a small number of other domains, including mobile-soft[.]su, which was registered to the email address spurtov@gmail.com.

CDEK, an express delivery company based in Novosibirsk, was apparently hacked at some point because cyber intelligence firm Constella Intelligence found that its database shows the email address spurtov@gmail.com was assigned to a Sergey Yurievich Purtov (Сергей Юрьевич Пуртов).

DomainTools says the same phone number in the registration records for autodoska[.]biz (+7.9235059268) was used to secure two other domains — bile[.]ru and thelibrary[.]ru, both of which were registered to a Sergey Y Purtov.

A search on the phone number 79235059268 in Skype reveals these digits belong to a “Sergey” from Novosibirsk with the now-familiar username  — Pepyak.

Bringing things full circle, Constella Intelligence shows that various online accounts tied to the email address unforgiven57@mail.ru frequently relied on the somewhat unique password, “plk139t51z.” Constella says that same password was used for just a handful of other email addresses, including gumboldt@gmail.com.

Hacked customer records from CDEK show gumboldt@gmail.com was tied to a customer named Sergey Yurievich Purtov. DomainTools found that virtually all of the 15 domain names registered to gumboldt@gmail.com (including the aforementioned mobile-soft[.]su) were at one point registered to spurtov@gmail.com.

Intel 471 reports that gumboldt@gmail.com was used in 2009 to register a user by the nickname “Kolumb” on the Russian hacking forum Antichat. From Kolumb’s posts on Antichat, it seems this user was mostly interested in buying access to compromised computers inside of Russia.

Then in December 2009, Kolumb said they were in desperate need of a reliable crypting service or full-time cryptor.

“We need a person who will crypt software every day, sometimes even a couple of times a day,” Kolumb wrote on Antichat.

Mr. Purtov did not respond to requests for comment sent to any of the email addresses referenced in this report. Mail.ru responded that the email address spurtov@mail.ru is no longer active.

ANALYSIS

As KrebsOnSecurity opined on Mastodon earlier this week, it makes a lot of sense for cybersecurity researchers and law enforcement alike to focus attention on the top players in the crypting space — for several reasons. Most critically, the cybercriminals offering time-tested crypting services also tend to be among the most experienced and connected malicious coders on the planet.

Think of it this way: By definition, a crypting service scans and examines all types of malware before those new nasties are first set loose in the wild. This fact alone should make these criminal enterprises a primary target of cybersecurity firms looking to gain more timely intelligence about new malware.

Also, a review of countless posts and private messages from Pepyak and other crypting providers shows that a successful crypting service will have direct and frequent contact with some of the world’s most advanced malware authors.

In short, infiltrating or disrupting a trusted crypting service can be an excellent way to slow down or even sideline a large number of cybercrime operations all at once.

Further reading on the crypting industry:

This Service Helps Malware Authors Fix Flaws in Their Code
Antivirus is Dead: Long Live Antivirus!

911 Proxy Service Implodes After Disclosing Breach

By BrianKrebs

The 911 service as it existed until July 28, 2022.

911[.]re, a proxy service that since 2015 has sold access to hundreds of thousands of Microsoft Windows computers daily, announced this week that it is shutting down in the wake of a data breach that destroyed key components of its business operations. The abrupt closure comes ten days after KrebsOnSecurity published an in-depth look at 911 and its connections to shady pay-per-install affiliate programs that secretly bundled 911’s proxy software with other titles, including “free” utilities and pirated software.

911[.]re is was one of the original “residential proxy” networks, which allow someone to rent a residential IP address to use as a relay for his/her Internet communications, providing anonymity and the advantage of being perceived as a residential user surfing the web.

Residential proxy services are often marketed to people seeking the ability to evade country-specific blocking by the major movie and media streaming providers. But some of them — like 911 — build their networks in part by offering “free VPN” or “free proxy” services that are powered by software which turns the user’s PC into a traffic relay for other users. In this scenario, users indeed get to use a free VPN service, but they are often unaware that doing so will turn their computer into a proxy that lets others use their Internet address to transact online.

From a website’s perspective, the IP traffic of a residential proxy network user appears to originate from the rented residential IP address, not from the proxy service customer. These 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 can make it difficult to trace malicious traffic to its original source.

As noted in KrebsOnSecurity’s July 19 story on 911, the proxy service operated multiple pay-per-install schemes that paid affiliates to surreptitiously bundle the proxy software with other software, continuously generating a steady stream of new proxies for the service.

A cached copy of flashupdate[.]net circa 2016, which shows it was the homepage of a pay-per-install affiliate program that incentivized the silent installation of 911’s proxy software.

Within hours of that story, 911 posted a notice at the top of its site, saying, “We are reviewing our network and adding a series of security measures to prevent misuse of our services. Proxy balance top-up and new user registration are closed. We are reviewing every existing user, to ensure their usage is legit and [in] compliance with our Terms of Service.”

At this announcement, all hell broke loose on various cybercrime forums, where many longtime 911 customers reported they were unable to use the service. Others affected by the outage said it seemed 911 was trying to implement some sort of “know your customer” rules — that maybe 911 was just trying to weed out those customers using the service for high volumes of cybercriminal activity.

Then on July 28, the 911 website began redirecting to a notice saying, “We regret to inform you that we permanently shut down 911 and all its services on July 28th.”

According to 911, the service was hacked in early July, and it was discovered that someone manipulated the balances of a large number of user accounts. 911 said the intruders abused an application programming interface (API) that handles the topping up of accounts when users make financial deposits with the service.

“Not sure how did the hacker get in,” the 911 message reads. “Therefore, we urgently shut down the recharge system, new user registration, and an investigation started.”

The parting message from 911 to its users, posted to the homepage July 28, 2022.

However the intruders got in, 911 said, they managed to also overwrite critical 911[.]re servers, data and backups of that data.

“On July 28th, a large number of users reported that they could not log in the system,” the statement continues. “We found that the data on the server was maliciously damaged by the hacker, resulting in the loss of data and backups. Its [sic] confirmed that the recharge system was also hacked the same way. We were forced to make this difficult decision due to the loss of important data that made the service unrecoverable.”

Operated largely out of China, 911 was an enormously popular service across many cybercrime forums, and it became something akin to critical infrastructure for this community after two of 911’s longtime competitors — malware-based proxy services VIP72 and LuxSocksclosed their doors in the past year.

Now, many on the crime forums who relied on 911 for their operations are wondering aloud whether there are any alternatives that match the scale and utility that 911 offered. The consensus seems to be a resounding “no.”

I’m guessing we may soon learn more about the security incidents that caused 911 to implode. And perhaps other proxy services will spring up to meet what appears to be a burgeoning demand for such services at the moment, with comparatively little supply.

In the meantime, 911’s absence may coincide with a measurable (if only short-lived) reprieve in unwanted traffic to top Internet destinations, including banks, retailers and cryptocurrency platforms, as many former customers of the proxy service scramble to make alternative arrangements.

Riley Kilmer, co-founder of the proxy-tracking service Spur.us, said 911’s network will be difficult to replicate in the short run.

“My speculation is [911’s remaining competitors] are going to get a major boost in the short term, but a new player will eventually come along,” Kilmer said. “None of those are good replacements for LuxSocks or 911. However, they will all allow anyone to use them. For fraud rates, the attempts will continue but through these replacement services which should be easier to monitor and stop. 911 had some very clean IP addresses.”

911 wasn’t the only major proxy provider disclosing a breach this week tied to unauthenticated APIs: On July 28, KrebsOnSecurity reported that internal APIs exposed to the web had leaked the customer database for Microleaves, a proxy service that rotates its customers’ IP addresses every five to ten minutes. That investigation showed Microleaves — like 911 — had a long history of using pay-per-install schemes to spread its proxy software.

A Deep Dive Into the Residential Proxy Service ‘911’

By BrianKrebs

The 911 service as it exists today.

For the past seven years, an online service known as 911 has sold access to hundreds of thousands of Microsoft Windows computers daily, allowing customers to route their Internet traffic through PCs in virtually any country or city around the globe — but predominantly in the United States. 911 says its network is made up entirely of users who voluntarily install its “free VPN” software. But new research shows the proxy service has a long history of purchasing installations via shady “pay-per-install” affiliate marketing schemes, some of which 911 operated on its own.

911[.]re is one of the original “residential proxy” networks, which allow someone to rent a residential IP address to use as a relay for his/her Internet communications, providing anonymity and the advantage of being perceived as a residential user surfing the web.

From a website’s perspective, the IP traffic of a residential proxy network user appears to originate from the rented residential IP address, not from the proxy service customer. These 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 can make it difficult to trace malicious traffic to its original source.

Residential proxy services are often marketed to people seeking the ability to evade country-specific blocking by the major movie and media streaming providers. But some of them — like 911 — build their networks in part by offering “free VPN” or “free proxy” services that are powered by software which turns the user’s PC into a traffic relay for other users. In this scenario, users indeed get to use a free VPN service, but they are often unaware that doing so will turn their computer into a proxy that lets others use their Internet address to transact online.

The current prices for 911’s proxies.

Researchers at the University of Sherbrooke in Canada recently published an analysis of 911, and found there were roughly 120,000 PCs for rent via the service, with the largest number of them located in the United States.

“The 911[.]re network uses at least two free VPN services to lure its users to install a malware-like software that achieves persistence on the user’s computer,” the researchers wrote. “During the research we identified two free VPN services that [use] a subterfuge to lure users to install software that looks legitimate but makes them part of the network. These two software are currently unknown to most if not all antivirus companies.”

A depiction of the Proxygate service. Image: University of Sherbrooke.

The researchers concluded that 911 is supported by a “mid scale botnet-like infrastructure that operates in several networks, such as corporate, government and critical infrastructure.” The Canadian team said they found many of the 911 nodes available for rent were situated within several major US-based universities and colleges, critical infrastructures such as clean water, defense contractors, law enforcement and government networks.

Highlighting the risk that 911 nodes could pose to internal corporate networks, they observed that “the infection of a node enables the 911.re user to access shared resources on the network such as local intranet portals or other services.”

“It also enables the end user to probe the LAN network of the infected node,” the paper continues. “Using the internal router, it would be possible to poison the DNS cache of the LAN router of the infected node, enabling further attacks.”

The 911 user interface, as it existed when the service first launched in 2016.

THE INTERNET NEVER FORGETS

A review of the clues left behind by 911’s early days on the Internet paint a more complete picture of this long-running proxy network. The domain names used by 911 over the years have a few common elements in their original WHOIS registration records, including the address ustraffic@qq.com and a Yunhe Wang from Beijing.

That ustraffic email is tied to a small number of interesting domains, including browsingguard[.]com, cleantraffic[.]net, execlean[.]net, proxygate[.]net, and flashupdate[.]net.

A cached copy of flashupdate[.]net available at the Wayback Machine shows that in 2016 this domain was used for the “ExE Bucks” affiliate program, a pay-per-install business which catered to people already running large collections of hacked computers or compromised websites. Affiliates were paid a set amount for each installation of the software, with higher commissions for installs in more desirable nations, particularly Europe, Canada and the United States.

“We load only one software — it’s a Socks5 proxy program,” read the message to ExE Bucks affiliates. The website said affiliates were free to spread the proxy software by any means available (i.e. “all promotion methods allowed”). The website’s copyright suggests the ExE Bucks affiliate program dates back to 2012.

A cached copy of flashupdate[.]net circa 2016, which shows it was the home of a pay-per-install affiliate program that incentivized the silent installation of its software. “FUD” in the ad above refers to software and download links that are “Fully UnDetectable” as suspicious or malicious by all antivirus software.

Another domain tied to the ustraffic@qq.com email in 2016 was ExeClean[.]net, a service that advertised to cybercriminals seeking to obfuscate their malicious software so that it goes undetected by all or at least most of the major antivirus products on the market.

“Our technology ensures the maximum security from reverse engineering and antivirus detections,” ExEClean promised.

The Exe Clean service made malware look like goodware to antivirus products.

Yet another domain connected to the ustraffic email is p2pshare[.]net, which advertised “free unlimited internet file-sharing platform” for those who agreed to install their software.

p2pshare.net, which bundled 911 proxy with an application that promised access to free unlimited internet file-sharing.

Still more domains associated with ustraffic@qq.com suggest 911’s proxy has been disguised as security updates for video player plugins, including flashplayerupdate[.]xyz, mediaplayerupdate[.]xyz, and videoplayerupdate[.]xyz.

The earliest version of the 911 website available from the Wayback Machine is from 2016. A sister service called proxygate[.]net launched roughly a year prior to 911 as a “free” public test of the budding new residential proxy service. “Basically using clients to route for everyone,” was how Proxygate described itself in 2016.

For more than a year after its founding, the 911 website was written entirely in Simplified Chinese. The service has only ever accepted payment via virtual currencies such as Bitcoin and Monero, as well as Alipay and China UnionPay, both payment platforms based in China.

Initially, the terms and conditions of 911’s “End User License Agreement (EULA) named a company called Wugaa Enterprises LLC, which was registered in California in 2016. Records from the California Secretary of State office show that in November 2016, Wugaa Enterprises said it was in the Internet advertising business, and had named as its CEO as one Nicolae Aurelian Mazgarean of Brasov, Romania.

A search of European VAT numbers shows the same Brasov, RO address tied to an enterprise called PPC Leads SRL (in the context of affiliate-based marketing, “PPC” generally refers to the term “pay-per-click”).

911’s EULA would later change its company name and address in 2017, to International Media Ltd. in the British Virgin Islands. That is the same information currently displayed on the 911 website.

The EULA attached to 911 software downloaded from browsingguard[.]com (tied to the same ustraffic@qq email that registered 911) references a company called Gold Click Limited. According to the UK Companies House, Gold Click Limited was registered in 2016 to a 34-year-old Yunhe Wang from Beijing City. Many of the WHOIS records for the above mentioned domains also include the name Yunhe Wang, or some variation thereof.

In a response to questions from KrebsOnSecurity, 911 said the researchers were wrong, and that 911 has nothing to do with any of the other domains mentioned above.

“We have 911 SDK link and how it works described clearly in the “Terms of use” of affiliated partners products, and we have details of how the community powered network works on our webpages,” read an email response.

“Besides that, for protecting the end users, we banned many domains’ access and blocked the vulnerable ports, e.g. spamming emails, and torrent is not possible from the 911 network,” the reply continued. “Same as scanning and many others…Accessing to the Lan network and router is also blocked. We are monitoring 911 user’s account closely, once any abnormal behavior detected, we suspend the user’s account right away.”

FORUM ACTIVITY?

911 has remained one of the most popular services among denizens of the cybercrime underground for years, becoming almost shorthand for connecting to that “last mile” of cybercrime. Namely, the ability to route one’s malicious traffic through a computer that is geographically close to the consumer whose credit card they’re about to charge at some website, or whose bank account they’re about to empty.

Given the frequency with which 911 has been praised by cybercrooks on the top forums, it was odd to find the proprietors of 911 do not appear to have created any official support account for the service on any of several dozen forums reviewed by this author going back a decade. However there are two cybercriminal identities on the forums that have responded to individual 911 help requests, and who promoted the sale of 911 accounts via their handles.

Both of these identities were active on the crime forum fl.l33t[.]su between 2016 and 2019. The user “Transfer” advertised and sold access to 911 from 2016 to 2018, amid many sales threads where they advertised expensive electronics and other consumer goods that were bought online with stolen credit cards.

In a 2017 discussion on fl.l33t[.]su, the user who picked the handle “527865713” could be seen answering private messages in response to help inquiries seeking someone at 911. That identity is tied to an individual who for years advertised the ability to receive and relay large wire transfers from China.

One ad from this user in 2016 offered a “China wire service” focusing on Western Union payments, where “all transfers are accepted in China.” The service charged 20 percent of all “scam wires,” unauthorized wire transfers resulting from bank account takeovers or scams like CEO impersonation schemes.

911 TODAY

In August 2021, 911’s biggest competitor — a 15-year-old proxy network built on malware-compromised PCs called VIP72abruptly closed up shop. Almost overnight, an overwhelming number of former VIP72 customers began shifting their proxy activities to 911.

The login page for VIP72, until recently 911’s largest competitor.

That’s according to Riley Kilmer, co-founder of Spur.us — a security company that monitors anonymity services. Kilmer said 911 also gained an influx of new customers after the Jan. 2022 closure of LuxSocks, another malware-based proxy network.

“911’s user base skyrocketed after VIP72 and then LuxSocks went away,” Kilmer said. “And it’s not hard to see why. 911 and VIP72 are both Windows-based apps that operate in a similar way, where you buy private access to IPs.”

Kilmer said 911 is interesting because it appears to be based in China, while nearly all of the other major proxy networks are Russian-backed or Russian-based.

“They have two basic methods to get new IPs,” Kilmer said. “The free VPN apps, and the other is trojanized torrents. They’ll re-upload Photoshop and stuff like that so that it’s backdoored with the 911 proxy. They claim the proxy is bundled with legitimate software and that users all agree to their Terms of Service, meanwhile they can hide behind the claim that it was some affiliate who installed the software, not them.”

Kilmer said at last count, 911 had nearly 200,000 proxy nodes for sale, spanning more than 200 countries: The largest geographic concentration is the United States, where more than 42,000 proxies are currently for rent by the service.

PARTING THOUGHTS

Beware of “free” or super low-cost VPN services. Proper VPN services are not cheap to operate, so the revenue for the service has to come from somewhere. And there are countless “free” VPN services that are anything but, as we’ve seen with 911.

In general, the rule of thumb for transacting online is that if you’re not the paying customer, then you and/or your devices are probably the product that’s being sold to others. Many free VPN services will enlist users as VPN nodes for others to use, and some even offset costs by collecting and reselling data from their users.

All VPN providers claim to prioritize the privacy of their users, but many then go on to collect and store all manner of personal and financial data from those customers. Others are fairly opaque about their data collection and retention policies.

I’ve largely avoided wading into the fray about which VPN services are best, but there are so many shady and just plain bad ones out there that I’d be remiss if I didn’t mention one VPN provider whose business practices and transparency of operation consistently distinguish them from the rest. If maintaining your privacy and anonymity are primary concerns for you as a VPN user, check out Mullvad.net.

Let me make clear that KrebsOnSecurity does not have any financial or business ties to this company (for the avoidance of doubt, this post doesn’t even link to them). I mention it only because I’ve long been impressed with their candor and openness, and because Mullvad goes out of its way to discourage customers from sharing personal or financial data.

To that end, Mullvad will even accept mailed payments of cash to fund accounts, quite a rarity these days. More importantly, the service doesn’t ask users to share phone numbers, email addresses or any other personal information. Nor does it require customers to create passwords: Each subscription can be activated just by entering a Mullvad account number (woe to those who lose their account number).

I wish more companies would observe this remarkably economical security practice, which boils down to the mantra, “You don’t have to protect what you don’t collect.”

Update, July 24, 11:15 a.m. ET: 911’s homepage now includes a banner saying the service has halted new registrations and payments. “We are reviewing our network and adding a series of security measures to prevent misuse of our services,” the message reads. “Proxy balance top-up and new user registration are closed. We are reviewing every existing user, to ensure their usage is legit and [in] compliance with our Terms of Service.”

Update, July 30, 10:07 a.m. ET: 911 announced on July 28 that it is permanently closing down, following a series of data breaches this month that 911 says resulted in the deletion of customer data.

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