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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).
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.
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!
A recent scoop by Reuters revealed that mobile apps for the U.S. Army and the Centers for Disease Control and Prevention (CDC) were integrating software that sends visitor data to a Russian company called Pushwoosh, which claims to be based in the United States. But that story omitted an important historical detail about Pushwoosh: In 2013, one of its developers admitted to authoring the Pincer Trojan, malware designed to surreptitiously intercept and forward text messages from Android mobile devices.
Pushwoosh says it is a U.S. based company that provides code for software developers to profile smartphone app users based on their online activity, allowing them to send tailor-made notifications. But a recent investigation by Reuters raised questions about the company’s real location and truthfulness.
The Army told Reuters it removed an app containing Pushwoosh in March, citing “security concerns.” The Army app was used by soldiers at one of the nation’s main combat training bases.
Reuters said the CDC likewise recently removed Pushwoosh code from its app over security concerns, after reporters informed the agency Pushwoosh was not based in the Washington D.C. area — as the company had represented — but was instead operated from Novosibirsk, Russia.
Pushwoosh’s software also was found in apps for “a wide array of international companies, influential nonprofits and government agencies from global consumer goods company Unilever and the Union of European Football Associations (UEFA) to the politically powerful U.S. gun lobby, the National Rifle Association (NRA), and Britain’s Labour Party.”
The company’s founder Max Konev told Reuters Pushwoosh “has no connection with the Russian government of any kind” and that it stores its data in the United States and Germany.
But Reuters found that while Pushwoosh’s social media and U.S. regulatory filings present it as a U.S. company based variously in California, Maryland and Washington, D.C., the company’s employees are located in Novosibirsk, Russia.
Reuters also learned that the company’s address in California does not exist, and that two LinkedIn accounts for Pushwoosh employees in Washington, D.C. were fake.
“Pushwoosh never mentioned it was Russian-based in eight annual filings in the U.S. state of Delaware, where it is registered, an omission which could violate state law,” Reuters reported.
Pushwoosh admitted the LinkedIn profiles were fake, but said they were created by a marketing firm to drum up business for the company — not misrepresent its location.
Pushwoosh told Reuters it used addresses in the Washington, D.C. area to “receive business correspondence” during the coronavirus pandemic. A review of the Pushwoosh founder’s online presence via Constella Intelligence shows his Pushwoosh email address was tied to a phone number in Washington, D.C. that was also connected to email addresses and account profiles for over a dozen other Pushwoosh employees.
Pushwoosh was incorporated in Novosibirsk, Russia in 2016.
The dust-up over Pushwoosh came in part from data gathered by Zach Edwards, a security researcher who until recently worked for the Internet Safety Labs, a nonprofit organization that funds research into online threats.
Edwards said Pushwoosh began as Arello-Mobile, and for several years the two co-branded — appearing side by side at various technology expos. Around 2016, he said, the two companies both started using the Pushwoosh name.
A search on Pushwoosh’s code base shows that one of the company’s longtime developers is a 41-year-old from Novosibirsk named Yuri Shmakov. In 2013, KrebsOnSecurity interviewed Shmakov for the story, “Who Wrote the Pincer Android Trojan?” wherein Shmakov acknowledged writing the malware as a freelance project.
Shmakov told me that, based on the client’s specifications, he suspected it might ultimately be put to nefarious uses. Even so, he completed the job and signed his work by including his nickname in the app’s code.
“I was working on this app for some months, and I was hoping that it would be really helpful,” Shmakov wrote. “[The] idea of this app is that you can set it up as a spam filter…block some calls and SMS remotely, from a Web service. I hoped that this will be [some kind of] blacklist, with logging about blocked [messages/calls]. But of course, I understood that client [did] not really want this.”
Shmakov did not respond to requests for comment. His LinkedIn profile says he stopped working for Arello Mobile in 2016, and that he currently is employed full-time as the Android team leader at an online betting company.
In a blog post responding to the Reuters story, Pushwoosh said it is a privately held company incorporated under the state laws of Delaware, USA, and that Pushwoosh Inc. was never owned by any company registered in the Russian Federation.
“Pushwoosh Inc. used to outsource development parts of the product to the Russian company in Novosibirsk, mentioned in the article,” the company said. “However, in February 2022, Pushwoosh Inc. terminated the contract.”
However, Edwards noted that dozens of developer subdomains on Pushwoosh’s main domain still point to JSC Avantel, an Internet provider based in Novosibirsk, Russia.
Pushwoosh employees posing at a company laser tag event.
Edwards said the U.S. Army’s app had a custom Pushwoosh configuration that did not appear on any other customer implementation.
“It had an extremely custom setup that existed nowhere else,” Edwards said. “Originally, it was an in-app Web browser, where it integrated a Pushwoosh javascript so that any time a user clicked on links, data went out to Pushwoosh and they could push back whatever they wanted through the in-app browser.”
An Army Times article published the day after the Reuters story ran said at least 1,000 people downloaded the app, which “delivered updates for troops at the National Training Center on Fort Irwin, Calif., a critical waypoint for deploying units to test their battlefield prowess before heading overseas.”
In April 2022, roughly 4,500 Army personnel converged on the National Training Center for a war games exercise on how to use lessons learned from Russia’s war against Ukraine to prepare for future fights against a major adversary such as Russia or China.
Edwards said despite Pushwoosh’s many prevarications, the company’s software doesn’t appear to have done anything untoward to its customers or users.
“Nothing they did has been seen to be malicious,” he said. “Other than completely lying about where they are, where their data is being hosted, and where they have infrastructure.”
Edwards also found Pushwoosh’s technology embedded in nearly two dozen mobile apps that were sold to cities and towns across Illinois as a way to help citizens access general information about their local communities and officials.
The Illinois apps that bundled Pushwoosh’s technology were produced by a company called Government 311, which is owned by Bill McCarty, the current director of the Springfield Office of Budget and Management. A 2014 story in The State Journal-Register said Gov 311’s pricing was based on population, and that the app would cost around $2,500 per year for a city with approximately 25,000 people.
McCarty told KrebsOnSecurity that his company stopped using Pushwoosh “years ago,” and that it now relies on its own technology to provide push notifications through its 311 apps.
But Edwards found some of the 311 apps still try to phone home to Pushwoosh, such as the 311 app for Riverton, Ill.
“Riverton ceased being a client several years ago, which [is] probably why their app was never updated to change out Pushwoosh,” McCarty explained. “We are in the process of updating all client apps and a website refresh. As part of that, old unused apps like Riverton 311 will be deleted.”
Edwards said it’s far from clear how many other state and local government apps and Web sites rely on technology that sends user data to U.S. adversaries overseas. In July, Congress introduced an amended version of the Intelligence Authorization Act for 2023, which included a new section focusing on data drawn from online ad auctions that could be used to geolocate individuals or gain other information about them.
Business Insider reports that if this section makes it into the final version — which the Senate also has to pass — the Office for the Director of National Intelligence (ODNI) will have 60 days after the Act becomes law to produce a risk assessment. The assessment will look into “the counterintelligence risks of, and the exposure of intelligence community personnel to, tracking by foreign adversaries through advertising technology data,” the Act states.
Edwards says he’s hoping those changes pass, because what he found with Pushwoosh is likely just a drop in a bucket.
“I’m hoping that Congress acts on that,” he said. “If they were to put a requirement that there’s an annual audit of risks from foreign ad tech, that would at least force people to identify and document those connections.”
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