A group of hackers that target military and government organizations has recently borrowed code from an old online banking Trojan called Carberp, further blurring the line between cybercrime and cyberespionage.
The hacker group is known by various names in the security industry, including Pawn Storm and APT28. Its primary malware tool is a backdoor program called Sednit or Sofacy.
The group has been active since at least 2007 and has targeted governmental, security and military organizations from NATO member countries, as well as defense contractors and media organizations, Ukrainian political activists and Kremlin critics.
It's not clear why such a group would borrow code from a banking Trojan that dates back to 2009. It could be a quick fix to evade detection after its own tool was exposed and documented or could be just a diversion.
Or maybe the Carberp code, which was leaked online in 2013, was really more efficient than what Pawn Storm could create on its own. It was definitely cheaper than writing something from scratch.
The code similarities were spotted by security researchers from antivirus vendor F-Secure, who analyzed the group's recent campaigns.
The new Pawn Storm connection, combined with recent activity from a gang known as Anunak or Carbanak that also uses Carberp-based malware indicates that this old Trojan is still alive and kicking, the F-Secure researchers concluded.
In 2014, the Anunak/Carbanak gang, which also uses targeted attacks instead of mass scale campaigns, managed to infect over 100 financial institutions worldwide and steal $1 billion. According to a report released Tuesday by antivirus vendor ESET, the group has recently returned with new attacks.
Pawn Storm's modus operandi is sophisticated and combines various malware distribution techniques. The group has used spear phishing emails with malicious Microsoft Office documents, websites hosting zero-day exploits, fake Microsoft Outlook Web Access (OWA) login pages and even rogue browser add-ons.
Because its target selection seems to reflect Russia's geopolitical interests, some security researchers believe that the group is sponsored by that country's intelligence agencies.
According to the F-Secure researchers, the Sofacy dropper component that served as payload for Pawn Storm's exploits in recent months is based on the Carberp source code. This is a small DLL file dropped on the system whose purpose is to contact the command-and-control server and download additional components.
"By carefully reverse engineering the DLL, it became apparent that this family is based on the Carberp source code," the F-Secure researchers said Tuesday in a blog post. "Features used by this Sofacy [dropper] based on the Carberp sources include the API resolving algorithm and code injection mechanism. Also, the algorithm used for generating random URLs is loosely based on that of Carberp."
However, there are also major implementation differences between the Sofacy dropper and the publicly leaked Carberp code. This suggests that the Pawn Storm group has access to a more recent version of Carberp or that it continued to develop it privately.
Since 2009 several groups of cybercriminals have used Carberp and most of them were arrested by Russian authorities. The Trojan has been something of an oddity in the cybercrime world because for many years it was only used against online banking users from Russia and former Soviet Union countries.