Researchers with IBM Security’s X-Force division have analyzed 13 crypters employed by the cybercrime group behind the infamous TrickBot and Conti malware.
The use of crypters to obfuscate malware in order to evade antivirus detection is not new, but TrickBot’s operators – which are known as Wizard Spider, ITG23, or the Trickbot Group – took this practice to a new level, by automating the crypting of malware at scale with the launch of a Jenkins build server.
The TrickBot malware family emerged in 2016, when it mainly facilitated online banking fraud. The malware has evolved into helping the mass distribution of other malware families, and the cybercrime group behind it has widened its activities as well.
Wizard Spider, IBM says, has expanded operations with the deployment of BazarLoader and Anchor, and stepped deep into the ransomware business, with Diavol, Ryuk, and Conti. The tight connection between Conti and TrickBot has been long known, and a report earlier this year suggested that Conti bought TrickBot sometime around the end of 2021.
“ITG23 is best thought of as a group of groups, not unlike a large corporation, who report to common ‘upper management’ and share infrastructure and support functions, such as IT and human resources. One of these support groups within ITG23 is dedicated to developing crypters for use with the group’s own malware operations as well as for several other groups,” IBM explains.
The cybercrime gang has been encrypting their malware for years, but the development of new crypters suggested that the group was looking to expand the operation. In fact, IBM has discovered evidence showing that, in April 2021, the group set up a Jenkins build server for the automated encryption of malware at scale.
Malware families using Wizard Spider’s crypting service include TrickBot, BazarLoader, Cobalt Strike, Colibri, Emotet, IcedID, Gozi, Qakbot, and Sliver. Ransomware families such as AstroLocker, Conti, MountLocker, and Quantum also use it.
The hacking group discontinued TrickBot in December 2021, and retired BazarLoader in February 2022, but continued to offer its crypters to other malware families. However, the researchers noticed that the gang used a separate crypter – dubbed ShellStarter – for its own Anchor malware.
Some of the information related to the group’s use of crypters was extracted from the files a Ukrainian security researcher leaked via Twitter following Russia’s invasion of Ukraine. The information included conversations between the gang’s members, which were mainly focused on the Conti ransomware.
These conversations also revealed that the individual in charge of the crypting operations was referred to as Bentley, and that the TrickBot group was affiliated with the malware distribution group TA551.