Researchers have identified functional similarities between a malicious component used in the Raspberry Robin infection chain and a Dridex malware loader, further strengthening the operators' connections to the Russia-based Evil Corp group.
The findings suggest that "Evil Corp is likely using Raspberry Robin infrastructure to carry out its attacks," IBM Security X-Force researcher Kevin Henson said in a Thursday analysis.
Raspberry Robin (aka QNAP Worm), first discovered by cybersecurity company Red Canary in September 2021, has remained something of a mystery for nearly a year, partly owing to the noticeable lack of post-exploitation activities in the wild.
That changed in July 2022 when Microsoft revealed that it observed the FakeUpdates (aka SocGholish) malware being delivered via existing Raspberry Robin infections, with potential connections identified between DEV-0206 and DEV-0243 (aka Evil Corp).
The malware is known to be delivered from a compromised system via infected USB devices containing a malicious .LNK file to other devices in the target network. The Windows Shortcut files are designed to retrieve a malicious DLL from a remote server.
"The Raspberry Robin loaders are DLLs that decode and execute an intermediate loader," Henson said. "The intermediate loader performs hook detection as an anti-analysis technique, decodes its strings at runtime and then decodes a highly obfuscated DLL whose purpose has not been determined."
Furthermore, IBM Security X-Force's comparative analysis of a 32-bit Raspberry Robin loader and a 64-bit Dridex loader uncovered overlaps in functionality and structure, with both components incorporating similar anti-analysis code and decoding the final payload in an analogous manner.
Dridex (aka Bugat or Cridex) is the handiwork of Evil Corp and refers to a banking trojan with capabilities to steal information, deploy additional malware such as ransomware, and enslave compromised Windows machines into a botnet.
To mitigate Raspberry Robin infections, it's recommended that organizations monitor USB device connections and disable the AutoRun feature in the Windows operating system settings.