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.
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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.