A new Windows malware with worm capabilities has been identified by Red Canary intelligence investigators, and it spreads via external USB sticks. This malware is associated with the Raspberry Robin malware cluster, which was initially discovered in September 2021. (cybersecurity firm Sekoia tracks this malware as "QNAP worm"). 

The worm was discovered in many customers' networks by Red Canary's Detection Engineering team, including companies in the technology and manufacturing sectors. When a USB drive carrying a malicious.LNK file is attached, Raspberry Robin spreads to new Windows systems.

The worm launches a new process using cmd.exe to launch a malicious file stored on the infected drive after it has been attached. It reaches out to its command-and-control (C2) servers via Microsoft Standard Installer (msiexec.exe), which are most likely hosted on infected QNAP devices and utilise TOR exit nodes as additional C2 infrastructure. 

The researchers said, "While msiexec.exe downloads and executes legitimate installer packages, adversaries also leverage it to deliver malware. Raspberry Robin uses msiexec.exe to attempt external network communication to a malicious domain for C2 purposes." 

They believe the malware downloads a malicious DLL file [1, 2] on affected workstations to resist eradication between restarts, albeit they haven't determined how it achieves persistence. This DLL is started by Raspberry Robin using two other trusted Windows utilities: fodhelper (a trusted binary for controlling features in Windows settings) and odbcconf (a tool for configuring ODBC drivers). 

The first permits it to get through User Account Control (UAC), while the second assists in the execution and configuration of the DLL. While Red Canary analysts have been able to extensively examine what the newly found malware performs on affected systems, some questions remain unanswered. 

The researchers stated, "First and foremost, we don't know how or where Raspberry Robin infects external drives to perpetuate its activity, though it's likely this occurs offline or otherwise outside of our visibility. We also don't know why Raspberry Robin installs a malicious DLL. One hypothesis is that it may be an attempt to establish persistence on an infected system, though additional information is required to build confidence in that hypothesis." 

Red Canary's report contains more technical details on the Raspberry Robin worm, including indicators of compromise (IOCs) and an ATT&CK of this malware.