Raspberry Robin: Highly Evasive Worm Spreads over External Disks By Onur Mustafa Erdogan Published: 2022-08-09 · Archived: 2026-04-05 21:20:29 UTC Introduction During our threat hunting exercises in recent months, we’ve started to observe a distinguishing pattern of msiexec.exe usage across different endpoints. As we drilled down to individual assets, we found traces of a recently discovered malware called Raspberry Robin. The RedCanary Research Team first coined the name for this malware in their blog post, and Sekoia published a Flash Report about the activity under the name of QNAP Worm. Both articles offer great analysis of the malware’s behavior. Our findings support and enrich prior research on the topic. Execution Chain Raspberry Robin is a worm that spreads over an external drive. After initial infection, it downloads its payload through msiexec.exe from QNAP cloud accounts, executes its code through rundll32.exe, and establishes a command and control (C2) channel through TOR connections. Image 1: Execution chain of Raspberry Robin Let’s walkthrough the steps of the kill-chain to see how this malware functions. Delivery and Exploitation Raspberry Robin is delivered through infected external disks. Once attached, cmd.exe tries to execute commands from a file within that disk. This file is either a .lnk file or a file with a specific naming pattern. Files with this pattern exhibit a 2 to 5 character name with an usually obscure extension, including .swy, .chk, .ico, .usb, .xml, and .cfg. Also, the attacker uses an excessive amount of whitespace/non printable characters and changing letter case to avoid string matching detection techniques. Example command lines include: C:\Windows\System32\cmd.exe [redacted whitespace/non printable characters] /RCmD