Emotet, one of the most dangerous email spam botnets in recent history, is being uninstalled today from all infected devices with the help of a malware module delivered in January by law enforcement.

The botnet’s takedown is the result of an international law enforcement action that allowed investigators to take control of the Emotet’s servers and disrupt the malware’s operation.

Emotet was used by the TA542 threat group (aka Mummy Spider) to deploy second-stage malware payloads, including QBot and Trickbot, onto its victims’ compromised computers.

TA542’s attacks usually led to full network compromise and the deployment of ransomware payloads on all infected systems, including ProLock or Egregor by Qbot, and Ryuk and Conti by TrickBot.

How the Emotet uninstaller works

After the takedown operation, law enforcement pushed a new configuration to active Emotet infections so that the malware would begin to use command and control servers controlled by the Bundeskriminalamt, Germany’s federal police agency.

Law enforcement then distributed a new Emotet module in the form of a 32-bit EmotetLoader.dll to all infected systems that will automatically uninstall the malware on April 25th, 2021.

Malwarebytes security researchers Jérôme Segura and Hasherezade took a closer look at the uninstaller module delivered by law enforcement-controlled to Emotet servers.

After changing the system clock on a test machine to trigger the module, they found that it only deletes associated Windows services, autorun Registry keys, and then exits the process, leaving everything else on the compromised devices untouched.

“For this type of approach to be successful over time, it will be important to have as many eyes as possible on these updates and, if possible, the law enforcement agencies involved should release these updates to the open internet so analysts can make sure nothing unwanted is being slipped in,” Marcin Kleczynski, CEO of Malwarebytes, told BleepingComputer.

“That all said, we view this specific instance as a unique situation and encourage our industry partners to view this as an isolated event that required a special solution and not as an opportunity to set policy moving forward.”

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