Roughly one million computers were freed of the Emotet malware in April this year, but the botnet might reappear, as the Trojan’s developers have apparently started distributing it again.
Emotet, which emerged in 2014, became one of the most prevalent threats of the decade, evolving into a malware downloader that allowed cybercriminals to disseminate malware such as TrickBot, the Ryuk ransomware, and the QakBot banking Trojan, as well as various other threats.
In January 2021, law enforcement agencies announced they were able to take down Emotet as part of a global operation, and in April the Dutch police issued an uninstall command to clean up roughly one million computers.
Over the weekend, however, security researchers have observed signs that Emotet’s developers are attempting to resurrect the botnet, leveraging their partnership with TrickBot for that.
Security researchers with G Data say they are highly confident that a DLL that TrickBot was observed distributing on Sunday is Emotet, and also note that the samples were compiled just before the deployment: “timestamp : 6191769A (Sun Nov 14 20:50:34 2021).”
The researchers note that, while the network traffic associated with the sample is highly similar to that previously observed for the malware, the encryption is different and HTTPS with a self-signed server certificate is now used.
Furthermore, flattened control flows continue to be used for code obfuscation within the sample, which strengthens the researchers’ assumption that Emotet is attempting a return.
It appears that, for the time being, Emotet’s developers are only looking to rebuild the botnet, but it might not be too long before the threat is back at distributing malware, as it did before.