If you’re still using WinRAR, watch out for this dangerous exploit – and please stop

Scammers have been found trying to distribute the VenomRAT malware, by disguising it as a proof-of-concept (PoC) for a newly discovered WinRAR vulnerability.

Cybersecurity researchers from Unit 42 (Palo Alto Networks) recently found a piece of code uploaded to GitHub, claiming to be a PoC for CVE-2023-40477. This is a flaw that allows threat actors to run arbitrary code on target endpoints if the victims run a custom-tailored RAR file in WinRAR older than version 6.23. 

This vulnerability was discovered by Trend Micro’s Zero Day Initiative in early June 2023, and fixed in early August, with version 6.23 of the popular archiving program.


However, soon after public disclosure of the flaw, a malicious actor uploaded a piece of code on GitHub, claiming it to be a PoC for the flaw. The upload even came with a readme file and a video demonstration on how to use the tool. 

In reality, though, the code just downloads an encoded PowerShell script which, in turn, downloads the VenomRAT malware. This malware does a number of things, including logging all key presses and listing installed apps and active processes. The malware can be used to deploy other payloads, and steal credentials, BleepingComputer warns, urging everyone who executed this fake PoC to change their passwords for all sites and environments they use.

Unit 42’s researchers also said that the threat actor’s infrastructure was in place long before the payload was deployed to GitHub, implying that they might try the same thing in the future, with a different vulnerability. The user account that uploaded the fake PoC is now inactive, it was added. 

GitHub is an extremely popular code repository and as such, a major target for hackers. Most of the time, they try to trick developers into downloading malware through typosquatting and impersonation.

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