A security flaw in the WinRAR file archiver solution might be used to circumvent the Mark of the Web (MotW) security warning and execute arbitrary code on a Windows computer. The vulnerability is known as CVE-2025-31334 and impacts all WinRAR versions except the most recent release, 7.11.
Mark of the Web is a security mechanism in Windows that uses a metadata value (an additional data stream called 'zone-identifier') to identify potentially dangerous files downloaded from the internet. When you launch an executable with the MotW tag, Windows informs you that it was obtained from the internet and can be risky, and you can choose whether to continue or terminate it.
Symlink to executable
The CVE-2025-31334 flaw allows an attacker to circumvent the MotW security warning when opening a symbolic link (symlink) to an executable file in any WinRAR version prior to 7.11. Using a specially designed symbolic link, an attacker can execute arbitrary code.
It should be noted that on Windows, symlinks can only be generated with administrator privileges.
The security flaw received a medium severity score of 6.8 and was fixed in the latest version of WinRAR, according to the applications change log: “If symlink pointing at an executable was started from WinRAR shell, the executable Mark of the Web data was ignored” - WinRaR.
Shimamine Taihei of Mitsui Bussan Secure Directions reported the vulnerability to the Information Technology Promotion Agency (IPA) in Japan. The responsible disclosure was organised by Japan's Computer Security Incident Response Team with the developer of WinRAR.
Starting with version 7.10, WinRAR allows you to remove information from the MotW alternative data stream (such as location and IP address) that could be deemed a privacy issue. Cybercriminals, including state-sponsored ones, have previously used MotW bypasses to transmit malware without triggering the security warning.
Recently, Russian attackers exploited a vulnerability in the 7-Zip archiver that did not propagate the MotW when double archiving (archiving one file within another) to launch the Smokeloader malware dropper.
