Ethical Hacking News
A critical security flaw has been discovered in WinRAR, allowing malicious actors to bypass the Mark of the Web security warning and execute arbitrary code on Windows machines. The vulnerability, tracked as CVE-2025-31334, affects all WinRAR versions except for the latest release, which is currently 7.11. Users are urged to update to the latest version of WinRAR immediately to prevent potential exploitation.
WinRAR has a critical security flaw (CVE-2025-31334) that can bypass Mark of the Web (MotW) security warning. The vulnerability affects all WinRAR versions except for version 7.11. A specially crafted symbolic link can be used to exploit this vulnerability. Thousands of users may have already fallen victim to this exploit without realizing it. Users are advised to update to the latest version of WinRAR as soon as possible. Similar MotW bypasses have been exploited by threat actors in the past to deliver malware. Users must take precautions, such as keeping their software up to date and being cautious when opening executable files from unknown sources.
WinRAR, a popular file archiver solution, has been found to have a critical security flaw that can be exploited to bypass the Mark of the Web (MotW) security warning. This vulnerability, tracked as CVE-2025-31334, affects all WinRAR versions except for the most recent release, which is currently 7.11.
Mark of the Web is a security function in Windows that serves as a metadata value, known as an alternate data stream named ‘zone-identifier’, to tag files as potentially unsafe when downloaded from the internet. When opening an executable with the MotW tag, Windows warns users that it was downloaded from the internet and could be harmful, offering them the option to continue execution or terminate it.
However, researchers have discovered a way to bypass this security warning by using a specially crafted symbolic link. This vulnerability can be exploited in any WinRAR version before 7.11, which means that thousands of users may have already fallen victim to this exploit without realizing it. It is essential for users to update to the latest version of WinRAR as soon as possible.
The vulnerability was reported by Shimamine Taihei of Mitsui Bussan Secure Directions through the Information Technology Promotion Agency (IPA) in Japan. The researchers worked closely with WinRAR's developer, and starting from version 7.10, WinRAR provides the possibility to remove MotW alternate data stream information that could be considered a privacy risk.
Threat actors have exploited similar MotW bypasses in the past to deliver various malware without triggering the security warning. For example, recently Russian hackers leveraged such a vulnerability in the 7-Zip archiver to run Smokeloader malware dropper.
In light of this critical security flaw, it is essential for users to take precautions when using WinRAR. This includes keeping their software up to date and being cautious when opening executable files from unknown sources.
Furthermore, this vulnerability highlights the importance of robust cybersecurity measures in preventing malicious activities such as ransomware attacks and malware distribution.
The discovery of this security flaw underscores the need for ongoing vigilance and the importance of staying informed about the latest security updates and patches. Users must remain vigilant and take proactive steps to protect themselves against such vulnerabilities.
Related Information:
https://www.ethicalhackingnews.com/articles/A-Critical-Security-Flaw-Exposed-How-WinRARs-Mark-of-the-Web-Vulnerability-Can-Be-Exploited-ehn.shtml
https://www.bleepingcomputer.com/news/security/winrar-flaw-bypasses-windows-mark-of-the-web-security-alerts/
https://cybersecuritynews.com/winrar-mark-of-the-web-bypass-vulnerability/
Published: Sat Apr 5 10:44:23 2025 by llama3.2 3B Q4_K_M
