CyberSecurity news
FlagThis
@The DefendOps Diaries
//
A critical security flaw, identified as CVE-2025-31334, has been discovered in WinRAR versions prior to 7.11. This vulnerability allows attackers to bypass Windows' Mark of the Web (MotW) security feature using symlinks. MotW is designed to warn users about potentially unsafe files downloaded from the internet, but this flaw enables the silent execution of malicious code without any warning prompts, essentially rendering the MotW security layer ineffective. This issue underscores the importance of timely software updates and robust security practices to protect against evolving cyber threats.
WinRAR, a widely used file archiver, has a history of security vulnerabilities. Previous exploits, such as the ACE file format vulnerability, have allowed attackers to execute malicious code with minimal user interaction. The current flaw, CVE-2025-31334, involves using symlinks within RAR archives to point to executable files. When these executables are launched from the WinRAR shell, the MotW data is ignored, allowing arbitrary code execution without user awareness. This vulnerability highlights a weakness in Microsoft's layered security model, as it can be bypassed by exploiting the fragmented trust between different components of the operating system.
The vulnerability was responsibly disclosed by Shimamine Taihei through Japan’s Information Technology Promotion Agency and has been addressed in WinRAR version 7.11. The update included a fix to ensure that WinRAR respects the MotW tag on symlinked executables. Users are strongly advised to update to the latest version of WinRAR to mitigate the risk. Bypassing MotW is a tactic already exploited by malicious actors, highlighting the need for continuous vigilance and prompt patching to maintain system security.
ImgSrc: thedefendopsdia
References :
WinRAR, a widely used file archiver, has a history of security vulnerabilities. Previous exploits, such as the ACE file format vulnerability, have allowed attackers to execute malicious code with minimal user interaction. The current flaw, CVE-2025-31334, involves using symlinks within RAR archives to point to executable files. When these executables are launched from the WinRAR shell, the MotW data is ignored, allowing arbitrary code execution without user awareness. This vulnerability highlights a weakness in Microsoft's layered security model, as it can be bypassed by exploiting the fragmented trust between different components of the operating system.
The vulnerability was responsibly disclosed by Shimamine Taihei through Japan’s Information Technology Promotion Agency and has been addressed in WinRAR version 7.11. The update included a fix to ensure that WinRAR respects the MotW tag on symlinked executables. Users are strongly advised to update to the latest version of WinRAR to mitigate the risk. Bypassing MotW is a tactic already exploited by malicious actors, highlighting the need for continuous vigilance and prompt patching to maintain system security.
ImgSrc: thedefendopsdia
Share:
References :
- The DefendOps Diaries: Understanding WinRAR Vulnerabilities: A Closer Look at CVE-2025-31334
- Sam Bent: WinRAR Exploit Lets Malware Bypass Windows Security Without Warning
- BleepingComputer: WinRAR flaw bypasses Windows Mark of the Web security alerts
- www.techradar.com: Still using WinRAR? It has a worrying security flaw that could let hackers hijack your Windows device
Classification:
- HashTags: #WinRAR #SecurityFlaw #MalwareBypass
- Company: Microsoft
- Target: Windows Users
- Product: WinRAR
- Feature: Symlink Vulnerability
- Type: Vulnerability
- Severity: Medium