CVE-2025-31334: Rarlab WinRAR Mark of the Web RCE Flaw

CVE-2025-31334 Overview

Issue that bypasses the "Mark of the Web" security warning function for files when opening a symbolic link that points to an executable file exists in WinRAR versions prior to 7.11. If a symbolic link specially crafted by an attacker is opened on the affected product, arbitrary code may be executed.

Critical Impact

Attackers can execute arbitrary code which can compromise system integrity and allow unauthorized access.

Affected Products

• WinRAR versions prior to 7.11

Discovery Timeline

• Not Available - Vulnerability discovered by Not Available
• Not Available - Responsible disclosure to Rarlab
• Not Available - CVE CVE-2025-31334 assigned
• Not Available - Rarlab releases security patch
• 2025-04-03 - CVE CVE-2025-31334 published to NVD
• 2025-07-01 - Last updated in NVD database

Technical Details for CVE-2025-31334

Vulnerability Analysis

The vulnerability exists due to improper handling of symbolic links in WinRAR. When a specially crafted symbolic link pointing to an executable is opened, WinRAR bypasses the "Mark of the Web" warning, allowing malicious code execution.

Root Cause

This flaw stems from WinRAR's incorrect processing of symbolic links, leading to a failure in enforcing security warnings designed to protect the system from running unverified executables.

Attack Vector

The attack requires the victim to open a symbolic link within WinRAR. This vector is exploitable remotely through social engineering tactics.

# Example exploitation code (sanitized)
import os

# Create a malicious symlink
os.symlink('/path/to/malicious/executable', 
           'dangerous_link.lnk')

# When opened, this link could execute the malicious code

Detection Methods for CVE-2025-31334

Indicators of Compromise

• Unexplained symbolic links in archive files
• Suspicious files executing upon archive extraction
• Unexpected network connections initiated by WinRAR

Detection Strategies

Implement heuristic-based and signature-based detection of symbolic link exploitation in archived files. Monitor the execution of files extracted from archives, especially when marked as downloaded from the internet.

Monitoring Recommendations

Continuously monitor file system changes related to symbolic links and track the execution of programs launched by WinRAR. Use endpoint detection solutions to flag suspicious activities stemming from WinRAR use.

How to Mitigate CVE-2025-31334

Immediate Actions Required

• Advise users not to open archives from untrusted sources.
• Conduct regular security training focusing on social engineering.
• Review system and application logs for anomalies related to archive handling.

Patch Information

Upgrade to WinRAR version 7.11 or later, which contains the necessary fixes to address this vulnerability.

Workarounds

Ensure that symbolic links within archives are disabled from being executed automatically. Alternatively, require additional user verification before executing any files extracted from an archive.

# Configuration example to remove execution permissions
find /path/to/extracted -type l -exec chmod -x {} \;