Full Report
A vulnerability in the WinRAR file archiver solution could be exploited to bypass the Mark of the Web (MotW) security warning and execute arbitrary code on a Windows machine. [...]
Analysis Summary
# Vulnerability: WinRAR Symbolic Link Flaw Bypasses Windows Mark of the Web (MotW)
## CVE Details
- CVE ID: CVE-2025-31334
- CVSS Score: 6.8 (Medium)
- CWE: Not explicitly mentioned, related to improper handling of file system links/security metadata.
## Affected Systems
- Products: WinRAR
- Versions: All versions prior to 7.11
- Configurations: Applicable when WinRAR opens a symbolic link (symlink) that points to an executable file. Note: Creating a symlink on Windows typically requires administrator permissions.
## Vulnerability Description
The CVE-2025-31334 vulnerability resides in WinRAR versions before 7.11. It allows a threat actor to bypass the Windows Mark of the Web (MotW) security alert when a user opens an executable file via a specially crafted symbolic link created within an archive opened by WinRAR. The MotW tag, which alerts users about files downloaded from the internet, was ignored for the target executable when launched through this method, potentially leading to arbitrary code execution.
## Exploitation
- Status: Not explicitly stated as exploited in the wild, but context suggests similar flaws are actively exploited by threat actors.
- Complexity: Likely Medium (Requires creating a malicious archive containing a symlink to an executable; creating the symlink itself requires admin rights on the target system).
- Attack Vector: Network (via distributed malicious archives) $\rightarrow$ Local execution.
## Impact
- Confidentiality: Potential (If arbitrary code execution leads to data exfiltration)
- Integrity: High (Allows execution of arbitrary code)
- Availability: Potential (If arbitrary code execution leads to service disruption or system damage)
## Remediation
### Patches
- WinRAR version **7.11** and later.
* *Fix Note: "If symlink pointing at an executable was started from WinRAR shell, the executable Mark of the Web data was ignored"*
### Workarounds
- No specific workarounds were detailed in the provided context other than updating the software. Users should exercise caution when opening executables or archives from untrusted sources.
## Detection
- **Indicators of Compromise:** Execution of unexpected executables following decompression or opening of archives when the MotW warning was absent.
- **Detection methods and tools:** Monitoring system processes for execution originating from archive handling processes, especially when a symlink is involved. Security tools should look for attempts to execute files tagged with MotW metadata being bypassed.
## References
- Vendor Advisory: http://www.win-rar.com/whatsnew.html?&L=0
- Coordination Report (IPA/JVN): jvn.jp/en/jp/JVN59547048/