CVE-2023-46587
📋 TL;DR
A buffer overflow vulnerability in XnView Classic v2.51.5 allows local attackers to execute arbitrary code by opening a specially crafted TIF file. This affects users who process untrusted TIF files with this specific version of the software. The vulnerability requires local access to the system where XnView is installed.
💻 Affected Systems
- XnView Classic
📦 What is this software?
Xnview by Xnview
⚠️ Risk & Real-World Impact
Worst Case
Complete system compromise with attacker gaining full control of the local machine, potentially leading to data theft, ransomware deployment, or lateral movement within the network.
Likely Case
Local privilege escalation where an attacker with limited access gains administrative privileges, enabling further system exploitation and persistence.
If Mitigated
Limited impact if proper application sandboxing and least privilege principles are enforced, potentially containing the exploit to the user context.
🎯 Exploit Status
Proof of concept available in GitHub repository. Exploitation requires user to open a malicious TIF file, making social engineering likely. No authentication bypass needed beyond local file access.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Version 2.51.6 or later
Vendor Advisory: https://www.xnview.com/en/xnview/
Restart Required: No
Instructions:
1. Download latest version from xnview.com. 2. Install over existing installation. 3. Verify version is 2.51.6 or higher.
🔧 Temporary Workarounds
Disable TIF file association
windowsRemove XnView as default handler for TIF files to prevent automatic exploitation
Windows: Control Panel > Default Programs > Set Associations > Find .tif > Change to another program
Application sandboxing
allRun XnView in restricted environment to limit exploit impact
Windows: Use Windows Sandbox or AppLocker rules
Linux: Use firejail or SELinux/AppArmor policies
🧯 If You Can't Patch
- Implement strict file type validation and block suspicious TIF files at email gateways and file shares
- Apply least privilege principle: Run XnView with limited user account, not administrative privileges
🔍 How to Verify
Check if Vulnerable:
Check XnView version: Open XnView > Help > About. If version is exactly 2.51.5, system is vulnerable.Check Version:
Windows: xnview.exe --version (if supported) or check Help > About. Linux: ./xnview --version or check About dialog.Verify Fix Applied:
Verify version is 2.51.6 or higher in Help > About menu. Test with known safe TIF files to ensure functionality.📡 Detection & Monitoring
Log Indicators:
- Application crashes with TIF file processing
- Unusual process spawning from xnview.exe
- Memory access violation errors in application logs
Network Indicators:
- Unusual outbound connections following TIF file opening
- DNS requests to suspicious domains after file processing
SIEM Query:
Process:xnview.exe AND (EventID:1000 OR EventID:1001) AND FileExtension:.tif