CVE-2023-31689
📋 TL;DR
This vulnerability in Wcms 0.3.2 allows unauthenticated attackers to upload arbitrary files and execute malicious code through crafted requests to the /wcms/wex/html.php endpoint. Attackers can achieve remote command execution by exploiting improper input validation in the finish and textAreaCode parameters. Anyone running Wcms 0.3.2 with the vulnerable component accessible is affected.
💻 Affected Systems
- Wcms
📦 What is this software?
Wcms by Wcms
⚠️ Risk & Real-World Impact
Worst Case
Complete system compromise allowing attackers to execute arbitrary commands, steal data, install persistent backdoors, and pivot to other systems in the network.
Likely Case
Remote code execution leading to web server compromise, data exfiltration, and potential lateral movement within the network.
If Mitigated
Limited impact if proper network segmentation, web application firewalls, and file upload restrictions are in place.
🎯 Exploit Status
The vulnerability requires no authentication and has publicly available proof-of-concept code, making exploitation trivial for attackers.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Not available
Vendor Advisory: https://github.com/vedees/wcms/issues/15
Restart Required: No
Instructions:
No official patch is available. Consider upgrading to a newer version if available, or implement workarounds and mitigations.
🔧 Temporary Workarounds
Block vulnerable endpoint
allRestrict access to the /wcms/wex/html.php endpoint using web server configuration or firewall rules.
# Apache: RewriteRule ^/wcms/wex/html\.php$ - [F]
# Nginx: location ~ ^/wcms/wex/html\.php$ { deny all; }
Implement file upload restrictions
allConfigure web application firewall or server to block file uploads with dangerous extensions and validate all uploads.
# Example mod_security rule: SecRule FILES_TMPNAMES "@rx \.(php|phtml|phar|inc)$" "deny,status:403"
🧯 If You Can't Patch
- Isolate the Wcms instance in a segmented network zone with strict outbound firewall rules
- Implement comprehensive monitoring and alerting for suspicious file uploads and command execution attempts
🔍 How to Verify
Check if Vulnerable:
Check if Wcms version is 0.3.2 and if /wcms/wex/html.php endpoint is accessible. Test with a harmless payload to confirm vulnerability.Check Version:
Check Wcms configuration files or admin panel for version informationVerify Fix Applied:
Verify that the vulnerable endpoint is no longer accessible or that file upload restrictions are properly enforced.📡 Detection & Monitoring
Log Indicators:
- Unusual POST requests to /wcms/wex/html.php with finish and textAreaCode parameters
- File uploads with suspicious extensions to Wcms directories
- System command execution from web server process
Network Indicators:
- Outbound connections from web server to suspicious IPs or command-and-control servers
- Unusual traffic patterns from Wcms instance
SIEM Query:
source="web_server_logs" AND (uri="/wcms/wex/html.php" AND (param="finish" OR param="textAreaCode"))