CVE-2020-21651
📋 TL;DR
CVE-2020-21651 is a critical remote code execution vulnerability in Myucms v2.2.1 that allows attackers to execute arbitrary code on affected systems via the add() method in controller/point.php. This affects all users running the vulnerable version of Myucms content management system. Successful exploitation gives attackers full control over the compromised server.
💻 Affected Systems
- Myucms
📦 What is this software?
Myucms by Myucms Project
⚠️ Risk & Real-World Impact
Worst Case
Complete system compromise allowing attackers to execute arbitrary commands, steal sensitive data, install malware, pivot to other systems, and maintain persistent access.
Likely Case
Attackers gain shell access to the web server, deface websites, install cryptocurrency miners or ransomware, and exfiltrate database contents.
If Mitigated
Limited impact with proper network segmentation, web application firewalls, and least privilege configurations preventing lateral movement.
🎯 Exploit Status
Public GitHub issues demonstrate the vulnerability, and RCE vulnerabilities in CMS systems are frequently weaponized. The exploit appears straightforward based on available information.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Unknown
Vendor Advisory: No official vendor advisory found
Restart Required: No
Instructions:
1. Check for official patches from Myucms developers. 2. If no patch exists, upgrade to a newer version if available. 3. Consider migrating to alternative CMS solutions if Myucms is no longer maintained.
🔧 Temporary Workarounds
Disable vulnerable endpoint
linuxRemove or restrict access to controller/point.php to prevent exploitation
mv /path/to/myucms/controller/point.php /path/to/myucms/controller/point.php.disabled
Implement WAF rules
allConfigure web application firewall to block requests to the vulnerable endpoint
🧯 If You Can't Patch
- Isolate the affected system in a DMZ with strict network controls
- Implement application allowlisting and disable unnecessary PHP functions
🔍 How to Verify
Check if Vulnerable:
Check if Myucms version is 2.2.1 by examining version files or configuration. Review if controller/point.php exists with the add() method.Check Version:
grep -r 'version' /path/to/myucms/ | grep -i '2.2.1'Verify Fix Applied:
Verify controller/point.php is removed, renamed, or patched. Test with controlled payloads to confirm RCE is no longer possible.📡 Detection & Monitoring
Log Indicators:
- Unusual POST requests to controller/point.php
- System commands execution in web logs
- Unexpected process spawns from web server user
Network Indicators:
- Outbound connections from web server to suspicious IPs
- Unusual traffic patterns from web application
SIEM Query:
source="web_logs" AND (uri="*controller/point.php*" OR method="POST" AND uri="*point.php*")