CVE-2020-22201
📋 TL;DR
CVE-2020-22201 is a remote code execution vulnerability in phpCMS 2008 sp4 that allows attackers to execute arbitrary PHP commands via the pagesize parameter in yp/product.php. This affects all systems running the vulnerable phpCMS version. Attackers can gain full control of affected web servers.
💻 Affected Systems
- phpCMS
📦 What is this software?
Phpcms by Phpcms
⚠️ Risk & Real-World Impact
Worst Case
Complete server compromise allowing attackers to execute arbitrary commands, steal data, install malware, pivot to internal networks, and maintain persistent access.
Likely Case
Web server takeover leading to website defacement, data theft, cryptocurrency mining, or use as part of a botnet.
If Mitigated
Limited impact if proper web application firewalls, input validation, and least privilege principles are implemented.
🎯 Exploit Status
Exploitation requires sending a crafted HTTP request with malicious PHP code in the pagesize parameter. Public proof-of-concept code exists.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: N/A
Vendor Advisory: N/A
Restart Required: No
Instructions:
1. Upgrade to a supported, modern CMS platform as phpCMS 2008 is outdated and no longer maintained. 2. If upgrade is impossible, apply input validation and sanitization to the pagesize parameter.
🔧 Temporary Workarounds
Input Validation Filter
allAdd input validation to reject or sanitize malicious pagesize parameter values
Modify yp/product.php to validate pagesize parameter contains only numeric values
Web Application Firewall Rule
allBlock requests containing PHP code patterns in the pagesize parameter
Add WAF rule to detect and block patterns like <?php, eval(), system(), exec() in URL parameters
🧯 If You Can't Patch
- Implement strict input validation on all user-supplied parameters
- Deploy a web application firewall with RCE protection rules
🔍 How to Verify
Check if Vulnerable:
Check if phpCMS version is 2008 sp4 by examining version files or configuration. Test by sending a request to yp/product.php with pagesize parameter containing test payload.Check Version:
Check phpCMS configuration files or admin panel for version informationVerify Fix Applied:
Test that malicious pagesize parameter values are rejected or sanitized. Verify no PHP code execution occurs.📡 Detection & Monitoring
Log Indicators:
- HTTP requests to yp/product.php with unusual pagesize parameter values
- Web server logs showing PHP execution errors
- System logs showing unexpected process execution
Network Indicators:
- HTTP POST/GET requests containing PHP code patterns in parameters
- Outbound connections from web server to suspicious IPs
SIEM Query:
source="web_logs" AND uri="*yp/product.php*" AND (param="*<?php*" OR param="*eval(*" OR param="*system(*")