CVE-2020-20698
📋 TL;DR
This vulnerability allows remote attackers to execute arbitrary code on S-CMS PHP v3.0 systems by modifying PHP files through the /1.com.php endpoint. It affects all deployments of S-CMS PHP v3.0 that have this vulnerable component accessible. Attackers can gain complete control of affected web servers.
💻 Affected Systems
- S-CMS PHP
📦 What is this software?
S Cms by S Cms
⚠️ Risk & Real-World Impact
Worst Case
Complete server compromise allowing data theft, malware deployment, lateral movement to internal networks, and persistent backdoor installation.
Likely Case
Webshell installation leading to website defacement, data exfiltration, and use as attack platform for further exploitation.
If Mitigated
Limited impact with proper network segmentation, web application firewalls, and file integrity monitoring in place.
🎯 Exploit Status
Exploit requires simple HTTP POST request to vulnerable endpoint. No authentication or special privileges needed.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Unknown
Vendor Advisory: No official vendor advisory found
Restart Required: No
Instructions:
1. Upgrade to a newer version of S-CMS PHP if available. 2. If no newer version exists, remove or rename the /1.com.php file. 3. Consider migrating to alternative CMS software.
🔧 Temporary Workarounds
Remove vulnerable file
linuxDelete or rename the vulnerable /1.com.php file to prevent exploitation
rm /path/to/webroot/1.com.php
mv /path/to/webroot/1.com.php /path/to/webroot/1.com.php.disabled
Restrict file permissions
linuxSet restrictive permissions on PHP files to prevent modification
chmod 644 /path/to/webroot/*.php
chown www-data:www-data /path/to/webroot/*.php
🧯 If You Can't Patch
- Implement web application firewall (WAF) rules to block requests to /1.com.php
- Enable file integrity monitoring to detect unauthorized PHP file modifications
🔍 How to Verify
Check if Vulnerable:
Check if file exists: ls -la /path/to/webroot/1.com.php. If file exists and contains vulnerable code, system is vulnerable.Check Version:
Check S-CMS version in configuration files or admin panel. Look for version 3.0 indicators.Verify Fix Applied:
Verify file no longer exists or has been renamed: ls -la /path/to/webroot/1.com.php*. File should not be accessible via HTTP.📡 Detection & Monitoring
Log Indicators:
- HTTP POST requests to /1.com.php
- Unusual file modifications to PHP files
- Webshell creation in web directories
Network Indicators:
- HTTP traffic to /1.com.php endpoint
- Unusual outbound connections from web server
SIEM Query:
source="web_logs" AND (uri="/1.com.php" OR uri="*1.com.php*")