CVE-2020-19891
📋 TL;DR
DBHcms v1.2.0 contains an arbitrary file write vulnerability in the editor module that allows authenticated admin users to write arbitrary content to any file on the server. This enables attackers to upload webshells and gain remote code execution. Only DBHcms v1.2.0 installations with admin user access are affected.
💻 Affected Systems
- DBHcms
📦 What is this software?
Dbhcms by Dbhcms Project
⚠️ Risk & Real-World Impact
Worst Case
Complete system compromise via webshell leading to data theft, ransomware deployment, or use as attack platform
Likely Case
Webshell installation leading to data exfiltration, defacement, or lateral movement within the network
If Mitigated
Limited impact due to proper access controls, file permissions, and monitoring
🎯 Exploit Status
Exploitation requires admin credentials; public proof-of-concept exists in GitHub repositories
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Unknown
Vendor Advisory: None known
Restart Required: No
Instructions:
No official patch available. Upgrade to newer version if exists, or implement workarounds.
🔧 Temporary Workarounds
Input Validation for Editor Module
allAdd file extension validation and path sanitization to mod.editor.php
Edit dbhcms\mod\mod.editor.php to validate $_POST['updatefile'] against allowed file extensions and paths
File Permission Restrictions
linuxSet strict file permissions on web directories to prevent PHP file execution
chmod 644 *.php
chmod 755 uploads/
chmod 000 dangerous_directories/
🧯 If You Can't Patch
- Implement strict access controls and multi-factor authentication for admin accounts
- Deploy web application firewall (WAF) rules to block file write attempts to unauthorized locations
🔍 How to Verify
Check if Vulnerable:
Check if running DBHcms v1.2.0 and examine dbhcms\mod\mod.editor.php for lack of input validation on $_POST['updatefile']Check Version:
Check DBHcms configuration files or admin panel for version informationVerify Fix Applied:
Test if arbitrary file writes are prevented by attempting to write to unauthorized locations via editor module📡 Detection & Monitoring
Log Indicators:
- Unusual file write operations in web server logs
- POST requests to mod.editor.php with suspicious filenames
- Creation of unexpected PHP files in web directories
Network Indicators:
- HTTP POST requests containing file write patterns to editor endpoint
- Unusual outbound connections from web server
SIEM Query:
source="web_logs" AND uri="/dbhcms/mod/editor.php" AND method="POST" AND (filename="*.php" OR filename="*.exe" OR filename="*.sh")