CVE-2020-22153
📋 TL;DR
CVE-2020-22153 is a critical file upload vulnerability in FUEL-CMS that allows remote attackers to upload malicious PHP files and execute arbitrary code on the server. This affects all systems running FUEL-CMS version 1.4.6 with the vulnerable navigation function exposed. Attackers can gain complete control over affected web servers.
💻 Affected Systems
- FUEL-CMS
📦 What is this software?
Fuel Cms by Thedaylightstudio
⚠️ Risk & Real-World Impact
Worst Case
Complete server compromise leading to data theft, ransomware deployment, lateral movement to internal networks, and persistent backdoor installation.
Likely Case
Webshell installation allowing file system access, credential harvesting, and further exploitation of the hosting environment.
If Mitigated
Limited impact with proper file upload restrictions, but still potentially dangerous if other security controls fail.
🎯 Exploit Status
Simple file upload exploitation with publicly available proof-of-concept code. Attackers can easily automate exploitation.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Version 1.4.7 and later
Vendor Advisory: https://github.com/daylightstudio/FUEL-CMS/issues/553
Restart Required: No
Instructions:
1. Backup your current installation. 2. Download FUEL-CMS 1.4.7 or later from the official repository. 3. Replace the vulnerable files with patched versions. 4. Verify the navigation.php file has proper file type validation.
🔧 Temporary Workarounds
File Upload Restriction via .htaccess
allBlock PHP file uploads at the web server level
Add to .htaccess: <FilesMatch "\.php$">
Order Allow,Deny
Deny from all
</FilesMatch>
Disable Navigation Function
allTemporarily disable the vulnerable navigation function if not needed
Comment out or remove navigation-related routes in application/config/routes.php
🧯 If You Can't Patch
- Implement strict file upload validation: only allow specific file types (images, documents) and validate file extensions and MIME types
- Deploy a Web Application Firewall (WAF) with rules to block PHP file uploads and monitor for exploitation attempts
🔍 How to Verify
Check if Vulnerable:
Check if running FUEL-CMS version 1.4.6 by examining the fuel/application/config/version.php file or using the admin interface version display.Check Version:
cat fuel/application/config/version.php | grep 'FUEL_VERSION'Verify Fix Applied:
After patching, attempt to upload a PHP file through the navigation function - it should be rejected with proper error messages.📡 Detection & Monitoring
Log Indicators:
- Multiple failed upload attempts with .php extensions
- Successful uploads of .php files to upload directories
- Unusual POST requests to navigation-related endpoints
Network Indicators:
- POST requests with file uploads containing PHP content
- Traffic to unexpected .php files in upload directories
SIEM Query:
source="web_logs" AND (uri="/fuel/navigation" OR uri CONTAINS "upload") AND (file_extension=".php" OR content_type="application/x-php")