CVE-2022-23906
📋 TL;DR
CMS Made Simple v2.2.15 contains a remote command execution vulnerability in the upload avatar function. Attackers can execute arbitrary commands on the server by uploading a specially crafted image file. All systems running the vulnerable version are affected.
💻 Affected Systems
- CMS Made Simple
📦 What is this software?
Cms Made Simple by Cmsmadesimple
⚠️ Risk & Real-World Impact
Worst Case
Full server compromise allowing attackers to execute arbitrary commands, install malware, steal data, or pivot to other systems.
Likely Case
Webshell deployment leading to data theft, defacement, or use as a foothold for further attacks.
If Mitigated
Limited impact if proper file upload restrictions and web application firewalls are in place.
🎯 Exploit Status
Exploitation requires user authentication to access avatar upload functionality.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: v2.2.16
Vendor Advisory: http://dev.cmsmadesimple.org/bug/view/12502
Restart Required: No
Instructions:
1. Backup your CMS Made Simple installation and database. 2. Download v2.2.16 from the official website. 3. Replace all files with the new version. 4. Clear cache and verify functionality.
🔧 Temporary Workarounds
Disable Avatar Uploads
allTemporarily disable the avatar upload functionality in CMS Made Simple settings.
Restrict File Upload Types
linuxConfigure web server to block uploads of image files with embedded malicious content.
# Apache: Add to .htaccess
<FilesMatch "\.(php|phtml|php3|php4|php5|phps|php7|php8|inc|pl|py|jsp|asp|htm|html|shtml|sh|cgi)">
Order Allow,Deny
Deny from all
</FilesMatch>
🧯 If You Can't Patch
- Implement strict file upload validation and sanitization at the application level.
- Deploy a web application firewall (WAF) with RCE protection rules.
🔍 How to Verify
Check if Vulnerable:
Check CMS version in admin panel or by examining version.php file in installation directory.Check Version:
grep -r "CMS_VERSION" /path/to/cms/version.phpVerify Fix Applied:
Verify version is v2.2.16 or later and test avatar upload functionality with safe test files.📡 Detection & Monitoring
Log Indicators:
- Unusual file uploads to avatar directory
- Suspicious POST requests to upload endpoints
- Execution of system commands in web logs
Network Indicators:
- HTTP POST requests with image files containing embedded code
- Outbound connections from web server to suspicious IPs
SIEM Query:
source="web_logs" AND (uri_path="*upload*avatar*" OR method="POST") AND (file_extension="php" OR file_extension="phtml" OR file_extension="jsp")