CVE-2023-31505
📋 TL;DR
This vulnerability allows authenticated attackers to upload malicious .phtml files to Schlix CMS, leading to remote code execution and potential data theft. It affects Schlix CMS v2.2.8-1 installations with authenticated user access. Attackers can gain full control of affected systems.
💻 Affected Systems
- Schlix CMS
📦 What is this software?
Cms by Schlix
⚠️ Risk & Real-World Impact
Worst Case
Complete system compromise, data exfiltration, lateral movement, and persistent backdoor installation.
Likely Case
Webshell deployment leading to data theft, defacement, and further exploitation of the server.
If Mitigated
Limited impact with proper file upload restrictions and web server configuration.
🎯 Exploit Status
Exploitation requires authenticated access; public proof-of-concept demonstrates file upload leading to RCE.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Unknown
Vendor Advisory: Not available
Restart Required: No
Instructions:
No official patch available. Consider upgrading to a newer version if available or implementing workarounds.
🔧 Temporary Workarounds
Restrict File Upload Extensions
allConfigure web server to block .phtml file uploads and execution.
# In Apache .htaccess:
<FilesMatch "\.phtml$">
Order Allow,Deny
Deny from all
</FilesMatch>
# In Nginx config:
location ~ \.phtml$ {
deny all;
}
Disable PHP Execution in Upload Directory
allPrevent PHP execution in directories where files are uploaded.
# In Apache .htaccess in upload directory:
php_flag engine off
# In Nginx config for upload location:
location /uploads/ {
location ~ \.php$ {
deny all;
}
}
🧯 If You Can't Patch
- Implement strict file upload validation to only allow safe extensions (e.g., .jpg, .png).
- Restrict authenticated user permissions and implement least privilege access controls.
🔍 How to Verify
Check if Vulnerable:
Check if running Schlix CMS v2.2.8-1 and test authenticated file upload of .phtml files.Check Version:
Check CMS admin panel or version files in installation directory.Verify Fix Applied:
Verify .phtml files cannot be uploaded or executed; test with safe file types only.📡 Detection & Monitoring
Log Indicators:
- File upload attempts with .phtml extension
- Unauthorized file execution in upload directories
- Webshell access patterns
Network Indicators:
- Unexpected outbound connections from web server
- Suspicious POST requests to upload endpoints
SIEM Query:
source="web_logs" AND (uri_path="/upload" OR file_extension=".phtml")