CVE-2023-39377
📋 TL;DR
This vulnerability in SiberianCMS allows administrators to upload dangerous file types without proper validation. Attackers with admin access could upload malicious files like PHP scripts or executables, potentially leading to server compromise. Only systems with SiberianCMS installed and users with administrative privileges are affected.
💻 Affected Systems
- SiberianCMS
📦 What is this software?
Siberiancms by Siberiancms
Siberiancms by Siberiancms
⚠️ Risk & Real-World Impact
Worst Case
Full server compromise through remote code execution, data theft, or complete system takeover via uploaded malicious files.
Likely Case
Attackers upload web shells or backdoors to gain persistent access, steal data, or pivot to other systems.
If Mitigated
Limited impact with proper file upload restrictions and admin account security, though risk remains if admin credentials are compromised.
🎯 Exploit Status
Exploitation requires admin credentials; unspecified method suggests limited public details.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Unknown from provided references; check vendor advisory for specific version.
Vendor Advisory: https://www.gov.il/en/Departments/faq/cve_advisories
Restart Required: No
Instructions:
1. Check the vendor advisory for patch details. 2. Update SiberianCMS to the latest patched version. 3. Verify file upload restrictions are enforced.
🔧 Temporary Workarounds
Restrict File Upload Types
allConfigure web server or application to block dangerous file extensions like .php, .exe, .sh.
# Example for Apache: Add to .htaccess
<FilesMatch "\.(php|exe|sh)$">
Order Allow,Deny
Deny from all
</FilesMatch>
Harden Admin Accounts
allEnforce strong passwords, multi-factor authentication, and limit admin access to trusted IPs.
# Example IP restriction for Apache
<Location "/admin">
Order Deny,Allow
Deny from all
Allow from 192.168.1.0/24
</Location>
🧯 If You Can't Patch
- Implement strict file upload validation server-side to block dangerous file types.
- Monitor admin account activity and file upload logs for suspicious behavior.
🔍 How to Verify
Check if Vulnerable:
Review SiberianCMS version and check if file upload functionality lacks validation for dangerous types; test with admin account if safe.Check Version:
# Check SiberianCMS version via its admin panel or configuration files; specific command varies by installation.Verify Fix Applied:
After patching, attempt to upload a dangerous file type (e.g., .php) as admin; it should be blocked or rejected.📡 Detection & Monitoring
Log Indicators:
- Admin login from unusual IPs
- File uploads with dangerous extensions (e.g., .php, .exe)
- Large or unusual file uploads in web server logs
Network Indicators:
- Unusual outbound connections from web server post-upload
- HTTP requests to uploaded malicious files
SIEM Query:
Example: 'source="web.log" AND (extension=".php" OR extension=".exe") AND action="upload"'