CVE-2023-53925
📋 TL;DR
UliCMS 2023.1 contains a stored cross-site scripting vulnerability where attackers can upload malicious SVG files containing JavaScript through the file management interface. When other users view these SVG files, the embedded scripts execute in their browsers, potentially stealing session cookies or performing actions on their behalf. All users running UliCMS 2023.1 are affected.
💻 Affected Systems
- UliCMS
📦 What is this software?
Ulicms by Ulicms
⚠️ Risk & Real-World Impact
Worst Case
Attackers could steal administrator session cookies, gain administrative access, deface websites, or install backdoors for persistent access.
Likely Case
Attackers steal user session cookies to hijack accounts, perform unauthorized actions, or redirect users to malicious sites.
If Mitigated
With proper input validation and file type restrictions, the attack surface is minimized, though some risk remains if SVG viewing is allowed.
🎯 Exploit Status
Exploitation requires authenticated access to upload files, but the attack is straightforward once access is obtained.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: 2023.2 or later
Vendor Advisory: https://en.ulicms.de/
Restart Required: No
Instructions:
1. Backup your UliCMS installation and database. 2. Download the latest version from the official UliCMS website. 3. Replace the existing files with the updated version. 4. Verify that the update was successful by checking the version in the admin panel.
🔧 Temporary Workarounds
Disable SVG file uploads
allModify UliCMS configuration to block SVG file uploads through the file management interface.
Edit the file upload configuration in UliCMS to remove 'svg' from allowed file types.
Implement Content Security Policy (CSP)
allAdd a CSP header to prevent inline script execution in SVG files.
Add 'Content-Security-Policy: script-src 'self'' to your web server configuration.
🧯 If You Can't Patch
- Restrict file upload permissions to trusted users only.
- Implement web application firewall (WAF) rules to block malicious SVG uploads.
🔍 How to Verify
Check if Vulnerable:
Check if your UliCMS version is 2023.1 by logging into the admin panel and viewing the version information.Check Version:
Check the UliCMS admin dashboard or view the version in the system settings.Verify Fix Applied:
After updating, confirm the version is 2023.2 or later in the admin panel and test SVG upload functionality to ensure scripts are not executed.📡 Detection & Monitoring
Log Indicators:
- Unusual SVG file uploads from user accounts
- Multiple failed upload attempts with SVG files
Network Indicators:
- HTTP POST requests to file upload endpoints with SVG content
- Unexpected JavaScript in SVG file responses
SIEM Query:
source="web_server" AND (uri_path="/admin/?action=files_upload" OR file_extension="svg")