CVE-2023-53891
📋 TL;DR
Blackcat CMS 1.4 contains a stored cross-site scripting vulnerability that allows authenticated users to inject malicious JavaScript into page content. When other users view compromised pages, the injected scripts execute in their browsers, potentially stealing session cookies or performing actions on their behalf. This affects all Blackcat CMS 1.4 installations with authenticated user accounts.
💻 Affected Systems
- Blackcat CMS
📦 What is this software?
Blackcat Cms by Blackcat Cms
⚠️ Risk & Real-World Impact
Worst Case
Attackers could steal administrator session cookies, take over admin accounts, deface websites, or redirect users to malicious sites, potentially leading to complete system compromise.
Likely Case
Authenticated attackers inject malicious scripts that execute when other users view pages, leading to session hijacking, credential theft, or unauthorized actions within the CMS.
If Mitigated
With proper input validation and output encoding, malicious scripts are neutralized before execution, preventing successful exploitation.
🎯 Exploit Status
Exploitation requires authenticated access. Public exploit code is available, making attacks easy for authenticated malicious users.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Not available
Vendor Advisory: https://blackcat-cms.org/
Restart Required: No
Instructions:
No official patch available. Consider upgrading to a newer version if available, implementing workarounds, or switching to alternative CMS platforms.
🔧 Temporary Workarounds
Implement Input Validation and Output Encoding
allAdd server-side validation to sanitize user input in page content fields and implement proper output encoding when displaying content.
Modify Blackcat CMS source code to add input sanitization functions for page content fields
Implement Content Security Policy (CSP)
allAdd CSP headers to restrict script execution sources and prevent inline script execution.
Add 'Content-Security-Policy: default-src 'self'; script-src 'self'' to HTTP headers
🧯 If You Can't Patch
- Restrict authenticated user permissions to minimize who can modify page content
- Implement web application firewall (WAF) rules to detect and block XSS payloads
🔍 How to Verify
Check if Vulnerable:
Test by attempting to inject a simple XSS payload like <script>alert('XSS')</script> in the page modification interface and check if it executes when viewing the page.Check Version:
Check Blackcat CMS version in admin panel or configuration filesVerify Fix Applied:
After implementing workarounds, test with the same XSS payload to confirm it no longer executes and appears as plain text.📡 Detection & Monitoring
Log Indicators:
- Unusual page modification activity, especially with script tags or JavaScript code in content fields
Network Indicators:
- HTTP requests containing suspicious script tags or JavaScript in POST data to page modification endpoints
SIEM Query:
source="web_logs" AND ("<script" OR "javascript:" OR "onerror=" OR "onload=") AND uri_path="/admin/pages/modify"