CVE-2018-16286
📋 TL;DR
This vulnerability allows attackers to bypass authentication in LG SuperSign CMS by sending a 'captcha:pass' cookie and brute-forcing a 4-digit PIN. It affects organizations using LG SuperSign CMS for digital signage management.
💻 Affected Systems
- LG SuperSign CMS
📦 What is this software?
⚠️ Risk & Real-World Impact
Worst Case
Complete compromise of the SuperSign CMS, allowing unauthorized access to administrative functions, potential manipulation of digital signage content, and lateral movement to connected systems.
Likely Case
Unauthorized administrative access to the CMS, enabling attackers to modify digital signage content, potentially displaying malicious messages or disrupting operations.
If Mitigated
Limited impact if proper network segmentation and access controls prevent external access to the CMS interface.
🎯 Exploit Status
Exploitation requires sending a specific cookie and brute-forcing a 4-digit PIN (10,000 possibilities).
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Unknown specific version - check with LG for latest patched release
Vendor Advisory: No public vendor advisory found
Restart Required: Yes
Instructions:
1. Contact LG for latest patched version of SuperSign CMS. 2. Backup current configuration. 3. Install updated version. 4. Restart CMS services. 5. Verify authentication works correctly.
🔧 Temporary Workarounds
Network Access Restriction
allRestrict network access to SuperSign CMS to trusted IP addresses only
Use firewall rules to allow only specific IPs to access CMS port (typically 80/443)
Cookie Filtering
allBlock or filter 'captcha:pass' cookies at network perimeter
Configure WAF or proxy to strip 'captcha:pass' cookies from requests
🧯 If You Can't Patch
- Implement strict network segmentation to isolate SuperSign CMS from untrusted networks
- Enable detailed logging and monitoring for authentication attempts and cookie manipulation
🔍 How to Verify
Check if Vulnerable:
Attempt to access CMS login page with 'captcha:pass' cookie set and observe if CAPTCHA is bypassedCheck Version:
Check CMS version in web interface or configuration files (specific command varies by installation)Verify Fix Applied:
Verify that CAPTCHA is required regardless of cookies and PIN complexity is improved📡 Detection & Monitoring
Log Indicators:
- Multiple failed login attempts with 'captcha:pass' cookie present
- Successful logins without CAPTCHA completion
Network Indicators:
- HTTP requests containing 'captcha:pass' cookie to CMS endpoints
- Rapid PIN brute-force attempts
SIEM Query:
source="web_logs" AND (cookie="*captcha:pass*" OR uri="/login*") AND (status=200 OR status=302)