CVE-2024-20511
📋 TL;DR
An unauthenticated cross-site scripting (XSS) vulnerability in Cisco Unified Communications Manager web interface allows attackers to execute malicious scripts in users' browsers by tricking them into clicking crafted links. This affects administrators and users of the web management interface. Attackers could steal session cookies, redirect users, or perform actions on their behalf.
💻 Affected Systems
- Cisco Unified Communications Manager
- Cisco Unified Communications Manager Session Management Edition
📦 What is this software?
⚠️ Risk & Real-World Impact
Worst Case
Attacker gains administrative access to Unified CM, modifies configurations, intercepts communications, or deploys additional malware across the organization's voice infrastructure.
Likely Case
Attacker steals session cookies or credentials from authenticated users, leading to unauthorized access to the management interface and potential configuration changes.
If Mitigated
With proper input validation and output encoding, the attack fails to execute malicious scripts, limiting impact to failed exploitation attempts.
🎯 Exploit Status
Exploitation requires social engineering to trick users into clicking malicious links. No authentication required for initial attack vector.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: 15.0(1)SU1 and later
Vendor Advisory: https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-cucm-xss-SVCkMMW
Restart Required: Yes
Instructions:
1. Download patch from Cisco Software Center. 2. Backup current configuration. 3. Apply patch following Cisco upgrade procedures. 4. Restart affected services. 5. Verify patch installation.
🔧 Temporary Workarounds
Input Validation Enhancement
allImplement additional input validation and output encoding for web interface parameters
Content Security Policy
allImplement strict Content Security Policy headers to restrict script execution
🧯 If You Can't Patch
- Restrict access to Unified CM web interface to trusted networks only using firewall rules
- Implement web application firewall (WAF) with XSS protection rules
- Educate users about phishing risks and suspicious links
🔍 How to Verify
Check if Vulnerable:
Check Unified CM version via web interface: Admin > System > Software Versions, or CLI: show version activeCheck Version:
show version activeVerify Fix Applied:
Verify version is 15.0(1)SU1 or later and test XSS payloads in affected parameters📡 Detection & Monitoring
Log Indicators:
- Unusual parameter values in web access logs containing script tags
- Multiple failed login attempts following suspicious URL access
Network Indicators:
- HTTP requests with encoded script payloads in parameters
- Unusual outbound connections from Unified CM server
SIEM Query:
source="unified_cm" AND (url="*<script>*" OR url="*javascript:*" OR param="*alert(*")