CVE-2020-3420
📋 TL;DR
This cross-site scripting (XSS) vulnerability in Cisco Unified Communications Manager allows authenticated attackers to inject malicious scripts into the web management interface. When exploited, it enables attackers to execute arbitrary JavaScript in victims' browsers, potentially stealing session cookies or performing actions as authenticated users. Only authenticated users can exploit this vulnerability.
💻 Affected Systems
- Cisco Unified Communications Manager
- Cisco Unified Communications Manager Session Management Edition
📦 What is this software?
⚠️ Manual Verification Required
This CVE does not have specific version information in our database, so automatic vulnerability detection cannot determine if your system is affected.
Why? The CVE database entry doesn't specify which versions are vulnerable (no version ranges provided by the vendor/NVD).
🔒 Custom verification scripts are available for registered users. Sign up free to download automated test scripts.
- Review the CVE details at NVD
- Check vendor security advisories for your specific version
- Test if the vulnerability is exploitable in your environment
- Consider updating to the latest version as a precaution
⚠️ Risk & Real-World Impact
Worst Case
Attacker steals administrator session cookies, gains full administrative access to the Unified CM system, and potentially compromises the entire telephony infrastructure.
Likely Case
Attacker steals session cookies of regular users, gains unauthorized access to their accounts, and performs limited administrative actions based on stolen privileges.
If Mitigated
With proper input validation and output encoding, the attack fails to execute malicious scripts, preventing any browser-based compromise.
🎯 Exploit Status
Exploitation requires authenticated access and knowledge of the vulnerable input field. XSS attacks are generally straightforward to execute once the vulnerable parameter is identified.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: 12.5(1)SU6 and later
Vendor Advisory: https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-cucm-xss-bLZw4Ctq
Restart Required: Yes
Instructions:
1. Download the appropriate patch from Cisco's software download center. 2. Backup current configuration. 3. Apply the patch following Cisco's upgrade procedures. 4. Restart the Unified CM services or server as required.
🔧 Temporary Workarounds
No official workarounds
allCisco states there are no workarounds that address this vulnerability. Patching is the only solution.
🧯 If You Can't Patch
- Restrict access to the web management interface to only trusted networks and users
- Implement web application firewall (WAF) rules to detect and block XSS payloads
🔍 How to Verify
Check if Vulnerable:
Check the Unified CM version via the web interface (System > Cisco Unified CM Administration > Version) or CLI command 'show version active'Check Version:
show version activeVerify Fix Applied:
Verify the version is 12.5(1)SU6 or later and test the previously vulnerable input field with XSS payloads📡 Detection & Monitoring
Log Indicators:
- Unusual POST requests to management interface with script tags or JavaScript payloads
- Multiple failed login attempts followed by successful login and XSS payload submission
Network Indicators:
- HTTP requests containing <script> tags or JavaScript functions in parameter values
- Unusual outbound connections from management interface to external domains
SIEM Query:
source="unified_cm_logs" AND (http_method="POST" AND (uri_path="*admin*" OR uri_path="*management*") AND (http_query="*<script>*" OR http_query="*javascript:*" OR http_query="*onerror=*"))