CVE-2024-20252
📋 TL;DR
Multiple CSRF vulnerabilities in Cisco Expressway Series and TelePresence VCS allow unauthenticated remote attackers to trick authenticated users into performing arbitrary actions on affected devices. This affects Cisco Expressway-C, Expressway-E, and TelePresence VCS devices. Attackers can exploit these vulnerabilities to modify configurations, disrupt services, or potentially gain unauthorized access.
💻 Affected Systems
- Cisco Expressway Control (Expressway-C)
- Cisco Expressway Edge (Expressway-E)
- Cisco TelePresence Video Communication Server (VCS)
📦 What is this software?
⚠️ Risk & Real-World Impact
Worst Case
Complete compromise of device configuration leading to service disruption, data exfiltration, or use as pivot point into internal networks
Likely Case
Unauthorized configuration changes causing service disruption or security policy bypass
If Mitigated
Limited impact due to CSRF protections, network segmentation, or restricted admin access
🎯 Exploit Status
CSRF attacks require tricking authenticated admin users into visiting malicious pages; no authentication required for initial attack vector
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Refer to Cisco advisory for specific fixed versions
Vendor Advisory: https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-expressway-csrf-KnnZDMj3
Restart Required: Yes
Instructions:
1. Review Cisco advisory for affected versions 2. Download and apply appropriate firmware updates 3. Restart affected devices 4. Verify successful update
🔧 Temporary Workarounds
Implement CSRF Tokens
allAdd anti-CSRF tokens to web interface forms
Restrict Admin Access
allLimit administrative access to trusted networks and users
🧯 If You Can't Patch
- Implement network segmentation to isolate Expressway devices
- Require multi-factor authentication for administrative access
🔍 How to Verify
Check if Vulnerable:
Check device version against Cisco advisory; versions prior to fixed releases are vulnerableCheck Version:
ssh admin@expressway 'xstatus SystemUnit Software Version'Verify Fix Applied:
Verify device firmware version matches or exceeds fixed version listed in Cisco advisory📡 Detection & Monitoring
Log Indicators:
- Unexpected configuration changes
- Multiple failed login attempts followed by successful admin actions
- Admin sessions from unusual IP addresses
Network Indicators:
- HTTP POST requests to admin endpoints from non-admin networks
- Suspicious referrer headers in web traffic
SIEM Query:
source="expressway" AND (event_type="config_change" OR user="admin") AND src_ip NOT IN trusted_networks