CVE-2024-20253
📋 TL;DR
This critical vulnerability in Cisco Unified Communications and Contact Center Solutions allows unauthenticated remote attackers to execute arbitrary code on affected devices by sending crafted messages to listening ports. Successful exploitation grants attacker access to the underlying operating system with web services user privileges, potentially leading to full system compromise. Organizations using affected Cisco UC/CC products are at risk.
💻 Affected Systems
- Cisco Unified Communications Manager
- Cisco Unified Communications Manager Session Management Edition
- Cisco Unified Communications Manager IM & Presence Service
- Cisco Unified Contact Center Express
- Cisco Unified Contact Center Enterprise
📦 What is this software?
Unified Communications Manager Im And Presence Service by Cisco
View all CVEs affecting Unified Communications Manager Im And Presence Service →
⚠️ Risk & Real-World Impact
Worst Case
Complete system takeover with root access, data exfiltration, lateral movement within network, and persistent backdoor installation.
Likely Case
Remote code execution leading to service disruption, credential theft, and installation of malware or crypto-miners.
If Mitigated
Limited impact due to network segmentation, strict firewall rules, and immediate patching preventing successful exploitation.
🎯 Exploit Status
Unpatched internet-facing systems are highly vulnerable due to unauthenticated remote exploitation.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Multiple fixed versions available - refer to Cisco advisory for specific product/version mappings
Vendor Advisory: https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-cucm-rce-bWNzQcUm
Restart Required: Yes
Instructions:
1. Review Cisco advisory for affected versions. 2. Download appropriate patches from Cisco Software Center. 3. Apply patches following Cisco upgrade procedures. 4. Restart affected services/systems.
🔧 Temporary Workarounds
Network Access Control
allRestrict access to affected ports using firewall rules to only trusted IP addresses/networks.
Disable Unnecessary Services
linuxDisable web services if not required for business operations.
🧯 If You Can't Patch
- Implement strict network segmentation and firewall rules to isolate affected systems
- Deploy intrusion prevention systems with signatures for this vulnerability
🔍 How to Verify
Check if Vulnerable:
Check system version against affected versions in Cisco advisory and verify web services are enabled.Check Version:
show version active (Cisco CLI) or check via web interfaceVerify Fix Applied:
Verify system version is updated to patched version listed in Cisco advisory and test functionality.📡 Detection & Monitoring
Log Indicators:
- Unusual connection attempts to web service ports
- Unexpected process execution
- Authentication failures followed by successful connections
Network Indicators:
- Crafted packets to listening ports (typically TCP 80/443/5060/5061)
- Unusual outbound connections from affected systems
SIEM Query:
source_ip IN (affected_systems) AND (destination_port IN (80,443,5060,5061) AND payload_size > threshold)