CVE-2020-3177
📋 TL;DR
CVE-2020-3177 is a directory traversal vulnerability in Cisco Unified Communications Manager's TAPS interface that allows unauthenticated remote attackers to read arbitrary files on affected systems. This affects Cisco UCM and SME deployments with TAPS enabled. Attackers can exploit this by sending specially crafted requests to the vulnerable interface.
💻 Affected Systems
- Cisco Unified Communications Manager
- Cisco Unified Communications Manager Session Management Edition
📦 What is this software?
⚠️ Risk & Real-World Impact
Worst Case
Complete system compromise through reading sensitive configuration files, passwords, certificates, or other critical system files leading to further attacks.
Likely Case
Information disclosure of sensitive configuration data, user credentials, or system files that could enable lateral movement or additional attacks.
If Mitigated
Limited impact if proper network segmentation and access controls prevent external access to the TAPS interface.
🎯 Exploit Status
Exploitation requires network access to the TAPS interface (port 6970 by default).
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: 12.5(1)SU4 and later
Vendor Advisory: https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-cucm-taps-path-trav-pfsFO93r
Restart Required: Yes
Instructions:
1. Upgrade to Cisco Unified Communications Manager version 12.5(1)SU4 or later. 2. Apply the patch through Cisco's standard update process. 3. Restart affected services or the entire system as required.
🔧 Temporary Workarounds
Disable TAPS Interface
allDisable the TAPS service if not required for your deployment
Navigate to Cisco Unified CM Administration > System > Service Parameters > Select server > Cisco TAPS Service > Set 'Cisco TAPS Service Activation' to 'False'
Restrict Network Access
linuxBlock external access to TAPS port (default 6970) using firewall rules
iptables -A INPUT -p tcp --dport 6970 -j DROP
firewall-cmd --permanent --add-rich-rule='rule family="ipv4" source address="0.0.0.0/0" port port="6970" protocol="tcp" reject'
🧯 If You Can't Patch
- Implement strict network segmentation to isolate affected systems from untrusted networks
- Deploy web application firewall (WAF) rules to detect and block directory traversal attempts
🔍 How to Verify
Check if Vulnerable:
Check Cisco Unified Communications Manager version via CLI: 'show version active' or web interface: System > Cisco Unified OS Administration > Show > Software VersionsCheck Version:
show version activeVerify Fix Applied:
Verify version is 12.5(1)SU4 or later and test TAPS interface with directory traversal attempts📡 Detection & Monitoring
Log Indicators:
- Unusual TAPS service requests with '../' patterns
- Failed file access attempts in system logs
- Multiple requests to TAPS from single IP
Network Indicators:
- HTTP requests to /taps/ with directory traversal patterns
- Unusual traffic on port 6970
SIEM Query:
source="*cucm*" AND ("../" OR "..\" OR "%2e%2e%2f") AND ("taps" OR port=6970)