CVE-2024-20320
📋 TL;DR
This vulnerability allows authenticated local attackers with low privileges on affected Cisco routers to elevate their privileges to root by exploiting insufficient argument validation in the SSH client CLI command. It affects Cisco IOS XR Software on 8000 Series, NCS 540 Series, and NCS 5700 Series routers. Attackers need existing access to the device's command-line interface.
💻 Affected Systems
- Cisco 8000 Series Routers
- Cisco Network Convergence System 540 Series Routers
- Cisco Network Convergence System 5700 Series Routers
📦 What is this software?
Ios Xr by Cisco
Ios Xr by Cisco
Ios Xr by Cisco
Ios Xr by Cisco
Ios Xr by Cisco
Ios Xr by Cisco
Ios Xr by Cisco
Ios Xr by Cisco
Ios Xr by Cisco
Ios Xr by Cisco
Ios Xr by Cisco
Ios Xr by Cisco
Ios Xr by Cisco
Ios Xr by Cisco
Ios Xr by Cisco
Ios Xr by Cisco
Ios Xr by Cisco
Ios Xr by Cisco
Ios Xr by Cisco
Ios Xr by Cisco
Ios Xr by Cisco
Ios Xr by Cisco
Ios Xr by Cisco
Ios Xr by Cisco
Ios Xr by Cisco
⚠️ Risk & Real-World Impact
Worst Case
Complete device compromise with root access, enabling configuration changes, data exfiltration, persistence establishment, and use as a pivot point in the network.
Likely Case
Privilege escalation from a low-privileged user to root, allowing unauthorized configuration changes and potential lateral movement within the network.
If Mitigated
Limited impact if proper access controls restrict low-privileged user access and command execution is monitored.
🎯 Exploit Status
Exploitation requires authenticated access and knowledge of the specific crafted SSH client command. No public exploit code is currently available.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Cisco IOS XR Software releases 7.11.2, 7.10.3, 7.9.4, 7.8.3, 7.7.2, 7.6.4, 7.5.3, 7.4.2, 7.3.4, and 7.2.3 or later
Vendor Advisory: https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-iosxr-ssh-privesc-eWDMKew3
Restart Required: Yes
Instructions:
1. Check current IOS XR version using 'show version'. 2. Download appropriate fixed release from Cisco Software Center. 3. Follow Cisco IOS XR Software upgrade procedures. 4. Reboot device after upgrade completion.
🔧 Temporary Workarounds
Restrict SSH client command access
allRemove or restrict execute permissions for the SSH client command from low-privileged users
configure terminal
username <username> privilege <level>
end
write memory
Disable SSH client feature
allDisable SSH client functionality if not required for operations
configure terminal
no ssh client enable
end
write memory
🧯 If You Can't Patch
- Implement strict role-based access control to limit low-privileged user access to CLI commands
- Monitor and audit SSH client command usage through syslog and implement alerting for suspicious patterns
🔍 How to Verify
Check if Vulnerable:
Run 'show version' and check if IOS XR version is prior to fixed releases listed in affected_systems.versionsCheck Version:
show version | include Cisco IOS XR SoftwareVerify Fix Applied:
After patching, run 'show version' to confirm version is at or above fixed releases, and test SSH client command with various arguments to ensure proper validation📡 Detection & Monitoring
Log Indicators:
- Unusual SSH client command usage patterns
- Multiple failed privilege escalation attempts
- SSH client commands with unusual arguments
Network Indicators:
- Unusual SSH connections originating from affected devices
- Changes in device configuration patterns
SIEM Query:
source="cisco_ios_xr" AND (command="ssh" OR command="ssh client") AND args CONTAINS suspicious_pattern