CVE-2021-1419
📋 TL;DR
This vulnerability in Cisco Access Points allows authenticated local users to modify files and potentially gain root privileges through improper file operation checks in the SSH management interface. It affects network administrators who can access affected devices via SSH. Successful exploitation could lead to complete device compromise.
💻 Affected Systems
- Cisco Aironet Access Points
- Cisco Catalyst 9100 Access Points
📦 What is this software?
⚠️ Risk & Real-World Impact
Worst Case
Attacker gains root privileges, completely compromises the device, and potentially pivots to other network resources.
Likely Case
Malicious insider or compromised admin account escalates privileges to root and modifies device configurations or installs persistent backdoors.
If Mitigated
With proper access controls and monitoring, exploitation is detected and contained before significant damage occurs.
🎯 Exploit Status
Requires authenticated SSH access. Exploitation involves making configuration changes through the SSH interface.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Varies by product - see Cisco advisory for specific fixed versions
Vendor Advisory: https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-cisco-ap-LLjsGxv
Restart Required: Yes
Instructions:
1. Check Cisco advisory for affected products and versions. 2. Download appropriate firmware updates from Cisco. 3. Apply updates following Cisco's upgrade procedures. 4. Reboot affected devices.
🔧 Temporary Workarounds
Restrict SSH Access
allLimit SSH access to trusted management networks and specific administrative hosts only
configure terminal
access-list 10 permit 192.168.1.0 0.0.0.255
line vty 0 15
access-class 10 in
end
Disable SSH Management
allDisable SSH management if not required, use alternative management methods
configure terminal
no ip ssh server
end
🧯 If You Can't Patch
- Implement strict access controls for SSH management interfaces
- Monitor SSH logs for unusual configuration changes or privilege escalation attempts
🔍 How to Verify
Check if Vulnerable:
Check device model and firmware version against Cisco advisory. Use 'show version' command.Check Version:
show version | include VersionVerify Fix Applied:
Verify firmware version is updated to fixed version listed in Cisco advisory.📡 Detection & Monitoring
Log Indicators:
- Unusual SSH connections from unexpected sources
- Configuration changes via SSH outside maintenance windows
- Privilege escalation attempts in system logs
Network Indicators:
- SSH connections to AP management interfaces from non-admin workstations
- Unusual outbound connections from APs after SSH sessions
SIEM Query:
source="cisco_ap_logs" AND (event_type="ssh_login" AND user="admin") OR (event_type="config_change" AND method="ssh")