CVE-2020-3459
📋 TL;DR
This vulnerability in Cisco FXOS Software allows authenticated local attackers to execute arbitrary commands with root privileges by exploiting insufficient input validation in the CLI. It affects systems running vulnerable versions of Cisco FXOS where an attacker has local access. The risk is significant as it enables full system compromise.
💻 Affected Systems
- Cisco FXOS Software
📦 What is this software?
Firepower Extensible Operating System by Cisco
View all CVEs affecting Firepower Extensible Operating System →
Firepower Extensible Operating System by Cisco
View all CVEs affecting Firepower Extensible Operating System →
⚠️ Risk & Real-World Impact
Worst Case
An attacker gains complete control over the system, leading to data theft, service disruption, or lateral movement within the network.
Likely Case
An authenticated malicious insider or compromised account executes commands to escalate privileges, potentially causing operational impact.
If Mitigated
With strict access controls and monitoring, exploitation is limited, but risk remains if patching is delayed.
🎯 Exploit Status
Exploitation requires local authentication, making it less accessible but highly effective if credentials are compromised.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Refer to Cisco Security Advisory for specific fixed versions.
Vendor Advisory: https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-fxos-cmdinj-b63rwKPm
Restart Required: Yes
Instructions:
1. Review the Cisco advisory for affected versions. 2. Download and apply the recommended patch from Cisco. 3. Restart the device to ensure the fix is applied.
🔧 Temporary Workarounds
Restrict CLI Access
allLimit access to the CLI to only trusted administrators to reduce attack surface.
🧯 If You Can't Patch
- Implement strict access controls and monitor for unusual CLI activity.
- Isolate affected systems from critical network segments to limit potential damage.
🔍 How to Verify
Check if Vulnerable:
Check the FXOS version using 'show version' command and compare with Cisco advisory.Check Version:
show versionVerify Fix Applied:
After patching, verify the version is updated and test command injection attempts to ensure they are blocked.📡 Detection & Monitoring
Log Indicators:
- Unusual CLI command executions or privilege escalation attempts in system logs.
Network Indicators:
- None, as this is a local exploit.
SIEM Query:
Search for logs containing 'CLI' and 'root' or 'privilege' events from FXOS devices.