CVE-2020-20184
📋 TL;DR
CVE-2020-20184 is a critical remote code execution vulnerability in GateOne web-based terminal emulator. Attackers can execute arbitrary commands by injecting shell metacharacters into the SSH port field during connection attempts. This affects all GateOne installations with SSH functionality enabled.
💻 Affected Systems
- GateOne
📦 What is this software?
Gateone by Liftoffsoftware
⚠️ Risk & Real-World Impact
Worst Case
Complete system compromise allowing attackers to execute arbitrary commands with the privileges of the GateOne process, potentially leading to full server takeover, data exfiltration, and lateral movement.
Likely Case
Remote code execution leading to unauthorized access, data theft, and potential deployment of malware or backdoors on affected systems.
If Mitigated
Limited impact if GateOne runs with minimal privileges, network segmentation is in place, and input validation blocks malicious attempts.
🎯 Exploit Status
Exploitation is straightforward - attackers simply need to send specially crafted SSH connection requests with shell metacharacters in the port field.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Fixed in the latest version after the vulnerability disclosure
Vendor Advisory: https://github.com/liftoff/GateOne/issues/736
Restart Required: Yes
Instructions:
1. Update GateOne to the latest version. 2. Apply the patch that adds proper input validation/sanitization for the port field. 3. Restart the GateOne service.
🔧 Temporary Workarounds
Disable SSH functionality
allTemporarily disable SSH connections in GateOne configuration
Edit GateOne configuration to set 'ssh': false or remove SSH-related settings
Network access restrictions
linuxRestrict network access to GateOne service using firewall rules
iptables -A INPUT -p tcp --dport [GateOne_port] -s [trusted_ips] -j ACCEPT
iptables -A INPUT -p tcp --dport [GateOne_port] -j DROP
🧯 If You Can't Patch
- Implement strict network segmentation and firewall rules to limit access to GateOne service
- Run GateOne with minimal privileges (non-root user) and in a containerized/sandboxed environment
🔍 How to Verify
Check if Vulnerable:
Check if GateOne version is unpatched and SSH functionality is enabled. Test by attempting to connect with shell metacharacters in port field.Check Version:
Check GateOne version in web interface or configuration filesVerify Fix Applied:
Verify GateOne has been updated to latest version and test that shell metacharacters in port field are properly sanitized/rejected.📡 Detection & Monitoring
Log Indicators:
- Unusual SSH connection attempts with non-numeric port values
- Shell metacharacters in connection logs
- Failed connection attempts with suspicious port parameters
Network Indicators:
- SSH connection attempts to GateOne with unusual port values
- Traffic patterns suggesting command injection attempts
SIEM Query:
source="GateOne" AND (port="*;*" OR port="*|*" OR port="*&*" OR port="*`*" OR port="*$(*" OR port="*>*" OR port="*<*")