CVE-2018-20218
📋 TL;DR
CVE-2018-20218 is a critical command injection vulnerability in Teracue ENC-400 devices that allows attackers to execute arbitrary shell commands via the password parameter in the login form. This affects all ENC-400 devices with firmware version 2.56 and below. Attackers can gain complete control of affected devices without authentication.
💻 Affected Systems
- Teracue ENC-400
📦 What is this software?
⚠️ Risk & Real-World Impact
Worst Case
Full system compromise allowing attacker to install persistent backdoors, pivot to internal networks, exfiltrate data, or render devices inoperable.
Likely Case
Remote code execution leading to device takeover, credential theft, and use as attack platform against internal networks.
If Mitigated
Limited to login page access attempts if properly segmented and monitored.
🎯 Exploit Status
Simple curl commands can exploit this vulnerability. Public exploit scripts are available in disclosure reports.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Firmware 2.57 or later
Vendor Advisory: https://www.teracue.com/en/support/security-advisories/
Restart Required: Yes
Instructions:
1. Download latest firmware from Teracue support portal. 2. Backup device configuration. 3. Upload firmware via web interface. 4. Apply firmware update. 5. Reboot device. 6. Restore configuration if needed.
🔧 Temporary Workarounds
Network Segmentation
allIsolate ENC-400 devices from internet and restrict access to trusted management networks only.
Web Interface Disable
linuxDisable web management interface if not required, using CLI or serial console for management.
telnet <device_ip>
configure terminal
no web-management
🧯 If You Can't Patch
- Implement strict network ACLs allowing only trusted IPs to access device management interface
- Deploy WAF or reverse proxy with command injection filtering in front of devices
🔍 How to Verify
Check if Vulnerable:
Check firmware version via web interface at /system.html or via SSH/telnet using 'cat /etc/version'Check Version:
ssh admin@<device_ip> 'cat /etc/version' or check web interface system pageVerify Fix Applied:
Confirm firmware version is 2.57 or higher and test login form with command injection payloads (e.g., password=test';id;')📡 Detection & Monitoring
Log Indicators:
- Unusual shell commands in system logs
- Multiple failed login attempts with special characters
- New user accounts or processes
Network Indicators:
- HTTP POST requests to /check.lp with shell metacharacters in parameters
- Outbound connections from device to unexpected destinations
SIEM Query:
source="enc-400" AND (url="/check.lp" AND (password="*;*" OR password="*|*" OR password="*`*"))