CVE-2021-46560
📋 TL;DR
This vulnerability allows remote attackers to execute arbitrary commands on Moxa TN-5900 secure routers through command injection in the firmware. Attackers could potentially take full control of affected devices, leading to device damage or network compromise. Organizations using Moxa TN-5900 routers through version 3.1 are affected.
💻 Affected Systems
- Moxa TN-5900 Secure Routers
📦 What is this software?
⚠️ Risk & Real-World Impact
Worst Case
Complete device compromise leading to permanent device damage, network disruption, and lateral movement into connected networks.
Likely Case
Remote code execution allowing attackers to reconfigure devices, intercept traffic, or use devices as network footholds.
If Mitigated
Limited impact if devices are behind firewalls with strict network segmentation and access controls.
🎯 Exploit Status
Command injection vulnerabilities typically have low exploitation complexity and can be exploited with simple HTTP requests containing malicious payloads.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Version 3.2 or later
Vendor Advisory: https://www.moxa.com/en/support/product-support/security-advisory/tn-5900-secure-routers-vulnerabilitiestxt
Restart Required: Yes
Instructions:
1. Download firmware version 3.2 or later from Moxa support portal. 2. Backup current configuration. 3. Upload new firmware via web interface or CLI. 4. Reboot device. 5. Verify firmware version after reboot.
🔧 Temporary Workarounds
Network Segmentation
allIsolate TN-5900 devices from untrusted networks and restrict access to management interfaces.
Access Control Lists
allImplement strict firewall rules to limit which IP addresses can communicate with the device management interfaces.
🧯 If You Can't Patch
- Deploy network-based intrusion prevention systems (IPS) to detect and block command injection attempts
- Implement strict network segmentation to isolate vulnerable devices from critical network segments
🔍 How to Verify
Check if Vulnerable:
Check firmware version via web interface (System > System Information) or CLI command 'show version'Check Version:
show versionVerify Fix Applied:
Verify firmware version is 3.2 or higher using same methods as checking vulnerability📡 Detection & Monitoring
Log Indicators:
- Unusual command execution in system logs
- Multiple failed authentication attempts followed by successful access
- Unexpected configuration changes
Network Indicators:
- Unusual outbound connections from router
- Traffic patterns inconsistent with normal operation
- HTTP requests with shell metacharacters or command injection patterns
SIEM Query:
source="tn-5900-logs" AND ("cmd.exe" OR "bash" OR "sh" OR "|" OR ";" OR "$" OR "`")