CVE-2023-33238
📋 TL;DR
This CVE describes a command injection vulnerability in Moxa TN-4900 and TN-5900 series industrial routers. Insufficient input validation in certificate management allows attackers to execute arbitrary commands remotely. Organizations using affected firmware versions are at risk.
💻 Affected Systems
- Moxa TN-4900 Series
- Moxa TN-5900 Series
📦 What is this software?
⚠️ Risk & Real-World Impact
Worst Case
Full device compromise leading to lateral movement within industrial networks, data exfiltration, or disruption of critical operations.
Likely Case
Unauthorized access to device configuration, installation of backdoors, or disruption of network connectivity.
If Mitigated
Limited impact with proper network segmentation and access controls preventing exploitation attempts.
🎯 Exploit Status
Requires access to certificate management function. No public exploit code available at time of analysis.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: TN-4900: v1.2.5 or later; TN-5900: v3.4 or later
Vendor Advisory: https://www.moxa.com/en/support/product-support/security-advisory/mpsa-230402-tn-5900-and-tn-4900-series-web-server-multiple-vulnerabilities
Restart Required: Yes
Instructions:
1. Download latest firmware from Moxa support portal. 2. Backup device configuration. 3. Upload firmware via web interface. 4. Apply firmware update. 5. Restart device. 6. Restore configuration if needed.
🔧 Temporary Workarounds
Disable Web Interface
allDisable HTTP/HTTPS web management interface if not required for operations
Network Access Control
allRestrict access to management interface using firewall rules
🧯 If You Can't Patch
- Implement strict network segmentation to isolate affected devices
- Monitor for unusual certificate management activity and command execution attempts
🔍 How to Verify
Check if Vulnerable:
Check firmware version via web interface: System > System Information > Firmware VersionCheck Version:
No CLI command available; check via web interfaceVerify Fix Applied:
Verify firmware version is TN-4900 v1.2.5+ or TN-5900 v3.4+📡 Detection & Monitoring
Log Indicators:
- Unusual certificate upload/modification events
- Unexpected system command execution in logs
Network Indicators:
- Unusual outbound connections from device
- Certificate management requests from unexpected sources
SIEM Query:
source="moxa-router" AND (event="certificate_upload" OR event="command_execution")