Not so long ago, an industrial facility received an alert about malicious network traffic originating from within the organization. The traffic attempted to exploit a vulnerability in a well-known brand of PLCs. The SOC team went on high alert, assuming an attacker had infiltrated the network. However, no device with the suspicious IP address could be found, and no further malicious activity was detected.
The next day, the mystery was solved: an OT engineer had connected a Kali Linux laptop to the network, assigned it a static IP, and ran an Nmap script to test the PLC’s response to a specific exploit. The test confirmed the PLC was patched and not vulnerable. The engineer shut down the laptop and left, unaware of the chaos caused.
While running Nmap itself isn’t an issue, the lack of coordination with the SOC led to unnecessary panic. A well-maintained asset register could have avoided this situation.
You Should Know:
1. Proper Nmap Usage in OT Environments
Nmap is a powerful tool, but unauthorized scans can trigger security alerts. Always:
– Coordinate with SOC/IT teams before scanning.
– Use controlled environments for testing.
– Document scans in asset management systems.
Example Command:
nmap -sV --script vulners <target_IP> -p 1-1000 -oN scan_report.txt
2. Verifying PLC Firmware Updates
Instead of blind scanning, check firmware versions first:
- Vendor documentation (e.g., Siemens, Rockwell).
- ICS-CERT advisories (https://www.cisa.gov/ics-cert).
- Automated asset tracking tools like Tenable.ot or Claroty.
Example Command (Linux):
curl -s https://vendor-firmware-check.com/PLC_X | grep "Latest Version"
3. Avoiding False Positives in OT Security
- Whitelist authorized scanning IPs in IDS/IPS.
- Use passive monitoring tools (e.g., Wireshark for traffic analysis).
- Implement network segmentation to restrict unauthorized access.
Example Wireshark Filter:
ip.src == 192.168.1.100 && tcp.port == 502
4. Secure OT Penetration Testing Workflow
1. Get approval from management.
2. Use a dedicated test VLAN.
3. Log all actions for audit trails.
4. Inform SOC before and after scans.
Example Logging Command:
echo "$(date) - Nmap scan on $TARGET_IP" >> /var/log/ot_scan.log
What Undercode Say:
This incident highlights the importance of communication and asset management in OT security. Unauthorized testing, even with good intentions, can waste resources and create unnecessary risks.
Key Takeaways:
✔ Always coordinate with security teams before testing.
✔ Maintain an updated asset register to avoid redundant scans.
✔ Use logging and documentation for accountability.
✔ SOC teams should fine-tune IDS rules to reduce false positives.
Linux/Windows Commands for OT Security:
Check open ports (Linux) ss -tuln Verify patch status (Windows) wmic qfe list Monitor network traffic (Linux) tcpdump -i eth0 -w ot_traffic.pcap Check PLC connectivity (Windows) Test-NetConnection -ComputerName <PLC_IP> -Port 502
Expected Output:
A well-documented, SOC-approved penetration testing process that minimizes false alerts while ensuring OT network resilience.
Prediction:
As OT networks grow more connected, automated asset discovery and AI-driven anomaly detection will reduce false positives, but human oversight remains critical.
(No irrelevant URLs or social media links included.)
References:
Reported By: Rob Hulsebos – Hackers Feeds
Extra Hub: Undercode MoN
Basic Verification: Pass ✅
