Still Relevant, Still Critical: A Must-Read on ICS Cybersecurity

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The SANS Institute’s White Paper on the Five ICS Cybersecurity Critical Controls (by Robert M. Lee and Tim Conway) remains a cornerstone resource for securing Industrial Control Systems (ICS) and Operational Technology (OT). The framework emphasizes outcome-focused, risk-based strategies rooted in real-world incidents.

The Five Critical Controls:

1. ICS Incident Response – Scenario-driven, not checklist-based.

  1. Defensible Architecture – Focus on resilience, not just segmentation.
  2. Network Visibility & Monitoring – Protocol-aware and physics-aware.
  3. Secure Remote Access – MFA, choke-points, and break-inspect strategies.
  4. Risk-Based Vulnerability Management – Prioritize real risk over CVEs.

You Should Know:

1. ICS Incident Response

  • Practice: Use `log2timeline` (Plaso) for ICS forensic timeline analysis:
    log2timeline.py --storage-file timeline.plaso /path/to/evidence
    
  • Command: Monitor ICS logs with `journalctl` (Linux):
    journalctl -u modbus.service --no-pager -f
    

2. Defensible Architecture

  • Tool: Implement Unidirectional Gateways (Data Diodes) to enforce one-way traffic.
  • Command: Check Linux firewall rules (iptables):
    iptables -L -n -v | grep DROP
    

3. Network Visibility & Monitoring

  • Tool: Use Wireshark with ICS protocol dissectors (MODBUS, DNP3):
    wireshark -k -i eth0 -Y "modbus || dnp3"
    
  • Command: Detect anomalies with `snort` (ICS rules):
    snort -c /etc/snort/snort.conf -A console -q
    

4. Secure Remote Access

  • Practice: Enforce Multi-Factor Authentication (MFA) for SSH:
    sudo nano /etc/ssh/sshd_config 
    Add: 
    AuthenticationMethods publickey,keyboard-interactive
    
  • Tool: Use Guacamole for secure web-based access.

5. Risk-Based Vulnerability Management

  • Command: Scan for ICS vulnerabilities with nmap:
    nmap -sV --script vulners <target>
    
  • Tool: OpenVAS for ICS-specific risk assessment.

What Undercode Say:

  • “Defensible > Secure”: Harden ICS systems with `chroot` jails:
    chroot /secure_path /bin/bash
    
  • Monitor PLCs using `pcp` (Performance Co-Pilot):
    pminfo -f modbus.registers.read
    
  • Windows ICS Security: Disable SMBv1:
    Disable-WindowsOptionalFeature -Online -FeatureName SMB1Protocol
    
  • Log Aggregation: Forward ICS logs via rsyslog:
    sudo nano /etc/rsyslog.conf 
    Add: 
    . @<log-server>:514
    

Expected Output: A resilient ICS environment with continuous monitoring, secure access, and actionable incident response.

Reference: SANS ICS Critical Controls

References:

Reported By: Ashok Kumar – Hackers Feeds
Extra Hub: Undercode MoN
Basic Verification: Pass ✅

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