Mastering ICS/SCADA Security: Key Takeaways from GIAC GRID Certification

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Introduction

Industrial Control Systems (ICS) and Supervisory Control and Data Acquisition (SCADA) security is critical for protecting critical infrastructure. The GIAC Response and Industrial Defense (GRID) certification, offered by SANS Institute, equips professionals with hands-on skills to defend operational technology (OT) environments. This article explores key technical concepts, commands, and methodologies from the GRID course.

Learning Objectives

  • Understand ICS/SCADA security fundamentals and incident response.
  • Learn practical commands for interacting with PLCs and HMIs.
  • Explore techniques for securing industrial networks.

1. ICS Network Segmentation with Firewall Rules

Command (Linux):

sudo iptables -A INPUT -p tcp --dport 502 -s 192.168.1.100 -j ACCEPT 
sudo iptables -A INPUT -p tcp --dport 502 -j DROP

What This Does:

  • Allows Modbus TCP (port 502) traffic only from a trusted IP (192.168.1.100).
  • Drops all other Modbus traffic to prevent unauthorized access.

Step-by-Step:

1. Identify critical ICS devices (PLCs, HMIs).

2. Restrict access using IP-based firewall rules.

3. Log dropped packets for monitoring:

sudo iptables -A INPUT -p tcp --dport 502 -j LOG --log-prefix "Modbus Blocked: "

2. PLC Memory Dump for Forensic Analysis

Tool: `modbus-cli` (Python)

modbus read --ip=10.0.0.5 --port=502 --address=0 --count=100 --unit=1

What This Does:

  • Reads 100 registers from a Modbus PLC at 10.0.0.5.
  • Useful for detecting unauthorized changes in ladder logic or setpoints.

Step-by-Step:

1. Install `modbus-cli`:

pip install modbus-cli

2. Compare dump results against baseline to identify tampering.

3. Detecting SCADA Protocol Anomalies

Tool: Wireshark Filter

modbus.function_code == 0x10 && frame.time_delta > 1s

What This Does:

  • Flags delayed Modbus “Write Multiple Registers” requests (potential stuxnet-like attacks).

Step-by-Step:

1. Capture ICS network traffic.

2. Analyze timing anomalies in protocol execution.

4. Hardening Windows HMI Workstations

Command (Windows):

Set-NetFirewallProfile -Profile Domain,Public,Private -Enabled True 
Disable-WindowsOptionalFeature -Online -FeatureName SMB1Protocol

What This Does:

  • Enables firewall across all profiles.
  • Disables SMBv1 to prevent worm propagation (e.g., WannaCry).

5. ICS Patch Management with Ansible

Playbook Snippet:

- hosts: plcs 
tasks: 
- name: Update Schneider PLC firmware 
uri: 
url: "http://{{ inventory_hostname }}/firmware_update" 
method: POST 
body: "{{ lookup('file','firmware.bin') | b64encode }}"

What This Does:

  • Automates secure firmware updates for PLCs.

What Undercode Say

  • Key Takeaway 1: GRID emphasizes physical interaction with PLCs—a rare skill in traditional cybersecurity.
  • Key Takeaway 2: Overconfidence in exams is risky; ICS attacks often exploit subtle misconfigurations.

Analysis:

The GRID certification bridges the gap between IT and OT security. As critical infrastructure faces rising threats (Dragos reports a 50% YoY increase in ICS-targeted malware), hands-on training like SANS’ ICS515 is indispensable. Future attacks will likely abuse IIoT devices, making GRID’s focus on device-level defense prescient.

Prediction:

By 2026, AI-driven ICS attacks (e.g., adversarial machine learning against PLC logic) will emerge, requiring advanced GRID-like defensive skills.

Note: Always test commands in a lab environment before production use.

IT/Security Reporter URL:

Reported By: Nazrulaffiq Im – Hackers Feeds
Extra Hub: Undercode MoN
Basic Verification: Pass ✅

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