FREE OT/ICS Cybersecurity Training On TryHackMe: Master PLCs, HMI Simulators & SCADA Defense + Video

Introduction:

Operational Technology (OT) and Industrial Control Systems (ICS) form the backbone of critical infrastructure—power grids, water treatment plants, and manufacturing lines—yet they remain dangerously exposed to cyber threats. Unlike traditional IT security, OT environments prioritize safety and availability over confidentiality, requiring specialized knowledge of programmable logic controllers (PLCs), human-machine interfaces (HMIs), and SCADA protocols. A new free TryHackMe room now offers hands-on experience with simulated HMIs, bridging the gap between theoretical OT concepts and practical defense.

Learning Objectives:

Understand core OT/ICS components: PLCs, SCADA, HMIs, and their operational roles
Distinguish between IT and OT cybersecurity priorities, threat models, and response strategies
Perform basic HMI simulation interactions and identify common OT network vulnerabilities

You Should Know:

Simulating an HMI & Interacting with a Virtual PLC

The TryHackMe room includes a simulated Human-Machine Interface (HMI)—a dashboard that operators use to monitor and control industrial processes. This simulation mimics real-world PLC behavior, allowing you to toggle switches, read sensor values, and observe logic execution without physical hardware.

Step‑by‑Step Guide – Accessing and Exploring the HMI Simulation:

Access the free room – Navigate to `https://tryhackme.com` (or use the direct link: https://lnkd.in/edv7YM8U) and create a free account if needed.
2. Start the machine – Click “Start Machine” to launch the in-browser virtual environment (typically a Linux VM with the HMI interface pre‑configured).
3. Open the HMI – Once the machine is ready, open the provided URL (usually `http://MACHINE_IP:8080` or similar) in the browser inside the VM.

4. Identify components – The HMI will display:

Tank levels (percentage or bar graph)
Pump/Valve status (green = on/red = off)
Toggle buttons (start/stop, open/close)
Alarm indicators (high temperature, low pressure)

Perform basic actions – Click a pump “Start” button; observe the tank level change or a conveyor belt animation. Note how the PLC logic processes the input and updates the HMI in near real‑time.
Capture network traffic (optional learning) – While interacting, run `tcpdump` in the VM terminal to see OT protocols (e.g., Modbus/TCP on port 502):

sudo tcpdump -i eth0 port 502 -n -vv

This reveals read/write commands sent to the PLC.

What this teaches: HMIs are a primary attack surface—if an attacker compromises the HMI interface, they can manipulate physical processes (e.g., open a steam valve, overfill a tank). Defenders must isolate HMI traffic, apply strict access controls, and monitor for anomalous commands.

Comparing OT vs. IT Cybersecurity – Practical Checklist

Many IT security practices break down in OT environments. Patching a Windows server weekly is standard; patching a PLC firmware may require a production shutdown approved weeks in advance. Understanding these differences is critical for cross‑over defenders.

Step‑by‑Step Guide – Assess & Harden an OT Network Using IT/OT Differences:

Inventory OT assets – Use `nmap` (sparingly, as aggressive scans can crash legacy PLCs) to discover devices:
```
sudo nmap -sS -p 502,44818,2222,4840 192.168.1.0/24 --max-rtt-timeout 100ms
```
(Common OT ports: Modbus 502, EtherNet/IP 44818, CIP 2222, OPC UA 4840)
Identify insecure protocols – Many OT devices use plaintext Modbus/TCP. Capture and analyze:
```
sudo tcpdump -r ot_traffic.pcap -A | grep -i "read|write|coil"
```
Look for `write_coil` commands that could turn pumps on/off.
Apply defense‑in‑depth (Purdue Model) – Segment OT from IT using firewalls. Example `iptables` rule to allow only specific HMI to PLC:
```
iptables -A FORWARD -s 192.168.1.100 -d 192.168.1.200 -p tcp --dport 502 -j ACCEPT
iptables -A FORWARD -j DROP
```
Implement change management – Unlike IT, never patch or reboot a PLC without maintenance window. Use virtual patching via network-based IPS (e.g., Snort rule to detect unauthorized Modbus writes):
```
alert tcp any any -> any 502 (msg:"Modbus Write Coil"; content:"|05|"; depth:1; sid:10001;)
```
Test incident response – Simulate a compromised HMI. From Linux attacker machine, use `modbus-cli` to write a fake coil:
```
modpoll -m tcp -a 1 -c 1 -r 10 192.168.1.200 1
```
(Writes coil 10 to ON – verify if alarm triggers.)

What this teaches: OT security focuses on availability and safety → no reboots, no aggressive scanning, no unplanned changes. Use passive monitoring (network taps), unidirectional gateways, and physical safety backups.

Free Resources & Hands‑On Labs for OT/ICS Cybersecurity

Beyond the TryHackMe room, Mike Holcomb provides free videos and a newsletter to deepen your OT/ICS skills. Combine these to build a complete learning path.

Step‑by‑Step Guide – Build Your Own OT Home Lab on a Budget:

Subscribe to free video series – https://lnkd.in/eif9fkVg (YouTube) – watch introductory modules on PLC programming and SCADA architecture.
Join the newsletter – https://lnkd.in/ePTx-Rfw – receive weekly OT security tips, CVE alerts for ICS devices, and lab walkthroughs.
Set up a virtual PLC simulator – Use `OpenPLC` (open source) on Ubuntu:
```
sudo apt update && sudo apt install openplc -y
cd /opt/openplc && sudo ./start_openplc.sh
```
Access web interface at `http://localhost:8080` – upload ladder logic programs.
Configure an HMI simulator – Install `ScadaBR` (Java‑based) or use FUXA:
```
git clone https://github.com/frangoteam/FUXA
cd FUXA && npm install && npm start
```
Connect FUXA to OpenPLC via Modbus/TCP (default port 502).
Attack and defend in a closed environment – Use `Metasploit` auxiliary modules for Modbus scanning:
```
use auxiliary/scanner/scada/modbus_findunitid
set RHOSTS 127.0.0.1
run
```
Then implement defense: enable Modbus firewalling, use write‑only coils for critical commands, and monitor logs with journalctl -u openplc -f.

What this teaches: A virtual OT lab costs nothing but teaches protocol analysis, PLC logic, and attack vectors without risking real equipment. Combine free video lessons with hands-on simulation to master ICS defense.

4. Hardening PLCs & Responding to OT Incidents

PLCs often run on embedded real‑time operating systems (e.g., VxWorks, bare metal) without antivirus or host‑based logging. Hardening requires network‑level controls and physical security.

Step‑by‑Step Guide – PLC Hardening Checklist:

Disable unused protocols – On a Siemens S7 or Rockwell PLC, use vendor software (TIA Portal, Studio 5000) to turn off unused services (HTTP, SNMP, FTP).
Implement strict firewall rules – On an industrial firewall (e.g., Cisco IE series), allow only specific IP/MAC addresses:
```
access-list 100 permit tcp host 10.0.0.10 host 10.0.0.20 eq 502
access-list 100 deny ip any any
```

Enable logging (if supported) – On Stratix switches, mirror OT traffic to a passive IDS:

monitor session 1 source interface gig1/0/1 both
monitor session 1 destination interface gig1/0/24

Create a “last resort” safety kill switch – Hardwired relay or emergency stop button that physically cuts power to actuators—independent of PLC logic.

Write an OT incident response playbook snippet – Example for suspected HMI compromise:

On Linux monitoring host, check for unauthorized Modbus writes every minute
while true; do
tcpdump -i eth0 -c 10 port 502 -A | grep -i "write" >> /var/log/ot_alerts.log
sleep 60
done

Alert security team if >5 writes/minute to same coil.

What this teaches: OT incident response is manual and cautious — never remotely reboot a crashed PLC. Instead, invoke physical bypass or bring in vendor support. Document every step to avoid catastrophic process failure.

5. Using TryHackMe for OT/ICS Career Development

The free room is part of a growing OT security learning path. Use it to build resume‑ready skills and earn badges.

Step‑by‑Step Guide – Maximize Your TryHackMe OT Experience:

Complete the room – Answer all questions; take screenshots of the simulated HMI interactions.
Document your learning – Create a GitHub repository with:

– Modbus packet captures (.pcap files)
– Custom Snort/Suricata rules for OT threats
– A one‑page “OT vs IT cheat sheet”

Share your progress – Post on LinkedIn tagging Mike Holcomb and TryHackMe (use ICSsecurity OTcyber).
Move to Room 2 (launching soon) – Expect deeper PLC exploitation, firmware analysis, or MITRE ATT&CK for ICS mapping.
Join the OT/ISC community – Participate in free ICS security Slack/Discord groups; attend S4x24 or Dragos’ OT Summit (some offer free virtual tickets).

Linux/Windows Commands to Practice After the Room:

| Purpose | Linux Command | Windows PowerShell Equivalent |

|||-|

What Undercode Say:

OT security is NOT IT security – Prioritize availability, safety, and physical control. Never scan aggressively or patch without a maintenance window.
Free training bridges the gap – TryHackMe’s simulated HMI and Mike Holcomb’s video series lower the barrier to entry for critical infrastructure defense, making hands-on OT skills accessible to anyone with a browser.
Small steps prevent big disasters – Even basic actions like isolating HMI traffic, logging Modbus commands, and implementing hardware e-stops can stop 80% of real‑world OT attacks (e.g., TRITON, Industroyer).
Community and newsletters accelerate growth – Following OT/ICS experts and joining free labs leads to faster skill acquisition than isolated study. The field needs more defenders—start today.

Prediction:

Within 18 months, 60% of OT/ICS security training will incorporate simulated HMI/PLC environments due to the shortage of physical lab access and rising regulator pressure (e.g., NERC CIP, IEC 62443). We will see LMS platforms like TryHackMe and HackTheBox release dedicated OT tracks, followed by certification bodies (GICSP, ISA/IEC 62443) integrating simulation-based exams. Simultaneously, attackers will increasingly target IT-OT convergence points—like engineering workstations and historians—demanding defenders master both domains. The free resources highlighted here will become foundational references for new OT security analysts entering the workforce.

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