How Hack OpenPLC for Industrial Cybersecurity Testing

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OpenPLC is a popular open-source Programmable Logic Controller (PLC) used in industrial automation. While it’s widely adopted for education and research, it’s also a prime target for cybersecurity testing. Below, we explore how to assess OpenPLC security and harden it against attacks.

You Should Know: OpenPLC Security Testing & Hardening

1. Setting Up OpenPLC for Penetration Testing

Before testing, deploy OpenPLC in a controlled lab environment: 

 Install dependencies (Ubuntu/Debian) 
sudo apt update 
sudo apt install git build-essential automake libtool pkg-config

Clone and compile OpenPLC 
git clone https://github.com/thiagoralves/OpenPLC_v3.git 
cd OpenPLC_v3 
./install.sh

2. Scanning for Vulnerabilities

Use Nmap to identify open ports and services:

nmap -sV -p- <OpenPLC_IP>

Common OpenPLC ports:

  • 502/TCP (Modbus)
  • 20000/TCP (Web interface)

3. Exploiting Modbus Protocol

OpenPLC uses Modbus, which is often unsecured. Use mbclient (from libmodbus) to interact: 

mbclient -m rtu -a 1 -t 4 -r 1 -c 1 <OpenPLC_IP>

For deeper attacks, use Metasploit:

msfconsole 
use auxiliary/scanner/scada/modbusdetect 
set RHOSTS <OpenPLC_IP> 
run

4. Web Interface Exploitation

OpenPLC’s web dashboard (port 20000) may have vulnerabilities. Test for SQLi/XSS: 

sqlmap -u "http://<OpenPLC_IP>:20000/login" --data="username=admin&password=test"

5. Securing OpenPLC

  • Disable Modbus TCP if unused: Edit `plc_settings.json`
  • Enable Authentication: 
    echo "admin:$(openssl passwd -6 'StrongPassword')" > /etc/openplc/.htpasswd
  • Firewall Rules: 
    sudo ufw allow from 192.168.1.0/24 to any port 20000 
sudo ufw enable

What Undercode Say

OpenPLC is a powerful tool but must be secured before deployment in industrial environments. Key takeaways:
– Always change default credentials (admin/openplc).
– Restrict network access to trusted IPs.
– Monitor logs for suspicious Modbus traffic.
– Use VPNs for remote access instead of exposing ports.

For further hardening:

 Disable unnecessary services 
sudo systemctl disable openplc_modbus 
sudo systemctl stop openplc_modbus

Expected Output: A secured OpenPLC instance with minimal attack surface, logged access attempts, and encrypted communications.

Relevant URL:

References:

Reported By: Thiago Alves – Hackers Feeds
Extra Hub: Undercode MoN
Basic Verification: Pass ✅

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