How to Protect Your PLCs from Cyber Attacks: What You Need to Know

As industrial environments become more connected, cybersecurity threats targeting operational technology (OT) are on the rise. A recent joint advisory from U.S. government agencies highlights ongoing cyber exploitation of internet-connected OT devices—including PLCs.

For manufacturers and industrial teams, this is a reminder: securing your control systems is no longer optional—it’s essential.

Why PLC Cybersecurity Matters

PLCs are at the core of your operation. If compromised, the impact can go far beyond IT issues:

• Safety risks for personnel
• Unplanned downtime
• Production disruptions
• Equipment damage
• Potential harm to asset integrity
• Misappropriation of intellectual property
  

Unlike traditional IT systems, OT environments are designed for uptime, which can make them more vulnerable if not properly secured.

The Biggest Risk: Internet-Exposed Controllers

One of the most common and dangerous vulnerabilities is the exposure of controllers directly to the public internet.

Attackers actively scan for these devices—and once found, they can attempt unauthorized access, disrupt operations, or deploy malicious code.

What to do:

• Remove PLCs from direct internet access
• Use firewalls to isolate your network
• Enable secure remote access (VPN instead of open ports)

Built-In Security Features You Should Be Using

Many modern Rockwell Automation controllers include powerful security capabilities—but they’re not always enabled by default.

These may include:

• User authentication and role-based access
• Encrypted communications (CIP Security)
• Ensure the controller mode switch is in RUN
• Secure firmware and update validation
  

👉 Rockwell’s System Security Design Guidelines provide a deeper dive into how to properly configure these features.

Take a Defense-in-Depth Approach

There’s no single solution to OT cybersecurity. The most effective approach is defense-in-depth—layering multiple protections across your environment.

This includes:

• Network segmentation (separating IT and OT systems)
• Firewalls and secure remote access
• Monitoring and anomaly detection
• Regular patching and updates

👉 You can explore validated architectures in Rockwell’s Industrial Network Design Guides, which show how to build secure, scalable industrial networks.

Staying Ahead of Emerging Threats

Cyber threats are constantly evolving, and industrial environments are increasingly becoming targets.

Staying protected means:

• Use the latest controller firmware and stay up to date using Rockwell's OT patch management
• Following vendor security advisories
• Regularly reviewing your network architecture
• Training your team on cybersecurity best practices

How ES&E Can Help

At ES&E, we work with customers to help strengthen their OT cybersecurity posture through:

• Network design and segmentation strategies
• Secure remote access solutions
• Guidance aligned with Rockwell's best practices
• Ongoing support and training

You can also explore our cybersecurity playlist for additional tips and best practices. 

Key Takeaways

Cybersecurity in industrial environments doesn’t have to be overwhelming—but it does require action.

Start with the basics:
✔ Remove internet exposure
✔ Enable controller security features
✔ Layer your defenses

From there, you can build a more resilient and secure operation.

Learn more at the Rockwell Automation Trust Center.