ICS Security Checklist: 8 Proven Steps to Protect Industrial Control Systems

Industrial control systems (ICS) govern critical infrastructure—from nuclear plants to oil refineries. A cyberattack can halt operations, unlike a traditional data breach that primarily affects IT data stores.

Because OT (operational technology) devices and networks differ from conventional IT, securing them requires a dedicated approach. Below are eight evidence‑based principles that industry professionals can adopt to reduce risk and build resilience.

1. Inventory and Understand Your Assets

Many facilities lack a clear picture of what equipment they have. Bill Malik, VP of Infrastructure Strategies at Trend Micro, notes that “most organizations don’t know what technology they’ve got deployed.”

Operational technology assets include PLCs, SCADA, and DCS systems—often hidden behind non‑networked devices or legacy equipment from the 1960s and 1970s. Counting servers or IP addresses alone misses this complexity. Sean Peasley of Deloitte explains that an OT inventory can be done passively by specialized vendors to avoid disrupting processes.

2. Adopt a Trusted Framework

Standards such as ISA/IEC 62443, ISO/IEC 27001, the NIST Cybersecurity Framework, NERC CIP, MITRE ATT&CK for Industrial Control Systems, and UL 2900 provide common language and controls that bridge IT and OT.

Start with one framework that fits your environment; the overlap among these standards will give you a holistic cybersecurity mindset.

3. Establish a Cyber Disaster Recovery Plan

A framework should translate into plain‑English guidance for detection, response, and recovery. Haward‑Grau emphasizes the need for actionable plans: “How do I identify and protect things? How will I detect, respond and recover?”

4. Invest in Cyber Insurance

Because many legacy assets cannot be patched, insurers often require compensating controls. Rather than insuring individual devices, cover industrial processes. Be aware of exclusions even with a robust security posture.

5. Apply the Principle of Least Privilege

Limit access to OT networks and devices. Use firewalls to block unnecessary traffic, white‑list allowed processes, and enforce unique credentials for remote maintenance. Malik warns against using generic PCs without hardening them.

6. Consider a Bug‑Bounty Program

Bug bounties help identify vulnerabilities early, especially as IIoT and 5G expand. However, they may overwhelm organizations with unpatched, legacy systems. Use them strategically.

7. Manage Third‑Party Risk

Peasley notes that large companies face thousands of suppliers and sub‑components. A formal third‑party risk program must assess software, hardware, and embedded systems throughout the supply chain.

8. Leverage Safety Program Practices

Traditional safety protocols—like process hazard analysis—can be extended to cybersecurity. The American Institute of Chemical Engineers recommends integrating cyber risks into these analyses. While safety‑instrumented systems can be vulnerable, they remain essential defense layers; retrofitting them is not advised without redesigning for cyber resilience.

By following these eight steps, industrial operators can strengthen their defenses, align with best practices, and protect mission‑critical operations from evolving cyber threats.