OT Security: Protecting Industrial Control Systems

The OT Threat Landscape

Operational technology (OT) and industrial control systems (ICS) were once considered safe from cyber threats due to air gaps. That assumption is now obsolete.

Why OT is Different

OT systems often run legacy software that cannot be easily patched. Downtime for updates can cost millions, and many protocols were designed for reliability—not security.

Key OT Security Controls

Network segmentation — Separate OT networks from corporate IT networks using industrial DMZs and firewalls purpose-built for OT protocols.

Asset inventory — You cannot protect what you cannot see. Maintain a real-time inventory of every device on your OT network.

Vulnerability management — Prioritise patching based on risk to physical processes, not just CVSS scores.

Incident response planning — Develop OT-specific playbooks that account for the physical consequences of cyber incidents.

The Purdue Model in 2025

While the Purdue Reference Model remains useful, modern OT environments require layered security that goes beyond network zones.

The OT Threat Landscape

Operational technology (OT) and industrial control systems (ICS) were once considered safe from cyber threats due to air gaps. That assumption is now obsolete.

Why OT is Different

OT systems often run legacy software that cannot be easily patched. Downtime for updates can cost millions, and many protocols were designed for reliability—not security.

Key OT Security Controls

Network segmentation — Separate OT networks from corporate IT networks using industrial DMZs and firewalls purpose-built for OT protocols.

Asset inventory — You cannot protect what you cannot see. Maintain a real-time inventory of every device on your OT network.

Vulnerability management — Prioritise patching based on risk to physical processes, not just CVSS scores.

Incident response planning — Develop OT-specific playbooks that account for the physical consequences of cyber incidents.

The Purdue Model in 2025

While the Purdue Reference Model remains useful, modern OT environments require layered security that goes beyond network zones.