Implementing Defensible Architecture in Industrial Networks

Protecting industrial production and control systems from cyber threats requires more than just visibility and backups. While knowing your assets, monitoring for anomalies, and maintaining secure backups are foundational practices, these measures alone are not enough to prevent or contain cyber incidents—whether caused by targeted attacks or accidental actions, such as connecting an infected laptop or clicking a malicious email.

To build a defensible architecture, network segmentation is essential.

Segmentation is one of the 5 Critical Cybersecurity Controls for OT, and a core component of both the NIST Cybersecurity Framework and the NIS2 directive. These frameworks emphasize the importance of isolating critical assets and limiting the spread of potential intrusions across the network.

By organizing the OT environment into zones and conduits—consistent with IEC 62443—organizations can reduce their attack surface, enforce access controls, and prevent lateral movement between systems. Micro-segmentation, down to the level of individual machines or production lines, provides an added layer of protection for high-value assets such as your Crown Jewels.

This approach directly supports compliance with IEC 62443-3-3, especially Security Level 2 (SL2), which addresses threats from intentional compromise using simple tools with moderate resources—such as those used by organized threat actors. It also aligns with the risk management and incident containment requirements under NIS2, helping organizations demonstrate accountability and resilience.

By adopting a defensible architecture with strong segmentation, manufacturers gain greater control over remote access, reduce dependency on third-party-managed connections, and strengthen their overall cybersecurity posture in line with both industry standards and regulatory obligations.

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