When it comes to operational technology (OT), cybersecurity often feels like walking a tightrope—balancing the need for robust defense mechanisms with the complexities of legacy systems and industrial controls. The stakes? Everything from critical infrastructure like power grids and water treatment facilities to manufacturing plants. A cyber incident in these environments could have real-world consequences that go far beyond the digital realm. Recognizing the increasing vulnerability of OT systems, the National Security Agency (NSA), alongside the Australian Signals Directorate (ASD) and other partners, has laid out six key principles designed to fortify OT environments against cyber threats.

These principles offer a structured, yet flexible, approach to addressing cybersecurity concerns in OT environments. Let’s break down these guiding principles and their relevance to keeping critical infrastructure secure.

1. Know and Control Your OT Environment

The first step to protecting your OT environment is understanding it intimately. This principle calls for organizations to identify all the devices, systems, and networks in their OT environment. Many OT systems were not designed with cybersecurity in mind, making them susceptible to vulnerabilities that bad actors can exploit.

By establishing a comprehensive inventory of these systems, including their communication paths and dependencies, organizations can gain visibility into what needs protection and prioritize vulnerabilities. This principle also underscores the importance of segmenting OT systems from IT networks, ensuring that risks from the IT side don’t spill over into operational systems.

2. Implement Secure Configuration Practices

If your OT system configurations are insecure or out of date, it’s like leaving the front door of your house unlocked with the key under the mat. Secure configuration practices ensure that OT devices are set up to minimize exposure to attacks. This principle emphasizes the importance of hardening systems by removing default credentials, closing unnecessary ports, and disabling unused features or services.

Configurations should also be tested and validated regularly. Given that many OT systems can’t be easily updated due to uptime requirements, strong initial configuration and consistent monitoring can close potential security gaps without disrupting operations.

3. Reduce Your OT Attack Surface

The less exposed your OT systems are, the harder it is for malicious actors to find a foothold. This principle focuses on minimizing the attack surface by limiting network connectivity, disabling unnecessary features, and restricting direct access to critical OT systems.

It’s not just about reducing internet-facing components but also about using advanced measures like air-gapping, network segmentation, and zero-trust architectures to limit access to OT networks. This way, even if a breach occurs on the IT side, it won’t necessarily extend into the OT environment, preventing lateral movement.

4. Build a Resilient Architecture

Resilience means more than just defense; it’s about ensuring that OT systems can continue functioning during and after a cyber attack. Building resilience into OT architecture involves creating redundancies, maintaining robust backup systems, and ensuring that critical OT operations can survive even when under attack.

This principle encourages organizations to implement defense-in-depth strategies that layer security mechanisms throughout the system to provide multiple barriers against an attacker. With this, OT environments can remain functional, or at least recover quickly, if an attack does occur.

5. Prepare for and Manage Incidents

This principle stresses the importance of a proactive approach to incident response in OT environments. Given the high stakes of an OT attack, rapid response and recovery capabilities are essential. Organizations must have well-rehearsed incident response plans specifically tailored for OT systems, including roles and responsibilities, communication protocols, and system restoration processes.

Simulation exercises, threat hunting, and frequent drills are necessary to ensure teams are ready to act swiftly in case of a security incident. Preparation can make the difference between a controlled disruption and a cascading system failure.

6. Strengthen Your OT Supply Chain Security

Supply chain attacks are becoming more prevalent, and the OT world is no exception. Since OT environments rely heavily on third-party hardware, software, and services, this principle focuses on securing the entire supply chain. Organizations must vet suppliers thoroughly, ensuring that they meet cybersecurity standards and don’t introduce vulnerabilities into the OT environment.

Cybersecurity due diligence should be extended to all suppliers, from those providing physical devices to software vendors. Implementing security requirements in contracts and continuously monitoring the supply chain for risks can help organizations ensure that the trust they place in their partners doesn’t become a weakness.

The Importance of a Holistic Approach

What makes these six principles from the NSA stand out is their holistic nature. Rather than focusing solely on reactive measures or specific technology solutions, they promote a comprehensive, proactive approach to securing OT environments. In an era where cyber threats are becoming increasingly sophisticated and state-sponsored actors are targeting critical infrastructure, adhering to these principles can significantly reduce risk.

By understanding and controlling OT environments, implementing secure configurations, reducing the attack surface, building resilient architectures, preparing for incidents, and securing the supply chain, organizations can better safeguard their OT systems—and by extension, the critical services they deliver to society.

Conclusion

The NSA’s six principles for OT cybersecurity reflect a clear understanding of the modern threat landscape and the unique challenges that OT environments face. They offer a blueprint for organizations looking to protect their critical infrastructure in a way that is sustainable, scalable, and, most importantly, secure. As the lines between IT and OT continue to blur, adhering to these principles will help organizations strike that necessary balance between functionality and security in an increasingly connected world.