Summary: Securing critical infrastructure in the OT domain is a pressing challenge as digitalization expands the attack surface. Three key solutions are proposed to address this challenge: OT asset discovery, network segmentation, and Zero Trust security. By embracing these strategies, OT professionals can protect critical assets, adapt to rapid changes, and fortify defenses against evolving cyber threats, ensuring the resilience and security of critical infrastructure in an increasingly connected world.

It is undeniable that critical national infrastructure is evolving at an unprecedented pace. The interconnectivity of OT/ICS systems has brought immense benefits and exposed them to new and evolving cyber threats. While OT professionals understand the importance of safeguarding these critical assets, they also face significant challenges in managing the expanding critical infrastructure attack surface.

The Cyber Debt Challenge of CNI Digital Transformation

As our critical infrastructure continues to embrace digitalization, the challenge is clear: how can we ensure the security and integrity of our OT systems while accommodating the rapid pace of interconnectivity? Although the solution lies in standardizing and controlling distributed data in a secure and consistent manner, the race to digitalization often leaves us with limited choices.

Distributed data is difficult to standardize and control in a consistent and secure way, while interconnectivity is happening too quickly. This often doesn’t leave enough time for technology to be properly updated and secured and for operating processes to be updated to ensure clear accountabilities, standards, and capabilities are embedded. Every time an old piece of equipment is plugged into a computer network, a new door is created for bad actors or malicious code to walk through, and these doors aren’t being spotted and are effectively boarded up.

This cyber debt opens up new threats. According to a report by Bridewell Consulting, although 78% of CNI organizations feel confident that their OT systems are protected from cyber threats, 86% of organizations report detecting a cyber incident affecting their OT/ICS environments in the last 12 months. One key factor behind the increased attack surface is that aging infrastructure and increased connectivity introduce new risks. Over three-quarters (79%) of organizations’ main OT systems are over five years old, and over a third (34%) are over 10 years old, while the majority (84%) of OT/ICS environments are accessible from corporate networks.

Digitalization can bring a significant competitive advantage and promise ROI savings to Critical National Infrastructure (CNI) industries. However, decision-makers often do not factor in the cost of upgrading technology, processes, and capabilities to ensure security by design and secure operations into the total cost of ownership. Regarding critical infrastructure security, the roles responsible for ensuring secure operations often have different, conflicting priorities. Safety, quality, ROI, and speed are often prioritized over security, leading to potential vulnerabilities and risks.

Four Steps and Three Solutions for CNI Resilience

Organizations are starting to realize that the operational technology supporting critical infrastructure is much larger and more valuable than their traditional corporate IT infrastructure. Due to the increased risk posed to these assets, decision-makers must develop and implement a strong security plan for their OT.

This plan should include the following four fundamental steps:

  1. Adopt a risk-based approach and an agile mindset.
  2. Incorporate a risk framework and security solutions that can provide the biggest ROI in risk reduction.
  3. Maintain a balance between digital transformation speed and security.
  4. Keep a close eye on mergers, acquisitions, and supply chains.

Additionally, the security plan must emphasize implementing three core security solutions.

Solution 1: OT Asset Discovery

OT asset discovery is the foundation of any robust cybersecurity strategy. To effectively manage the expanding critical infrastructure attack surface, it is imperative that you know your assets inside out. Asset discovery involves identifying and cataloging all OT assets, from sensors and controllers to industrial machines and network devices.

OT asset discovery is a game-changer for many reasons, including:

  1. Visibility: You cannot protect what you cannot see. Asset discovery provides complete visibility into your OT environment, helping you identify vulnerabilities and potential attack points.
  2. Risk Assessment: With a comprehensive inventory of assets, you can conduct thorough risk assessments, prioritize vulnerabilities, and allocate resources efficiently.
  3. Change Management: As your infrastructure evolves, asset discovery ensures that new devices and systems are properly documented, allowing for more effective change management.
  4. Incident Response: In the event of a cyber incident, knowing your assets enables quicker and more precise incident response, reducing downtime and potential damage.

Solution 2: Network Segmentation

Network segmentation is another critical strategy for managing the expanding attack surface of critical infrastructure. This approach involves dividing your network into isolated segments, each with its own security measures and access controls. By implementing network segmentation, you create barriers that limit the lateral movement of attackers within your infrastructure.

Network segmentation is essential for the following reasons:

  1. Containment: If a breach occurs, segmentation limits the attacker’s ability to move freely throughout the network, preventing them from accessing critical assets.
  2. Least Privilege Access: With network segmentation, you can enforce the principle of least privilege, ensuring that users and devices only have access to the resources they need for their specific tasks.
  3. Reduced Attack Surface: Segmentation reduces the attack surface within each network segment, making it more challenging for attackers to find and exploit vulnerabilities.
  4. Compliance: Many industry regulations and standards, such as NIST and IEC 62443, recommend or require network segmentation as a security best practice.

Solution 3: Zero Trust Security

Zero Trust security is a paradigm shift in cybersecurity that assumes no trust, even within your network. This approach aligns perfectly with the challenge of securing an expanding critical infrastructure attack surface. Every user and device is considered untrusted until they can prove their identity and meet security requirements.

Adopting a Zero Trust approach is a game-changer for CNI cybersecurity because it ensures:

  1. Continuous Authentication: Zero Trust continuously verifies the identity and security posture of users and devices, ensuring that only authorized entities have access to critical resources.
  2. Micro-Segmentation: Zero Trust complements network segmentation by implementing micro-segmentation, where security policies are applied at the granular level, enhancing security within network segments.
  3. Adaptive Access Control: Access permissions are dynamically adjusted based on user behavior and the risk level associated with each access request, enhancing security without sacrificing productivity.
  4. Data Protection: Zero Trust emphasizes data protection, ensuring that sensitive information is encrypted, monitored, and protected from unauthorized access, even within trusted zones.


Security professionals working in the OT domain are responsible for securing the critical infrastructure that underpins our society. While the challenges of managing an expanding attack surface are undeniable, the solutions are within reach. OT asset discovery, network segmentation, and Zero Trust security are not mere buzzwords but practical strategies that can fortify our defenses against evolving cyber threats.

The path forward in today’s digital world is clear: embrace these strategies, invest in the necessary technology and expertise, and ensure that our critical infrastructure remains resilient and secure. By doing so, we can continue to harness digitalization’s benefits without compromising our OT systems’ safety and reliability. The future of critical infrastructure security is in our hands, and it begins with proactive and strategic cybersecurity measures.

ITEGRITI has deep experience across critical infrastructure cybersecurity programs, compliance, risk, and audit.  Contact us today to learn how we can leverage this experience to help you accomplish your cybersecurity goals.

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