This article is the fourth part of the Three Pillars of Enterprise IT Infrastructure series and addresses the continuity pillar in the context of critical infrastructure.

Power plants, water networks, transport systems, hospitals, financial institutions and public services... What these structures have in common is that when they stop, the impact does not stay within a single organization. A few hours of downtime on an e-commerce site means lost revenue; the same outage in a city's water management system becomes a public problem.

That is why the goal of security in critical infrastructure is not only to prevent attacks. The real goal is for the service to continue, whatever the attack or failure. The concept of cyber resilience expresses exactly that difference.

Cyber Security versus Cyber Resilience

Although the two terms are often used interchangeably, they answer different questions:

• Cyber security asks: "How do we keep the attacker out?"
• Cyber resilience asks: "When the attacker gets in, a system fails or a supplier goes offline, how do we keep the service running and how quickly do we recover?"

The Zero Trust architecture we covered in the previous article in this series proposed designing on the assumption of breach. Cyber resilience goes one step further: it accepts that the breach has happened and shifts its focus to containing the impact and restoring the service.

What Makes Critical Infrastructure Different?

Where IT Meets OT

A significant share of critical infrastructure relies on operational technology (OT) systems that control physical processes: SCADA systems, PLCs, field sensors. For many years these systems were designed to run isolated from the corporate network. Today, driven by remote monitoring, efficiency analysis and centralized management, they are increasingly connected to IT networks. That connection means a breach on the IT side can reach the physical world.

Long-Lived Systems

An office computer is replaced every few years; an industrial control system can stay in the field for decades. Systems that cannot be patched, whose vendor has ended support, or whose restart would halt production are not the exception in critical infrastructure but the norm. A resilience strategy cannot ignore that reality.

The Cost of Disruption

In a conventional IT environment, "disconnect the suspicious system immediately" can be the right reflex. In critical infrastructure, the same intervention can cause a bigger outage than the attack itself. Response decisions must therefore be planned in advance and designed together with the teams who understand how the system operates.

The Four Stages of Resilience

Cyber resilience is usually approached as a four-stage cycle. Each stage determines the success of the next.

1. Anticipate

Resilience cannot be planned without knowing which systems are critical, which service depends on which systems, and how long each service can tolerate an interruption. The output of this stage is not a technology list but a business impact analysis and an up-to-date asset inventory.

2. Withstand

This stage holds the building blocks that keep the essential service running during an attack or failure: redundant architecture, clear segmentation between IT and OT networks, independent power and communication for critical systems, and the ability to switch to manual operation when needed.

3. Recover

How long it will take to restore the service, and with how much data loss, must be decided in advance, not in the middle of a crisis. Immutable backups, tested recovery procedures and a disaster recovery centre form the foundation of this stage. A recovery plan that exists on paper but has never been tested rarely delivers the expected result in a real crisis.

4. Adapt

Every incident, whether a real attack or an exercise, is a source of data for improving the architecture. Post-incident reviews are not about finding someone to blame; they are about making sure the same weakness does not surface again.

Common Mistakes

• "We have an air gap, so we are safe." Truly isolated systems are rare today. Maintenance connections, removable media and supplier access often quietly eliminate the assumed isolation.
• Keeping backups on the same network. Ransomware now targets backups first. A backup sitting in the same privilege domain as the production environment offers no protection when the attack comes.
• Running exercises with the IT team only. In critical infrastructure, a cyber incident concerns operations, communications, legal and senior management at the same time. If these functions are absent from tabletop exercises, a coordination gap appears in the real crisis.
• Overlooking the supply chain. If the account of a supplier performing remote maintenance is less protected than the organization's own accounts, that is the attacker's easiest way in.

The Regulatory Dimension

The cyber resilience of critical infrastructure is no longer just a technical choice but a regulatory expectation. In Türkiye, the Information and Communication Security Guide published by the Presidency's Digital Transformation Office and the Cyber Security Law that entered into force in 2025 set the framework that public institutions and critical infrastructure operators must follow. In the European Union, the NIS2 Directive moves in a similar direction, bringing obligations with an expanded scope.

The common message of these regulations is the same: preventive controls alone are no longer considered sufficient; incident response, reporting and service continuity are also among the areas being audited.

How Resilient Is Your Organization? A Five-Question Test

• Do you have an up-to-date map showing which systems your critical services depend on?
• Are the crossings between your IT and OT networks defined, restricted and monitored?
• Are your backups protected so that they cannot be deleted even if an administrator account in production is compromised?
• Have you run a recovery test close to real-world conditions in the past year?
• Is it documented who makes which decision during a cyber incident?

If the answer to even one of these questions is "we are not sure", that is where the resilience plan needs to start.

The ORBISIS Approach: Dependencies First, Technology Second

At ORBISIS we begin critical infrastructure projects not with product selection but by uncovering service dependencies. Across our work, from the defence industry and transport to public institutions and large-scale archive projects, we design the network, data centre, backup and security layers around a single continuity goal. Our aim is not to promise that disruption will never happen, but to ensure that when it does, its impact is contained and recovery is predictable.

To assess your organization's level of cyber resilience together, explore our Cyber Security Solutions and Assessment Services pages, or get in touch with our expert team.