The UK’s critical national infrastructure (CNI) underpins everything from utilities, finance, emergency services, defence, transport and more. As digital transformation accelerates, these sectors are increasingly under threat from cyber attacks. The consequences of a compromise can account significant economic impacts, in addition to social and security concerns. Attacks can have a destructive impact, causing severe, long-lasting, and widespread damage to critical infrastructure. For CISOs and board directors, the question is no longer whether CNI will be targeted, but how prepared your organisation is to withstand and recover from an attack.
Critical infrastructure: What’s at stake?
Critical national infrastructure forms the backbone of the UK, providing critical services that underpin national security and public health. From energy, water, transportation, healthcare, telecommunications, and emergency services, CNI provides essential services across multiple sectors.
From assets, facilities, systems and networks, to the frontline employees who are responsible for them, all are fundamental to the delivery of services that the nation depends on. Any compromise, whether through cyber attacks, natural hazards, or operational failures, can have a major detrimental impact. The consequences may include significant loss of life, disruption to emergency and rescue services, economic instability, and far-reaching social impacts. Picture it, an inbound attack on the National Grid or an infiltration of Thames Water’s supply system could cause mayhem right across the nation. This would not only impact the daily life of citizens but also threaten the safety of frontline workers and individuals.
Given the significant impact that disruptions can have, it is vital for cyber risk owners, including government departments, CNI organisations, and appropriately cleared government officials, to work collaboratively to identify, assess, and mitigate risks. This unified approach as well as a robust third-party risk management strategy are essential for maintaining a secure environment and ensuring the UK’s national infrastructure remains operational.
The complexity of the UK’s critical infrastructure is increasing, with interdependencies mapped across sectors and systems. The integration of artificial intelligence and advanced technologies offers new tools to enhance operational efficiency and resilience, but also introduces new risks that must be managed carefully. As climate change, state actors, and other new threats emerge, the need for robust cyber resilience and proactive investment in security measures has never been greater.
Protecting the UK’s critical national infrastructure is not just about compliance, it’s about safeguarding the essential services that support life, the economy, and national security. By identifying key questions, investing in future-proof solutions, and fostering collaboration across industry and government, we can ensure that the UK’s CNI remains secure, resilient, and capable of withstanding whatever challenges lie ahead.
The evolving threat landscape for organisations
In August 2025 we saw Johnson Controls disclosing a critical vulnerability affecting FX80 and FX90 supervisory controllers. These devices are widely used in building automation and facility management across many critical sectors. The flaw stemmed from a dependency on a vulnerable third-party component which could allow remote attackers to compromise configuration files and manipulate device settings.
While no attacks were reported during this period, Johnson Controls did suffer a ransomware attack back in 2023 by Dark Angels Group whereby data was stolen, including personal information, building floor plans, and security system details. Given that CISA issued advisories for operational technology (OT) vulnerabilities this year, it presents an ongoing risk that attackers will target these systems again going forward.
Outside of OT systems, attackers are exploiting gaps in outdated SCADA systems and slow patching cycles, often with devastating consequences. Threat actors and ransomware gangs are increasingly focusing on CNI because successful attacks create mass disruption and hugely impact the general public. Alongside this, there is the added intelligence gathering exercise that attackers can benefit from when they penetrate systems and gain access to data, rolling out ransomware threats leading to monetisation requests.
Boards must recognise that these threats are not hypothetical. They are active, sophisticated, and often well-funded. A single breach can lead to operational shutdowns, reputational damage, and regulatory penalties.
Engaging the board: Building resilience starts from the top
With our deep sector experience in CNI and OT for over 15 years, including all of the Nuclear Reactors in the UK, the challenge has always been more complex than in a purely IT environment. You must bridge IT and OT, deal with legacy systems, ensure uptime, and satisfy regulatory requirements.
One of the key strategies for CISOs is getting the attention from and collective buy-in from the board. It’s key that cyber and OT risk is translated into a language that the board truly understands. What are the potential risks to the business, what will the impact be if a service is disrupted and the knock-on effect on public safety, reputation and trust? Often, the visibility of security risk presented back to the board is limited. Fragmented reporting means understanding the true risk becomes unclear, leading to a decrease in cyber posture. By mapping the risks to the impact on business outcomes will better engage board directors, allowing a more joined up approach of quantifying top risks, control gaps, trend indicators and required decisions.
How CISOs can protect CNI and regulatory guidance
Deploying OT-aware intrusion detection and anomaly detection systems are key for not only identifying and containing threats before entry but also protecting vital infrastructure and preventing downtime in the event of an attack. For highly regulated
and CNI environments, having robust incident response and resilience planning protocol in place is essential for organisations.
Developing and testing tabletop exercises geared to an OT-specific incident response scenario will ensure key leaders within the organisation are fully prepared in the event that a real-world attack strikes where fallback systems and capabilities can be established. This also ensures defences are as robust as they can be and if not, systems alterations can be made to strengthen and enhance the cyber posture.
Most of the UK’s critical national infrastructure is in private hands, so the country’s resilience relies heavily on how well those organisations manage cyber risk going forward. Sectors such as finance have operated under tight regulatory scrutiny for years, while others have leaned more on guidance than enforcement. The Cyber Security and Resilience Bill changes that. It sets clear, enforceable expectations across industries and gives regulators the ability to hold private operators to account. So, for CISOs, this means that regulatory requirements have to be built into core security strategies to protect CNI, not addressed after the fact.
Cyber resilience for CNI is not optional, it’s imperative and demands board-level attention. By bridging IT and OT, embedding resilience into governance, and investing in people and processes, organisations can protect the systems that keep the UK running. The threats are real, but so are the opportunities to lead. Boards that act decisively will not only safeguard their operations and truly understand their risk posture, they will also strengthen trust with the customers and the citizens they serve.
