As the finance sector is enfolded into the UK’s CNI, what does this mean for its ongoing digital journey?
The UK Government has recently broadened its definition of Critical National Infrastructure (CNI) to reflect the highly interconnected nature of the services citizens depend on, and the growing range of security threats they face. As such, fourteen distinct verticals now fall under the umbrella of CNI and so must now contend with the associated compliance obligations. Notably, the finance sector has now officially been granted this designation, which has huge implications for its ongoing digital journey and the long-term security and resilience of its critical data – a prime target for bad actors.
This shift is well-timed, as the Bank of England has recently concluded a multi-year project in collaboration with the NCSC, as highlighted in its 2025 report. Key to this has been the CBEST penetration assessment, which was launched in 2014 to help financial firms identify and mitigate weaknesses in their overall cyber security and resilience. Financial regulators began building on the data generated by these regular assessments in the second half of 2025, offering firms additional consultancy around ICT risk and cyber resilience. With the Government’s increased mandate and focus on the security of our nation’s CNI, financial organisations will have to accelerate a digital journey that’s already been picking up pace for a number of years now.
Banks, insurance companies, investment firms, and numerous other financial organisations have long been phasing out increasingly cumbersome legacy systems in favour of highly scalable, highly secure platforms that support the singular challenges involved in the transfer, storage, and management of financial data. This has not only helped maintain the integrity of this critical data in an increasingly complex, aggressive threat landscape, but also opened up new ways for clients to seamlessly access financial services across multiple channels.
Finance’s entry into the CNI space offers a unique opportunity to build on these early successes, exploring how the considerable advances made in the security of integrated IT/OT systems and Industrial Control Systems (ICSs) in recent years can be applied to the sector’s people, processes, and technology. Having worked with both Operators of Essential Services (OESs) and financial organisations in my role at the Exponential-e Group, I would argue that the following will prove essential in the months ahead, not only in terms of meeting firms’ immediate compliance obligations, but also ensuring the wider sector’s ongoing growth and public confidence can be maintained.
Treat physical systems with the same urgency as digital ones
One of the most notable aspects of CNI security is the need to accommodate the ongoing convergence of physical and digital systems, in order to ensure seamless flows of data can co-exist with ironclad security, with per-user access as standard and corporate security policies intelligently automated wherever possible. Firms’ overall security posture must therefore be based on a holistic approach that considers interconnected physical assets as much as data.
Ensure the very latest threat intelligence is acted upon
The NCSC has repeatedly emphasised the need for up-to-date threat intelligence to be implemented, moving beyond a reliance on standard toolsets, emphasising a proactive rather than reactive approach to security and resilience. While most organisations will have disaster recovery systems and processes in place, even the shortest period of downtime for CNI systems can have serious – potentially irreparable – consequences, as we have seen in various recent high-profile outages.
Security must be inherent in the design of all systems
The finance sector maintains highly distinctive working models that its systems have evolved to accommodate, but these cannot be allowed to create hidden security risks when non-traditional systems must be integrated. Instead, security must be factored into the design of all systems at the very outset – a ‘secure by design’ approach.
Phase out legacy infrastructure at the earliest opportunity
Related to the above point, many of the legacy systems financial organisations still maintain are no longer patched, which means ensuring their continued viability has created a considerable ‘technical debt’ – vulnerability and ongoing expense that could easily be reinvested elsewhere to great effect. These should be phased out in a considered manner that avoids any operational disruption and potential security risks, with their replacements offering the highest levels of scalability and agility.
Consider the integrity of the supply chain
Business is interconnected in ways that would have been inconceivable just ten years ago, and the same applies to CNI organisations, who frequently utilise global chains of suppliers for both physical and digital systems. Each of these interconnections represents a potential ‘backdoor’ to critical infrastructure that could be exploited, which means all potential suppliers must be regularly audited to ensure their own systems and processes meet the standards set out by current Government regulations around security and resilience.
There’s no doubt that there is much work to be done in the years ahead, but the finance sector as a whole has already demonstrated its growing readiness to embrace digital transformation, and recent advances in the security and resilience of CNI systems mean that the sector now enjoys a unique opportunity to adopt proven, powerful strategies for securing its critical systems. Not only will the help minimise the chances of another high-profile breach occurring, it will also help ensure the continued performance and availability of financial services to clients across the UK and – in turn – guarantee the sector’s long-term growth and stability.
##
For more information on these topics, our most recent report – Translating the new regulatory standards into a sustainable cyber strategy – is available for download here.
