This paper was written by/on behalf of the IRSE's International Technical Committee (ITC). It was published in IRSE NEWS September 2017.

Railway signalling systems cannot be considered as self-contained any longer and new kinds of threats have to be considered and taken care of, related to the fact that the railway signalling systems are more and more
wide-spread, highly integrated and communication-based. Based on these core aspects, additional vulnerabilities have to be considered related to aspects as increasing integration with non-signalling subsystems and aging technology in legacy systems which have been put into operation long before the current threat level has evolved.

All these so-called “cyber threats” are requiring new measures and efforts in order to ensure the integrity and safety of the railway system – and they cannot be considered to be taken by one of the business partners alone. In the scope of this article, security and safety are referred to based on the following definitions:

• Security: Comprises all measures that are taken to protect a place or an item against espionage or sabotage, crime, attack or escape, or to ensure that only people with permission enter or leave it.
• Safety: Comprises all measures that are taken to ensure that travel and traffic on rail is being performed without accidents causing injuries or fatalities.

Within a railway command and control system the approach to cybersecurity has to be a system-oriented activity, as part of the overall ‘system engineering’ approach and covering the whole life-span of the system. Considering only single products will not be sufficient. Products and subsystems will have to be hardened
for security nonetheless.

The architecture has to incorporate measures and capabilities to implement security, thus the rail control system needs to be implemented according to a security architecture which is aligned with the safety architecture and overall architecture: “cybersecure by design” is one indispensable prerequisite to achieve security of the whole system. In addition, process and social aspects need to be covered in order to ensure secure operation, maintenance and use of the system throughout its lifecycle.

The paper looks at the standards for cybersecurity, the legislative frameworks, and the key principles for good cyber-security, adopting a whole-life approach.

Following a comprehensive scheme based on the NIST approach and supporting signalling system network standardisation initiatives can help the different actors to align their views and approaches to cybersecurity in order to collaborate effectively.