Security Analysis of Urban Railway Systems: The Need for a Cyber-Physical Perspective

Urban railway systems are increasingly relying on information and communications technologies (ICT). This evolution makes cybersecurity an important concern, in addition to the traditional focus on reliability, availability, maintainability and safety. In this paper, we examine two examples of cyberintensive systems in urban railway environments—a communications-based train control system, and a mobile app that provides transit information to commuters— and use them to study the challenges for conducting security analysis in this domain. We show the need for a cyber-physical perspective in order to understand the cross-domain attack/defense and the complicated physical consequence of cyber breaches. We present security analysis results from two different methods that are used in the safety and ICT security engineering domains respectively, and use them as concrete references to discuss the way to move forward.