Cybersecurity Considerations for Communication Based Train Control

The CENELEC TS 50701 is the first encompassing standard aiming at governing cybersecurity risk management processes within the railway industry. Although the technical maturity of this framework is undeniable, its application in practical projects is still an active field of discussion among practitioners, especially when dealing the communication-heavy subsystems. Among such subsystems, signalling is among the most critical ones. Both Communication-based Train Control (CBTC) and European Railway Traffic Management Systems (ERTMS) heavily rely on wireless communications for their operation. This paper describes two cybersecurity attack scenarios regarding wireless communications for CBTCs that can impact the safety of these systems using the lens of the framework provided by the novel CENELEC TS 50701. In doing so, we discuss the implications of using such guidance, especially concerning the different interpretations found in the literature regarding zoning communication systems, to assess and mitigate the cybersecurity risk and improve the posture of CBTC systems concerning the examined attacks. Experimental tests conducted in controlled laboratory environments and high-fidelity simulations have been conducted to support the cybersecurity analysis.