Critical Railway Braking Systems Open to Tampering

Researchers demonstrated that legacy balise-based train signalling systems (notably Spain's ASFA) can be spoofed or tampered with using inexpensive, improvised equipment to alter inductive signals and issue false speed/stop commands; the PoC raises serious safety risks for trains relying on outdated analog systems and suggests potential risks for digital ERTMS/ETCS as well, while noting remediation would be costly and politically sensitive. The findings will be presented at Black Hat Europe 2025.