BY SySTem

Interlocking Systems at the Core of Rail Safety

Interlocking systems (IXL) form the foundation of rail safety, controlling routes, signals, and switch positions to prevent conflicting movements. Cybersecurity for interlockings must protect integrity and correctness without altering logic, timing, or certified behavior.

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Challenges

The Main Challenges in Securing Interlocking Systems

Interlockings rely on logic that must not change

Safety depends on strict rule sets and predictable execution, validated SIL 4 (Safety Integrity Level 4). Any unintended modification, delay, or interference, whether malicious or accidental, can undermine trust in the system.

Technology lifecycles span decades

Interlocking environments frequently include legacy hardware, proprietary protocols, and interfaces added incrementally over time. Limited native security controls and sparse documentation make it difficult to understand how systems are interconnected or how changes affect overall behavior.

Access is infrequent but high-impact

Configuration changes, maintenance access, and upgrades occur rarely, but when they do, the risk is significant. Security teams must be able to verify that any changes were intentional, authorized, and limited in scope, without introducing intrusive monitoring.

OUR Solution

How CylusOne Secures Interlocking Systems

Non-Intrusive Visibility Into Communications

CylusOne secures interlocking systems by passively observing signaling and control communications between the IXL, object controllers, LEUs, points, signals, and track sensors - without interacting with certified control logic. It establishes a behavioral baseline that reflects normal route-setting, signaling commands, and system interactions as they occur in live operation.

Detecting Unintended Change in Interlocking Behavior

CylusOne helps teams identify deviations that could indicate misconfiguration, unintended change, or cyber risk. Focusing on communication patterns and system relationships rather than internal logic enables investigation of anomalies without touching the interlocking itself or affecting deterministic behavior.

Supporting Safe Assurance of Interlocking Integrity

CylusOne supports rail-safe assurance for interlocking environments by providing context around access events, configuration activity, and authorized engineering sessions. This allows security and engineering teams to confirm system integrity, assess impact, and respond carefully, preserving safety guarantees while improving confidence in one of the most critical components of the rail network.

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