Understanding the ERTMS Signalling System and Its Cybersecurity Risks

Evan Jones
Apr 29
3 min read

The future of rail is digital, but is it secure?

As railway systems across Europe modernise with digital signalling and wireless communication, cybersecurity is quickly becoming a core priority. One of the biggest drivers of this transformation is the European Rail Traffic Management Systems (ERTMS). While ERTMS promises safer and more efficient train operations, it also introduces new cyber risks that can impact passenger safety and service reliability. In this blog, we will break down the basics of ERTMS, how it’s different from ETCS, why cybersecurity matters, and what rail operators and CISOs should do to stay secure.

What is ERTMS?

European Rail Traffic Management Systems or ERTMS for short is a standardised signalling and control system being deployed across European railways. Its main goal is to replace the patchwork of national train control systems with a unified digital approach, allowing trains to move safely and efficiently across borders. ERTMS reduces reliance on traditional trackside signals by bringing key train data directly into the driver’s cab. This is the core of the ERTMS signalling systems, making railways smarter and safer.

What are the two main components of ERTMS? ERTMS includes:

ETCS (European Train Control System): A system that gives drivers real-time instructions (like speed limits and braking commands) on a screen in their cab, and automatically stops the train if it violates those instructions.
GSM-R (Global System for Mobile Communications - Railway): A special radio network that allows trains and control centres to talk to each other. It is based on an older mobile technology (2G) and is being phased out in favour of a more secure and modern system called FRMCS (Future Railway Mobile Communication System). The UK currently is supporting GSM-R for a number of years and therefore will fall behind Europe in the FRMCS implementation

What is the difference between ERTMS and ETCS?

Many people mix these terms up. Here’s the difference:

ETCS is a part of ERTMS. It’s the part that manages how trains move safely.
ERTMS is the full system. ERTMS includes ETCS, GSM-R (or FRMCS), and other communication protocols and operational rules.

In short: ERTMS = ETCS + Radio Communications + Traffic Management Control Systems

If you’re wondering about ERTMS meaning, it refers to both the technology and the operational framework that ensures digital train control and interoperability across Europe.

Why is ERTMS Cybersecurity Important?

As trains rely more on digital signals and wireless communications, they become vulnerable to the same types of cyberattacks that threaten other critical infrastructure. The more connected the system, the more potential points of entry for attackers.

Key risks include:

Unsecured wireless communication: The signals sent between trains and trackside equipment can be jammed or faked. For example, someone could send a fake stop command, causing a train to halt suddenly.
Outdated tech: GSM-R is based on 2G mobile tech from the 1990s. It wasn’t designed with modern cybersecurity in mind and leverages TETRA protocol which has known cryptographic weaknesses that can be exploited
Legacy Equipment: Older systems still in use may not have been built to defend against cyber threats and can act as weak links.
IT & OT convergence: More rail systems are connecting their control tech (Operational Technology or OT) with business systems (IT). This makes it easier for malware to jump from email servers or office laptops into signalling networks.

Real-world example of risks in ERTMS communication systems:

In 2023, Polish rail services were disrupted when attackers used simple radio signals to issue emergency stop commands to multiple trains. The attack worked because the stop signal was not protected with encryption or authentication, a clear example of why modern security is needed.

What should CISOs and rail operators do now?

Here are the most useful and actionable steps:

Use secure-by-design systems: Demand suppliers meet TS 50701 or equivalent standards. Avoid products that don’t prioritise security.
Protect critical communications: Encrypt GSM-R signals, monitor for jamming attempts, and prepare for FRMCS migration.
Segment networks: Keep IT (admin tools, email, etc) separate from OT (signalling and control).
Update and patch legacy tech: Replace or isolate vulnerable systems and keep software up to date.
Prepare for incidents: Have a response plan ready. Test it regularly and train staff across engineering, safety, and IT.
Collaborate and share: Join industry cyber forums and share threat info to improve response times.

In Summary:

ERTMS is the backbone of Europe’s digital railway transformation. It includes ETCS (train control) and GSM-R (communications), soon moving to FRMCS. But as digital adoption grows, so does the cyber risk.

Cyberattacks on ERTMS rail systems can cause service disruption, safety concerns, and loss of public trust. Securing the ERTMS signalling system is no longer optional. It is essential to keep railways safe, efficient and resilient.