In July 2025, Tom’s Hardware revealed a major vulnerability in the End‑of‑Train (EoT) and Head‑of‑Train (HoT) communication system used widely across American freight trains.
- What’s the system?
EoT/HoT modules, dating from the 1980s, transmit status telemetry and accept brake commands wirelessly between the train’s head & tail. - The flaw:
Rather than secure encryption, messages use only a simple BCH checksum—no authentication or encryption. With a cheap SDR (software-defined radio, under $500), attackers can spoof packets and remotely issue a brake command to the rear car. - Historical neglect:
The issue was first flagged in 2012 but dismissed as "theoretical" by the Association of American Railroads (AAR). Real‑world testing was blocked, and industry regulators lacked test tracks. Only a formal advisory from CISA in July 2025 forced action.
This vulnerability is now formally tracked as CVE‑2025‑1727, scoring 7.2 (CVSS v4) due to its low complexity and high impact.
Risks & Real‑World Impacts
This allows:
- Emergency brake triggers remotely, potentially halting trains unexpectedly in risky or sensitive areas.
- Operational disruptions, wasted time, collisions, or even hazardous chain‑reaction incidents.
- Widespread exploitation, affecting the estimated 75,000 EoT devices across North America—a replacement effort costing billions and potentially taking years
Response Timeline & Broader Mitigations
- AAR resistance until 2025: Only now are secure protocols (e.g., IEEE 802.16t) being adopted, with device replacements expected through 2027 or later.
- CISA advisory (July 10, 2025): Urges segmentation, VPN protection, network restrictions, and proactive risk assessments
Industry Reaction from 2016
A simultaneous corporate narrative crisis unfolded in 2016:
- Reports suggested that “smart train” systems were vulnerable to cyberattacks, potentially affecting control systems, signaling, or safety mechanisms.
- The National Railroad Safety Association publicly denied these claims, stating the rail industry was “secretive” and disputing any real cybersecurity weaknesses.
This evasive stance reflects a broader trend—facing mounting public pressure, rail authorities often downplayed concerns until independent investigations forced transparency.
Why This Threat Matters
Core Safety Systems Are at Risk
Brake control isn’t cosmetic—it’s essential. Interference can’t just upset schedules—it can cause:
- Collisions or derailments
- Engineered attacks triggering failures
- Psychological misuse (e.g., frequent stoppages) disrupting logistics
Legacy Tech Leaves Gaping Holes
Systems designed decades ago weren’t cyber‑conscious. Fixing them costs billions and takes years, leaving a long exploitable window.
Nationwide Impact
75,000+ EoT/HoT devices act as a single point of failure. Even a few successful attacks could have national-level disruption.
Precedent for ICS/OT Risk
This is emblematic of broader Industrial Control System weaknesses—exposed by CISA warnings—that plague critical infrastructure.
Recommendations for Rail Safety Improvement
- Immediate Network Isolation & Monitoring
Physically segment RF control channels, set up intrusion detection, and log/review commands. - Accelerated Device Upgrades
Move quickly to implement secure standards like IEEE 802.16t and apply crypto-heavy authentication. - Independent Security Testing
Open access to regulators and security researchers—without proprietary hurdles. - Regulatory Mandates
Set a timeline (e.g., replace by 2027) and impose fines for non-compliance. - Security-First Design
All future rail control upgrades must incorporate zero-trust cyber-secure principles from day one.
That a railroad braking system remained vulnerable to unauthenticated remote commands for over a decade highlights a sobering truth: when cyber‑security isn’t baked in, old systems can become modern threats. While CISA’s action and AAR’s response mark a shift, the journey to secure America’s rail infrastructure is only just beginning.
This episode should serve as a wake‑up call—not just for railroads, but for every operator of aging industrial systems: cyber‑resilience can’t wait until a crisis is undeniable. It must be built in now.