relayaanvallen

Relayaanvallen, commonly referred to as relay attacks, are a class of security exploits in which an attacker relays communications between two devices that believe they are speaking directly to each other. The attacker’s goal is to create the illusion that the distant device is in close proximity, enabling actions that would normally require contact or short range.

In a typical relay attack, two or more attackers cooperate. One agent stays near the victim device (for example, a key fob, a payment card, or a door badge) and the other near the service or reader (such as a car, a payment terminal, or an access control reader). Messages are forwarded between the two locations with minimal delay, making the reader believe the victim device is nearby and authenticated. This can open doors, authorize payments, or enable access that would normally be refused due to distance.

Common targets include contactless payment cards, smart keys for vehicles, access-control badges, and some NFC-enabled mobile devices. Real-world demonstrations have shown how relay attacks can enable car theft, unauthorized building access, or counterfeit payments by exploiting the trust placed in proximity-based authentication.

Defenses focus on proving proximity and preventing relay. Techniques include distance-bounding protocols, stronger mutual authentication, and cryptographic challenges that bound the allowable response time. Physical measures such as shielding or removing near-field devices when not in use, as well as user-initiated actions (multi-factor authentication, secondary confirmations), can also reduce risk.

Relayaanvallen have been a subject of extensive research since the early 2000s, particularly in the contexts of RFID, NFC, and IoT security. They remain a practical concern for systems relying on perceived short range for security.