Relayattacker

Relayattacker refers to an actor who carries out relay attacks by intercepting and forwarding communications between two parties, creating the appearance of a direct, close-range interaction. The attacker typically uses at least two devices to relay signals: one placed near the victim's credential (such as a key fob or access card) and another near the legitimate reader or terminal. This bridging can allow an unauthorized party to gain access or conduct a transaction as if the credential were nearby.

Common targets include contactless payment cards, RFID access badges, and keyless entry systems for vehicles or buildings. By relaying messages, the attacker can enable unauthorized access or fraudulent transactions without the victim’s knowledge, sometimes by extending the effective range of a credential while remaining inconspicuous.

Relay attacks are a form of man-in-the-middle attack that preserves the content of the exchanged messages while disguising the real distance between parties. Attackers may seek to minimize detection by keeping latency low and maintaining the normal protocol flow; some threats also exploit timing gaps to evade simple proximity checks.

Defenses focus on stronger proximity assurances and cryptographic protections, including distance-bounding protocols, mutual authentication, and liveness checks. Secure key management and robust hardware security features reduce vulnerability, as do physical countermeasures such as shielding and isolating credentials. User awareness about suspicious readers and unusual access attempts also helps mitigate risk.

See also: relay attack, man-in-the-middle, proximity card, RFID, near-field communication.