NFC Relay Attack

Near-field communication (NFC) is designed for very short-range communication — typically a few centimetres — used in contactless payments, access cards, and transit tickets. An NFC relay attack defeats this range limitation by using two devices working in tandem: one device positioned close to the victim's wallet or card (the 'reader' end), and another near a payment terminal the attacker wants to transact at (the 'emulator' end). The two devices communicate via the internet or Bluetooth, effectively relaying the NFC signals across arbitrary distances.

In a payment relay scenario, the attacker's emulator presents itself to a checkout terminal as if it were the victim's card, while the reader silently harvests the NFC signal from the victim standing nearby in a queue or on public transport. The attack is particularly concerning because contactless payments under a threshold do not require a PIN, making them easier to relay.

Mitigations include using RFID-blocking wallets or card sleeves, enabling transaction notifications on bank accounts, and relying on device-based mobile payments (which include cryptographic tokens tied to the specific device) rather than physical cards for contactless transactions.