NFC Payments The Art of Relay & Replay

### Exploiting Near-Field Communication Payment Systems At 00:00, hardware security researcher Salvador Mendoza presents offensive research targeting Near-Field Communication (NFC) payment architectures, demonstrating practical relay and replay attacks against mobile wallets and contactless cards.

### Mobile Payment Tokenization Mechanics At 05:01, Mendoza analyzes the tokenization process used by mobile payment platforms (such as Apple Pay and Samsung Pay). While mobile systems avoid transmitting primary account numbers (PANs) by generating dynamic cryptograms and transient tokens, underlying protocol flaws can leave these tokens vulnerable to manipulation.

### Replay Vulnerabilities and Token Lifetime Exploitation At 10:02, the speaker demonstrates replay attack vectors. Mendoza exposes timing flaws where payment tokens remain valid across multiple transaction windows or can be pre-computed, harvested wirelessly, and replayed hours later at unattended Point of Sale (PoS) terminals.

### Custom Hardware Prototyping and Miniaturization At 15:00, Mendoza showcases custom offensive hardware designs. Utilizing SPI/I2C communication modules, ultra-thin inductive coils, and microcontrollers, he demonstrates building miniature interception devices that fit covertly into standard payment reader bezels or smartphone cases.

### Real-Time Wireless Relay Attacks and Defensive Mitigations Concluding between 20:02 and 25:01, the presentation explores real-time relay attacks. By streaming harvested NFC transaction frames over long-distance Wi-Fi or cellular connections to a proxy device at a remote payment terminal, an attacker can charge a victim's card in real time. Mendoza concludes by recommending strict PoS response timeouts and geofenced transaction limits to defeat relay techniques.

(AI summary — Gemini Flash)