The invention relates to an NFC device configured for receiving a request to perform a transaction. In response to receiving the request, sensor data from one or more sensors of the NFC device is fed into a first classifier. The sensor data comprises environment parameters of the NFC device. The first classifier determines if sensor data provided as input to the first classifier were sensed in a transaction-typical environment or in a transaction-atypical environment. In case the first classifier determines that the sensor data is indicative of a transaction-atypical environment, the first classifier blocks the transaction or requests a user to confirm the transaction and blocks the transaction until the confirmation is received.