Watermarking Based Sensor Attack Detection in Home Automation Systems

We present a watermarking scheme for sensor data, which accurately detects sensor voltage manipulation attacks. Due to a low complexity implementation running locally on a microcontroller, the proposed technique is well suited for home automation systems but also IoT systems where lightweight sensor nodes with restricted communication capabilities are commonly applied. The watermarking technique is based on modulating the sensor supply voltage, which embeds the watermark signal into the sensor output voltage. Hence, invasive voltage tampering attempts including ADC grounding and voltage injection attacks can be efficiently detected. According to the performed characterization results, our method is able to distinguish normal operation and an attack condition with approx. 98% accuracy for the entire ADC input voltage range. In a real-world demonstration involving a thermistor based temperature sensor all attack attempts were successfully detected.