FOCUS: Frequency Based Detection of Covert Ultrasonic Signals

Abstract

Today's evolving and inventive attacks allow an adversary to embed tracking identifiers or malicious triggers in ultrasonic sound and covertly transmit them between devices without the users' knowledge. An adversary can exploit an electronic device by manipulating the microphone, gyroscope or speaker using ultrasonic sound. Almost all types of electronic devices are vulnerable to this type of attack. Indeed, some preventive measures are in place to counter ultrasonic invasion. However, they are primitive and often are not capable of detecting the attacks. To this end, we propose FOCUS: Frequency based detection of Covert Ultrasonic Signals. In particular, FOCUS displays a low-end, low-cost ultrasonic detection mechanism that can be employed anywhere. We validate FOCUS through two proof-of-concept (PoC) implementations utilizing Raspberry Pi and Arduino based hardware modules, respectively. The results demonstrate that FOCUS can detect ultrasonic sound and alert users of possible ultrasonic invasion.