Recent developments in covert acoustical communications
The topic of covert acoustical communication in air has produced public attention, lately. In 2013, we presented the fact that infected drones (e.g. laptops) might form covert acoustical mesh networks in air, only utilizing the built-in speakers and microphones. In this article, we aim to present the current state of covert acoustical communication in air. We discuss future forms of covert acoustical mesh networks, we present an alternative audio signal that is improved in terms of stealthiness, and we provide considerations on the stealthiness of covert acoustical communication in air. In order to protect computing setups from malware utilizing covert acoustical communications, we present an analysis on detection and localization mechanisms for covert acoustical transmissions. Finally, we describe the implementation of an audio intrusion detection system that is designed for automatic analysis of acoustical emanations.