Sound waves could be used to hack into critical sensors used in a broad array of technologies including smartphones, automobiles, medical devices, and the Internet of Things, University of Michigan engineers have discovered. The engineering team used precisely tuned acoustic tones to deceive 15 different models of accelerometers into registering movement that never occurred. The approach served as a backdoor into the devices, enabling the researchers to control other aspects of the system. One proof-of-concept demonstration involved using a malicious music file to cause a Samsung Galaxy S5’s accelerometer to spell out the word “WALNUT” in a graph of its readings. The team developed two low-cost software defenses that could minimize the vulnerabilities, and they’ve alerted manufacturers to the issues.