Sounds played over off-the-shelf or embedded speakers often require a reboot.Attackers can cause potentially harmful hard drive and operating system crashes by playing sounds over low-cost speakers embedded in computers or sold in stores, a team of researchers demonstrated last week.
The attacks use sonic and ultrasonic sounds to disrupt magnetic HDDs as they read or write data. The researchers showed how the technique could stop some video-surveillance systems from recording live streams. Just 12 seconds of specially designed acoustic interference was all it took to cause video loss in a 720p system made by Ezviz. Sounds that lasted for 105 seconds or more caused the stock Western Digital 3.5 HDD in the device to stop recording altogether until it was rebooted.
The device uses flash storage to house its firmware, but by default it uses a magnetic HDD to store the large quantities of video it records. The attack used a speaker hanging from a ceiling that rested about four inches above the surveillance system’s HDD. The researchers didn’t remove the casing or otherwise tamper with the surveillance system.