Hackers could use smartwatches to eavesdrop on air-gapped computers via ultrasonic signals

A security specialist at Ben-Gurion University of the Negev has found evidence that it might be possible to infiltrate an air-gap computing system using a smartwatch. Mordechai Guri has published a paper outlining his ideas on the arXiv preprint server.

Air-gap computers or computing systems are those that have been physically removed from other networks, such as the internet, as a way to make them remotely hack-proof. The only way such a computer or system could be hacked would be to gain direct physical access or to have someone do it for them. In his paper, Guri suggests there may be another way—by using features of smartwatches.

Smartwatches, Guri notes, have all the features needed to listen for ultrasonic signals from an air-gapped computer, starting with a microphone. They also could be used for processing signals or for routing them to a speaker or a Wi-Fi device, which could broadcast them to a more sophisticated device.

He notes that testing of such a hacking approach has already shown that data can be broadcast over ultrasonic frequencies over a distance of approximately 6 meters at data rates of up to 50 bps. Such a scenario would involve a hacker gaining access to the computer and installing malware that would broadcast more easily decipherable information. Then, ultrasonic signals from the air-gapped computer could be captured by a nearby person wearing a smartwatch.

Such an approach might involve dormant malware that would only become active when a hacker is nearby. Uri even envisions a smartwatch being stolen from an employee, loaded with malware and then being clandestinely returned to the employee.

Guri acknowledges that using a smartwatch to hack an air-gap system would prove extremely difficult—a hacker would still have to gain proximity to a target computer or system. And they would have to do so without other people being aware of their presence—though it could possibly be done by a plant or a spy. In any case, it is likely such an attempt would only be made on extremely high-value targets, which would likely have many layers of other types of physical protection.

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