This may have happened to you. You idly browse a pair of shoes online one morning, and for the rest of the week, those shoes follow you across the Internet, appearing in adverts across the websites you visit.
But what if those ads could pop out of your browser and hound you across different devices? This is the power of ultrasound technology, says Vasilios Mavroudis at University College London – and it offers a whole new way in for hacking attacks and privacy invasions. He and his colleagues will spell out their concerns at next week’s Black Hat cybersecurity conference in London.
So far, this kind of ultrasound technology has mainly been used as a way for marketers and advertisers to identify and track people exposed to their messages, like a cross-device cookie. High-frequency audio “beacons” are embedded into TV commercials or browser ads. These sounds, which are inaudible to the human ear, can be picked up by any nearby device that has a microphone and can then activate certain functions on that device. But the technology has many more applications. Some shopping reward apps, such as Shopkick, already use it to let retailers push department or aisle-specific ads and promotions to customers’ phones as they shop.
“It doesn’t require any special technology,” Mavroudis says. “If you’re a supermarket, all you need are regular speakers.”