Smartphone privacy, apps spy on you with ultrasound

It sounds like science fiction technology, but a study has revealed the possibility of devices being tracked using ultrasonic signals

Device tracking is a serious threat to users' privacy as it allows them to spy on their habits and activities. A recent technique takes advantage of ultrasonic audio transmitters and tracks them using the microphone of portable devices. The technology is still in its infancy, but is growing in popularity.

The study comes from a team of German researchers who analyzed cell phone tracking using ultrasounds that emit frequencies at 20 kHz, thus, higher than those audible by a human ear. But some smartphone applications are able to pick them up. And some companies have admitted to already using this technology, but in a form that is still not very invasive. How? Through videos and billboards, web pages or stores that emit high-frequency sounds that apps, with access to the phone's microphone, are able to pick up and create a profile on what you've seen, where, and in some cases, even the sites you've visited.

Peddled by Ultrasound

Using this ad-tracking technology allows advertising companies to link media consumption habits to a person's identity by collecting ultrasound frequencies from websites and radio and TV broadcasts. But that's not all. Ultrasonic frequencies can also be used to track locations, behaviors, and purchasing habits across multiple devices-all information that allows the advertiser to serve specific, personalized ads based on where you've been.

Listening Apps

Researchers, starting with an analysis of 1.3 million Android apps, discovered that 234 of them contained a code to activate the feature to listen to ultrasonic frequencies, of course, without the user's knowledge. It is not so easy to know if an app is equipped with this ultrasonic technology. The researchers' advice is dictated by common sense: always check the permissions required by apps. If there is no reason for a program, such as a game or news app, to access the phone's microphone, disable it. The threat of ultrasonic monitoring is, at the moment, fairly circumscribed, not least because there are technologies that make it much easier to "stalk" a device.