Android Apps may be eavesdropping: Ultrasonic tracking for advertising purposes

Android apps are eavesdropping

Do you value your privacy? It’s almost impossible to keep your business private if you use Google. Google really does knows everything about its users. They know all about you from your Internet history, to searches carried out verbally. But now Android apps are also collecting information about you too – by eavesdropping.

Over 230 apps support something called ultrasound tracking. But what exactly is it? What do the listening apps do? What is ultrasound tracking ? And what does this mean for you? Read on to find out.

High-quality speakers and microphones are installed in every smartphone. These are versatile and sometimes can be misused. For example, Google can be helpful if you use it’s language assistant, see our blog post, Google Voice Assistant . But what happens when the listener is unauthorised?

Android Apps that are eavesdropping

There are hundreds of apps that potentially could be eavesdropping on you. The Android apps’ interception attack works through ultrasound tracking. They emit signals with a frequency range of  between 18 and 20 kHz. This frequency range is not perceptible to the human ear. Those apps which are equipped with it, however, receive signals from the user. The companies then use this information for advertising purposes. For example, a restaurant chain could tap smartphones around the area to see if a user is nearby. Researchers at the Braunschweig University of Technology in Germany have summarised the results and presented them in a study.

Ultrasonic tracking for advertising purposes

The purpose of ultrasonic tracking is mainly for advertising. The affected apps rely on a program extension from the provider Silverpush, which listens to the ultrasound signals. If the sounds then go unnoticed, for example on TV or via the sound system of a department store, the apps connect the location or the television habits of the user with his profile. Up to now, the analysts from Braunschweig have found the main users originate mainly from Southeast Asia and the USA where there are well-known corporations like McDonald’s and KrispyKreme. So it is only a matter of time until the listening apps begins to listen to us too. After all, the ultrasound transmitters suitable for the applications were found in 4 of the 35 shops examined in two European cities.

Eavesdropping without user consent

The worrying part of this deceitful eavesdropping attack is that it happens without user consent. These spying apps are able to collect information about apps used, places and websites visited. Therefore, the researchers rate ultrasound tracking as a “threat to privacy” as it allows “unintended tracking of sites, behaviour and devices”. In addition, advertisers can identify your media usage by recording the ultrasound signals and then personalise the advertising. “A villain could even assign precise sensitive content such as political documentaries or adult movies to a particular person – even at different locations,” the researchers explain.

What can you do about the eavesdropping apps?

But how can you protect yourself from a listening app? It’s quite easy to safeguard yourself. You just need to check your app permissions in the settings. For example, games or news apps should not have access to the microphone. In case of doubt, just delete such apps and look for alternatives that do not require microphone permission. For more information about ultrasound tracking, visit the following articles: Researchers Find 234 Android Apps That Track You , examples of how smartphones are listening and ultrasound advertising tracking.