It’s surprisingly easy for anyone to buy ads that track location and app usage, study says

Researchers at the University of Washington have found a way to track a person’s location and app use through serving ads on mobile apps.

The result opens the door for significant privacy invasions through the app-based advertising system. The researchers obtained the information by purchasing a series of ads targeted to specific locations and apps, then checking which mobile subscribers fit the targeting. In experiments conducted on Android devices, the team was able to pinpoint a person’s location within eight meters through a targeted ad. They tested ads on 10 different apps, including Grindr, Imgur, Words with Friends, and Talkatone, all using widely available ad networks. By serving ad content to a user’s apps, the ad buyers could learn what apps the user has installed. That information could be sensitive, revealing a user’s sexual orientation or religious affiliation. Researchers could also find out when a user went to a specific place. After targeting ads to a specific location, the ad network would notify them within 10 minutes of when the user arrived.