A lot of smartphone apps can help you out if you let them access your phone's GPS. But even if you give permission, do you know everything they're doing with that information?

Some computer scientists wanted to find out. So they modified the Android mobile phone platform to tag all data apps sent from the phone. Then they randomly selected 30 of the most popular Android apps, choosing only ones that require access to the Internet and access to the phone's GPS, camera or microphone. And they played with them, all while tracking the data each app sent out.

Turns out 15—half the apps—sent the phone's location to third-party advertisers. Two apps did present user agreements—but they said nothing about sending that data. And a third of the apps revealed the phone's unique ID, sometimes along with the phone number and SIM card serial number. The findings will be presented at an upcoming USENIX Symposium. [William Enck et al., TaintDroid: An Information-Flow Tracking System for Realtime Privacy Monitoring on Smartphones]

The researchers won't say which apps committed the worst offenses. But there’s a good chance you could have some of the apps on your smartphone. And if one of them asks for your location, you can opt to have it mind its own business instead of yours.

—Christopher Intagliata

[The above text is an exact transcript of this podcast]