Just yesterday we heard about an Android 9.0 feature that would prevent idle background apps from accessing the camera. The move could prevent unauthorized use of the device’s camera to record video clips of the user’s environment.
Now, XDA has spotted another AOSP commit that introduces a similar functionality for Android’s microphone. According to the commit, Android P will prevent idle background apps from recording audio through the mic that creeps out users. It’ll monitor apps using their UID that assigned at the time of the installation. The term ‘idle’ is for the ‘Doze’ mode (not charging and screen off), where background apps’ access to the network and CPU-intensive services is restricted.
The implementation of the privacy feature involves a little bit of a trick that Android P plays on the apps. When an idle app requests mic access, empty data (a string of zeros in the byte array) is written to the file.
This way, a potentially malicious app hiding in the background won’t realize that the mic access has been revoked and it’s recording nothing but junk audio. Real mic data is provided to the app once it goes into an active state.
These new privacy measures would add to the background app limitations that arrived with Android O. Although, the changes are under-the-hood and don’t require any user interaction, having them on their device would give a sense of security to Android users. However, it’s unclear how it would affect legitimate Android apps which the user has granted permission to record audio.