The Stagefright bug is a very dangerous exploit which has been taking over control of Android phones and other devices since last summer.
Most of the Android devices currently in use are affected by this exploit. Although Google released a patch for the Stagefright Bug within days of its discovery, many phone providers have been slow to roll out the patch to their customers.
The Stagefright bug vulnerability affects all phones from Android version 2.2 through 5.1. Patches became available in October 2015, so if your phone received an updated version of Android since that date, you may be safe.
The security researcher who initially discovered this vulnerability has released a free App (available from the Google Play Store) which will check your device and report whether it is vulnerable to this bug.
You can use this link to access and install the app.

