A major flaw in Android software allows an attacker to take complete control of a device by simply sending a specifically crafted media text message. The flaw was first reported by Zimperium zLabs VP of Platform Research and Exploitation, Joshua J. Drake – See more at: http://blog.zimperium.com/experts-found-a-unicorn-in-the-heart-of-android/#sthash.92fOeK4Q.dpuf
To kitigate the threat until an Android device receives a patch, go to Hangouts, select the menu in the upper left and select Settings. SElect the SMS settings, scroll down until you see "Auto retrieve SMS and UNCHECK that box.