Android platform is a primary target for malware attacks from few years and during 2013, more than 79% of mobile operating malware threats are taking place on Android OS. The technique is not new, but infection from such app is first time in the wild. The variant dubbed MouaBad. p., is particularly sneaky and to avoid detection it waits to make its calls until a period of time after the screen turns off and the lock screen activates. The malware app works only on devices running Android version 3.1 or old and designed to mainly target Chinese-speaking users.
Source: https://thehackernews.com/2013/12/mouabad-android-malware-calling-to.html