A recent malware discovered by the AVG mobile security team could allow hackers spy on mobile devices even though they are switched off. According to AVG, the malware hijacks the shutting down process of your mobile, so when the user turns the power off button to shut down their mobile, it doesn’t really shut down.

After pressing the power button, you will see the real shutdown animation, and the phone appears off. Although the screen is black, it is still on.

While the phone is in this state, the malware can make outgoing calls, take pictures and perform many other tasks without notifying the user, the researchers added.

According to AVG, the malware takes advantage of the shut down process when you press the power off button on your Android device. Actually it acts exactly before you select an option in the dialog that appears after a long puch of the shut down button - actions such as power off, mute or airplane mode.

Since the malware has already applied and acquired for a root permission, it malware will inject the special process and when you press the power button, a fake dialog will pop up. And if you select power off option, it will display a fake shut down animation, leaving the power on but the screen off.

Luckily, this malware is detectbable by some antivirus programs. But next time if you want to make sure your mobile is really off, take the battery out :)