A Security researcher John Gordon found an easy way to bypass the lockscreen of Android 5.0 and 5.1 (Build LMY48M) and get access to the device without knowing its password. This hack requires just patience and few easy steps which any one can follow. Now the bug has been fixed in the recent Android version. But there are so many devices which are still running in vulnerable version.
Process to bypass the lockscreen is simple. Open the emergency call screen and type around 10 characters. Double tap to highlight texts, copy and then paste and the end of existing characters. Follow the same steps until it stops selecting the existing characters. Now open camera app which you can access even if phone is locked. Open the notification bar and try to access the settings page. It will prompt password. Now again follow the same copy paste work which you did on the emergency call screen. Ultimate goal is to make the copied string as large as you can. Now come back to camera app, try to tap on screen and do other things. Wait for few minutes until the app crashes and you get access to the device.
In recent version of Android Lollipop, this vulnerability has been fixed. Number of users running vulnerable version of Android are low, so it affects only very small portion of Android users.
You can watch this video to know how the hacker bypassed the lockscreen.
