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Skype for Android Lockscreen Bypass

Tested with Skype version 3.2.0.6673 (released 1st July 2013) on various Android devices (Sony Xperia Z, Samsung Galaxy Note 2, Huawei Premia 4G The Skype for Android application appears to have a bug which permits the Android inbuilt lockscreen (ie. pattern, PIN, password) to be bypassed relatively easily, if the device is logged into Skype, and the "attacker" is able to call the "victim" on Skype. This can be reproduced as follows with 2 Skype accounts, and 2 separate devices to use with Skype. The target phone is presumed to have an Android lockscreen configured and in use, and to be locked during the test. 1. Initiate a Skype call to the target device, which will cause it to wake, ring, and display a prompt on the screen to answer or reject the call 2. Accept the call from the target device using the green answer button on the screen 3. End the call from the initiating device (ie. the device used to call the target phone) 4. The target device will end the call, and should display the lockscreen. 5. Turn off the screen of the target device using the power key, and turn it on again 6. The lockscreen will now be bypassed. It will remain bypassed until the device is rebooted Similar to (ironically enough): http://arstechnica.com/security/2013/04/crital-app-flaw-bypasses-screen-lock-on-up-to-100-million-android-phones/. Seems that internet based calling apps might well be "unlucky". Thanks to Emilio López for originally bringing this to my attention

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