A new security bypass vulnerability has been identified in Android 4.3 and prior versions. An attacker may entice the target to install a malicious application and remove all existing device locks activated by the target user at a defined time. The new Android version 4.4 (KitKat) has fixed this issue.

More specifically, this vulnerability is caused by a design error on com.android.settings.ChooseLockGeneric class. This class is used to allow the user to modify the type of lock mechanism. The vulnerable code in function updateUnlockMethodAndFinish of this class clears all the existing locks when the supplied password type for the function is identified as type PASSWORD_QUALITY_UNSPECIFIED. A sample of the malicious application can have the following code sequence:

Dell SonicWALL Threat team has researched this vulnerability and released the following signature to protect their customers:

• SPY:4771 Malformed-File apk.OT.1

This vulnerability is identified by CVE as CVE-2013-6271.