since 2007, the Android operating system (OS) has enjoyed an incredible rate of popularity. As of 2013, the Android OS holds 79.3 percent of global smartphone market shares. Meanwhile, a number of Android security and privacy vulnerabilities have been exposed in the past several years. Although the Android permission system gives users an opportunity to check the permission request of an application (app) before installation, few users have knowledge of what all these permission requests stand for; as a result, they fails to warn users of security risks. Meanwhile, an increasing number of apps specified to enhance security and protect user privacy have appeared in Android app markets.