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Google Android has become a popular mobile operating system which is increasingly deployed by mobile device manufactures for various platforms. Recent attacks show that Android’s permission framework is vulnerable to applicationlevel privilege escalation attacks, ie, an application may indirectly gain privileges to perform unauthorized actions. The existing proposals for security extensions to Android’s middleware (eg, Kirin, Saint, TaintDroid, or QUIRE) cannot fully and adequately mitigate these attacks or detect Trojans such as Soundcomber that exploit covert channels in the Android system. In this paper we present the design and implementation of XManDroid (eXtended Monitoring on Android), a security framework that extends the monitoring mechanism of Android to detect and prevent application-level privilege escalation attacks at runtime based on a systemcentric system policy. Our implementation dynamically analyzes applications’ transitive permission usage while inducing a minimal performance overhead unnoticeable for the user. Depending on system policy our system representation allows for an effective detection of (covert) channels established through the Android system services and content providers while simultaneously optimizing the rate of false positives. We evaluate the effectiveness of XManDroid on our test suite that simulates known application-level privilege escalation attacks (including Soundcomber), and demonstrate successful detection of attacks that use Android’s inter-component communication (ICC) framework (standard for most attacks). We also performed a usability test to evaluate the impact of …