TaintDroid: An Information-Flow Tracking System for Realtime Privacy Monitoring on Smartphones Today's smartphone operating systems fail to provide users with adequate control and visibility into how third-party applications use their private data. We present TaintDroid, an efficient, system-wide dynamic taint tracking and analysis system for the popular Android platform that can simultaneously track multiple sources of sensitive data. TaintDroid's efficiency to perform real-time analysis stems from its novel system design that leverages the mobile platform's virtualized system architecture. TaintDroid incurs only 14% performance overhead on a CPU-bound micro-benchmark with little, if any, perceivable overhead when running third-party applications. We use TaintDroid to study the behavior of 30 popular third-party Android applications and find several instances of misuse of users' private information. We believe that TaintDroid is the first working prototype demonstrating that dynamic taint tracking and analysis provides informed use of third-party applications in existing smartphone operating systems.