You shouldn't collect my secrets: thwarting sensitive keystroke leakage in mobile IME apps

摘要: IME (input method editor) apps are the primary means of interaction on mobile touch screen devices and thus usually granted with access to a wealth private user input. In order understand (in)security apps, this paper first performs systematic study uncovers that many may (intentionally or unintentionally) leak users' sensitive data outside world (mainly due incentives improving user's experience). To thwart threat information leakage while retaining benefits an improved experience, then proposes I-BOX, app-transparent oblivious sandbox minimizes input by confining untrusted predefined security policies. Several key challenges have be addressed proprietary closed-source nature most fact app can arbitrarily store transform before sending it out. By designing system-level transactional execution, I-BOX works seamlessly transparently apps. Specifically, checkpoints app's state keystroke input, monitors analyzes rolls back checkpoint if detects potential danger leaked. A proof concept prototype has been built for Android tested set popular Experimental results show is able incurring very small runtime overhead little impact experience.