DefDroid: Securing Android with Fine-Grained Security Policy

Android occupies the absolute dominant position in mobile operating system and has the largest market share. Meanwhile, Android faces the risk of malicious insiders leaking sensitive information. In this paper, we present DefDroid, a repackaging tool for enforcing security policies by modifying Android applications without root privilege. The main advantages of DefDroid are that it provides a user-friendly interface to configure fine-grained policies and it supplies multiple deployment methods. We have implemented policies aimed at three types of services of Android system, i.e., content provider, file system, and network. We choose 74 arbitrary applications from Android market and the experimental results show that the successful rate of repackaging applications is about 94.6% which effectively improve the privacy security of Android system while the increased overhead can be tolerated. Keywords—Android; permission restriction; repackage; bytecode