Defining and Detecting Environment Discrimination in Android Apps

Environment discrimination—a program behaving differently on different platforms—is used in many contexts. For example, malware can use environment discrimination to thwart detection attempts: as malware detectors employ automated dynamic analysis while running the potentially malicious program in a virtualized environment, the malware author can make the program virtual environment-aware so the malware turns off the nefarious behavior when it is running in a virtualized environment. Therefore, an approach for detecting environment discrimination can help security researchers and practitioners better understand the behavior of, and consequently counter, malware. In this paper we formally define environment discrimination, and propose an approach based on abstract traces and symbolic execution to detect discrimination in Android apps. Furthermore, our approach discovers what API calls expose the environment information to malware, which is a valuable reference for virtualization developers to improve their products. We also apply our approach to the real malware and third-party-researcher designed benchmark apps. The result shows that the algorithm and framework we proposed achieves 97% accuracy.