To detect the potential malicious mobile applications that may cause data leakages, this paper¹ proposes to take advantage of the attack-neutral and hard-to-avoid system calls of the mobile system, reconstructing an activity graph for each application to reflect its interactions with the system. This paper makes efforts to automate the activity graph generation in Android, with the main contribution being an open source tool that can be of great assistance for the test team of application stores. The tool's effectiveness has been validated by our evaluation against some existing or home-brewed mobile applications that leak data.