The openness of Android allows users to download Apps from a variety of sources besides from Google Play. However, this mechanism also brings risks to developers, as attackers can tamper with others’ Apps, modify functionality, or bypass payment mechanisms, and then repackage them as cracked versions and release them on third-party App stores, resulting in loss of developer revenue. This session will introduce common tampering techniques for Android Apps and propose countermeasures to help developers reduce the risk of Apps tampering.