Since its introduction, Android’s in-app billing service has quickly gained popularity. The in-app billing service allows users to pay for options, services, subscriptions, and virtual goods from within mobile apps themselves. In-app billing is attractive for developers because it is easy to integrate, and has the advantage that the developer does not need to be concerned with managing financial transactions.
In this paper, we present the first fully-automated attack against the in-app billing service on Android. Using our prototype, we conducted a robustness study against our attack, analyzing 85 of the most popular Android apps that make use of in-app billing. We found that 60% of these apps were easily and automatically crackable. We were able to bypass highly popular and prominent games such as Angry Birds and Temple Run, each of which have millions of users. Based on our study, we developed a defensive technique that specifically counters automated attacks against in-app billing. Our technique is lightweight and can be easily added to existing applications.