What did really change with the new release of the app?

The mobile app market is evolving at a very fast pace. In order to stay in the market and fulfill user's growing demands, developers have to continuously update their apps either to fix issues or to add new features. Users and market managers may have a hard time understanding what really changed in a new release though, and therefore may not make an informative guess of whether updating the app is recommendable, or whether it may pose new security and privacy threats for the user. We propose a ready-to-use framework to analyze the evolution of Android apps. Our framework extracts and visualizes various information ---such as how an app uses sensitive data, which third-party libraries it relies on, which URLs it connects to, etc.--- and combines it to create a comprehensive report on how the app evolved. Besides, we present the results of an empirical study on 235 applications with at least 50 releases using our framework. Our analysis reveals that Android apps tend to have more leaks of sensitive data over time, and that the majority of API calls relative to dangerous permissions are added to the code in releases posterior to the one where the corresponding permission was requested.