Decision Support for Mobile App Selection via Automated Privacy Assessment

Mobile apps have entered many areas of our everyday life through smartphones, smart TVs, smart cars, and smart homes. They facilitate daily routines and provide entertainment, while requiring access to sensitive data such as private end user data, e.g., contacts or photo gallery, and various persistent device identifiers, e.g., IMEI. Unfortunately, most mobile users neither pay attention nor fully understand privacy indicating factors that could expose malicious apps. We introduce APPA (Automated aPp Privacy Assessment), a technical tool to assist mobile users making privacy-enhanced app installation decisions. Given a set of empirically validated and publicly available factors which app users typically consider at install-time, APPA creates an output in form of a personalized privacy score. The score indicates the level of privacy safety of the given app integrating three different privacy perspectives. First, an analysis of app permissions determines the degree of privateness preservation after an installation. Second, user reviews are assessed to inform about the privacy-to-functionality trade-off by comparing the sentiment of privacy and functionality related reviews. Third, app privacy policies are analyzed with respect to their legal compliance with the European General Data Protection Regulation (GDPR). While the permissions based score introduces capabilities to filter over-privileged apps, privacy and functionality related reviews are classified with an average accuracy of 79%. As proof of concept, the APPA framework demonstrates the feasibility of user-centric tools to enhance transparency and informed consent as early as during the app selection phase.