VioDroid-Finder: automated evaluation of compliance and consistency for Android apps

Rapid growth in the variety and quantity of apps makes it difficult for users to protect their privacy, although existing regulations have been introduced and the Android ecosystem is constantly being improved, there are still violations as privacy policies may not fully comply with regulations, and app behavior may not be fully consistent with privacy policies. To solve such issues, this paper proposes an automated method called VioDroid-Finder aiming at the evaluation of compliance and consistency for Android apps. We first study existing common regulations and conclude the privacy policy content into 7 aspects (i.e., privacy categories), for privacy policies, different compliance rules are required to be complied with in each privacy category. Secondly, we present a policy structure parser model based on the structure extraction/rebuilding method (which can convert the unstructured text to an XML tree) and subtitle similarity calculation algorithm. Thirdly, we propose a violation analyzer using the BERT model to classify each sentence in the privacy policy, we collect existing issues and combine them with manual observations to define 6 types of violations and detect them based on classification results. Then, we propose an inconsistency analyzer that converts permissions, APIs, and GUI into a set of personal information based on static analysis, inconsistencies are detected by comparing that set with personal information declared in the privacy policy. Finally, we evaluate 600 Chinese apps using the proposed method, from which we detect many violations and inconsistencies reflecting the current widespread privacy violation issues.