TKPERM: Cross-platform Permission Knowledge Transfer to Detect Overprivileged Third-party Applications

Permission-based access control enables users to manage and control their sensitive data for third-party applications. In an ideal scenario, third-party application includes enough details to illustrate the usage of such data, while the reality is that many descriptions of third-party applications are vague about their security or privacy activities. As a result, users are left with insufficient details when granting sensitive data to these applications. Prior works, such as WHYPER and AutoCog, have addressed the aforementioned problem via a so-called permission correlation system. Such a system correlates thirdparty applications’ description with their requested permissions and determines an application as overprivileged, if a mismatch between the requested permission and the description is found. However, although prior works are successful on their own platforms, such as Android eco-system, they are not directly applicable to new platforms, such as Chrome extensions and IFTTT, without extensive data labeling and parameter tuning. In this paper, we design, implement, and evaluate a novel system, called TKPERM, which transfers knowledges of permission correlation systems across platforms. Our key idea is that these varied platforms with different use cases—like smartphones, IoTs, and desktop browsers—are all user-facing and thus allow the knowledges to be transferrable across platforms. Particularly, we adopt a greedy selection algorithm that picks the best source domains to transfer to the target permission on a new platform. TKPERM achieves 90.02% overall F1 score after transfer, which is 12.62% higher than the one of a model trained directly on the target domain without transfer. Particularly, TKPERM has 91.83% F1 score on IFTTT, 89.13% F1 score on Chrome-Extension, and 89.1% F1 score on SmartThings. TKPERM also successfully identified many real-world overprivileged applications, such as a gaming hub requesting location permissions without legitimate use.