MR-Droid: A Scalable and Prioritized Analysis of Inter-App Communication Risks

Inter-Component Communication (ICC) enables useful interactions between mobile apps. However, misuse of ICC exposes users to serious threats, allowing malicious apps to access privileged user data via another app. Unfortunately, existing ICC analyses are largely insufficient in both accuracy and scalability. Most approaches rely on single-app ICC analysis which results in inaccurate and excessive alerts. A few recent works use pairwise app analysis, but are limited by small data sizes and scalability. In this paper, we present MR-Droid, a MapReduce-based computing framework for accurate and scalable inter-app ICC analysis in Android. MR-Droid extracts data-flow features between multiple communicating apps to build a large-scale ICC graph. We leverage the ICC graph to provide contexts for inter-app communications to produce precise alerts and prioritize risk assessments. This scheme requires quickly processing a large number of app-pairs, which is enabled by our MapReduce-based program analysis. Extensive experiments on 11,996 apps from 24 app categories (13 million pairs) demonstrate the effectiveness of our risk prioritization scheme. Our analyses also reveal new real-world hijacking attacks and collusive app pairs. Based on our findings, we provide practical recommendations for reducing inter-app communication risks.