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The most popular static taint analysis tools for Android allow users to change the underlying analysis algorithms through configuration options. However, the large configuration spaces make it difficult for developers and users alike to understand the full capabilities of these tools, and studies to-date have only focused on individual configurations. In this work, we present the first study that evaluates the configurations in Android taint analysis tools, focusing on the two most popular tools, FlowDroid and DroidSafe. First, we perform a manual code investigation to better understand how configurations are implemented in both tools. We formalize the expected effects of configuration option settings in terms of precision and soundness partial orders which we use to systematically test the configuration space. Second, we create a new dataset of 756 manually classified flows across 18 open-source real-world apps and conduct large-scale experiments on this dataset and micro-benchmarks. We observe that configurations make significant tradeoffs on the performance, precision, and soundness of both tools. The studies to-date would reach different conclusions on the tools' capabilities were they to consider configurations or use real-world datasets. In addition, we study the individual options through a statistical analysis and make actionable recommendations for users to tune the tools to their own ends. Finally, we use the partial orders to test the tool configuration spaces and detect 21 instances where options behaved in unexpected and incorrect ways, demonstrating the need for rigorous testing of configuration spaces. |
