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There has been a proliferation of mobile apps in the Medical, as well as Health&Fitness categories. These apps have a wide audience, from medical providers, to patients, to end users who want to track their fitness goals. The low barrier to entry on mobile app stores raises questions about the diligence and competence of the developers who publish these apps, especially regarding the practices they use for user data collection, processing, and storage. To help understand the nature of data that is collected, and how it is processed, as well as where it is sent, we developed a tool named PIT (Personal Information Tracker) and made it available as open source. We used PIT to perform a multi-faceted study on 2832 Android apps: 2211 Medical apps and 621 Health&Fitness apps. We first define Personal Information (PI) as 17 different groups of sensitive information, e.g., user’s identity, address and financial information, medical history or anthropometric data. PIT first extracts the elements in the app’s User Interface (UI) where this information is collected. The collected information could be processed by the app’s own code or third-party code; our approach disambiguates between the two. Next, PIT tracks, via static analysis, where the information is “leaked”, i.e., it escapes the scope of the app, either locally on the phone or remotely via the network. Then, we conduct a link analysis that examines the URLs an app connects with, to understand the origin and destination of data that apps collect and process. We found that most apps leak 1–5 PI items (email, credit card, phone number, address, name, being the most frequent). Leak destinations include the network (25%), local databases (37%), logs (23%), and files or I/O (15%). While Medical apps have more leaks overall, as they collect data on medical history, surprisingly, Health&Fitness apps also collect, and leak, medical data. We also found that leaks that are due to third-party code (e.g., code for ads, analytics, or user engagement) are much more numerous (2x–12x) than leaks due to app’s own code. Finally, our link analysis shows that most apps access 20–80 URLs (typically third-party URLs and Cloud APIs) though some apps could access more than 1,000 URLs.
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DAISY: Dynamic-Analysis-Induced Source Discovery for Sensitive Data
Mobile apps are widely used and often process users’ sensitive data. Many taint analysis tools have been applied to analyze sensitive information flows and report data leaks in apps. These tools require a list of sources (where sensitive data is accessed) as input, and researchers have constructed such lists within the Android platform by identifying Android API methods that allow access to sensitive data. However, app developers may also define methods or use third-party library’s methods for accessing data. It is difficult to collect such source methods because they are unique to the apps, and there are a large number of third-party libraries available on the market that evolve over time. To address this problem, we propose DAISY, a Dynamic-Analysis-Induced Source discoverY approach for identifying methods that return sensitive information from apps and third-party libraries. Trained on an automatically labeled data set of methods and their calling context, DAISY identifies sensitive methods in unseen apps. We evaluated DAISY on real-world apps and the results show that DAISY can achieve an overall precision of 77.9% when reporting the most confident results. Most of the identified sources and leaks cannot be detected by existing technologies.
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- PAR ID:
- 10397875
- Date Published:
- Journal Name:
- ACM Transactions on Software Engineering and Methodology
- ISSN:
- 1049-331X
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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- Free Publicly Accessible Full Text
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Accepted Manuscript1.0
- Journal Article:
- https://doi.org/10.1145/3569936
