Exploiting location-related behaviors without the GPS data on smartphones

摘要

The concerns about location privacy has received considerable attention with the development of Location-based Services (LBSs) over the recent years. Most smartphone users ignore the fact that Apps can infer their locations through accessing WiFi list, although they carefully set location-related permissions to preserve their privacy. Therefore, it is crucial to the public to investigate severe such consequence of WiFi list leakage. In this paper, we develop a tracking scheme for Android, called TrackU, which validate that it is possible to obtain user's location data as well as their location-related behaviors, just by monitoring the WiFi list without any GPS data. Firstly, it periodically scans available Access Points (APs) nearby and queries the geo-location of the device from LBS providers. Secondly, a drift adjusting algorithm proposed obtains the exact locations considering a set of factors, such as historical location information, average signal strength and changing of WiFi list. To preserve the battery life, an optimization is made to dynamically adjust the positioning interval. Based on the obtained data, we design an activity detection algorithm precisely to infer users' daily activities, and identify their travel modes, i.e., hovering, walking, and vehicles. Finally, we implement TrackU and carry out a series of experiments with 39 volunteers from seven cities of China. The experiment results show that our design can detect 91.6% of activities by monitoring the WiFi list, and accurately recognize 94.6% of user's travel mode. (C) 2019 Elsevier Inc. All rights reserved.