A Privacy Analysis of Cross-device Tracking


Sebastian Zimmeck, Carnegie Mellon University; Jie S. Li and Hyungtae Kim, unaffiliated; Steven M. Bellovin and Tony Jebara, Columbia University


Online tracking is evolving from browser- and device-tracking to people-tracking. As users are increasingly accessing the Internet from multiple devices this new paradigm of tracking—in most cases for purposes of advertising—is aimed at crossing the boundary between a user’s individual devices and browsers. It establishes a person-centric view of a user across devices and seeks to combine the input from various data sources into an individual and comprehensive user profile. By its very nature such cross-device tracking can principally reveal a complete picture of a person and, thus, become more privacy-invasive than the siloed tracking via HTTP cookies or other traditional and more limited tracking mechanisms. In this study we are exploring cross-device tracking techniques as well as their privacy implications.

Particularly, we demonstrate a method to detect the occurrence of cross-device tracking, and, based on a cross-device tracking dataset that we collected from 126 Internet users, we explore the prevalence of cross-device trackers on mobile and desktop devices. We show that the similarity of IP addresses and Internet history for a user’s devices gives rise to a matching rate of F-1 = 0.91 for connecting a mobile to a desktop device in our dataset. This finding is especially noteworthy in light of the increase in learning power that cross-device companies may achieve by leveraging user data from more than one device. Given these privacy implications of cross-device tracking we also examine compliance with applicable self-regulation for 40 cross-device companies and find that some are not transparent about their practices.

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@inproceedings {203894,
author = {Sebastian Zimmeck and Jie S. Li and Hyungtae Kim and Steven M. Bellovin and Tony Jebara},
title = {A Privacy Analysis of Cross-device Tracking},
booktitle = {26th USENIX Security Symposium (USENIX Security 17)},
year = {2017},
isbn = {978-1-931971-40-9},
address = {Vancouver, BC},
pages = {1391--1408},
url = {https://www.usenix.org/conference/usenixsecurity17/technical-sessions/presentation/zimmeck},
publisher = {USENIX Association},
month = aug

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