Understanding the Performance Costs and Benefits of Privacy-focused Browser Extensions Kevin Borgolte Nick Feamster
[email protected] [email protected] Princeton University University of Chicago ABSTRACT 1 INTRODUCTION Advertisements and behavioral tracking have become an invasive The online advertisement (ad) industry has been one of the fastest nuisance on the Internet in recent years. Indeed, privacy advocates growing industries in the recent years, growing from over 108 and expert users consider the invasion signifcant enough to war- billion US dollars in 2018 to an estimated 129 billion US dollars rant the use of ad blockers and anti-tracking browser extensions. in 2019 in the United States [34], and to estimated 333 billion US At the same time, one of the largest advertisement companies in dollars in 2019 globally [12]. This growth has sparked numerous the world, Google, is developing the most popular browser, Google academic studies of various angles of online ads, from understand- Chrome. This confict of interest, that is developing a browser (a ing the underlying economics, the overall scale of it, mechanisms user agent) and being fnancially motivated to track users’ online and techniques used, as well as how miscreants are abusing it to behavior, possibly violating their privacy expectations, while claim- proft. ing to be a "user agent," did not remain unnoticed. As a matter of Academic and industry studies on the techniques that online fact, Google recently sparked an outrage when proposing changes ads are relying on have led to privacy advocates and expert users to Chrome how extensions can inspect and modify requests to "im- arguing that the ad companies’ tracking and data collection, which prove extension performance and privacy," which would render provides the foundation for the most prevalent online ads today, existing privacy-focused extensions inoperable.