Evaluation of Third Party Tracking on the Web

In this paper our goal is to measure the presence of trackers and tracking components in websites to identify their dangerousness to privacy. We propose an intuitive privacy scoring model to quantify the use of tracking techniques and identify how users activities are tracked when they are online. We developeded and distributed a firefox add-on that collects the web browsing history of our volunteers along with the detected tracking components and computes the scores of the visited web page. Using our collected dataset, we examine the tracking capabilities in the wild. Our findings show that while cookies- based tracking is present in almost all websites, independently from the content and from the audience, JavaScripts are also present and can also be a major vector of web tracking. We demonstrate that the trackers dangerousness for the user's privacy should not be measured by the number of components but by their presence through the websites and the domains. Correlation was also found between scores and tracking components which confirms that our intuitive scoring model is realistic.