Towards Understanding First-Party Cookie Tracking in the Field

Abstract

Third-party web tracking is a common, and broadly used technique on the Web. Almost every step of users' is tracked, analyzed, and later used in different use cases (e.g., online advertisement). Different defense mechanisms have emerged to counter these practices (e.g., the recent step of browser vendors to ban all third-party cookies). However, all of these countermeasures only target third-party trackers, and ignore the first party because the narrative is that such monitoring is mostly used to improve the utilized service (e.g., analytical services).In this paper, we present a large-scale measurement study that analyzes tracking performed by the first party but utilized by a third party to circumvent standard tracking preventing techniques (i.e., the first party performs the tracking in the name of the third party). We visit the top 15,000 websites to analyze first-party cookies used to track users and a technique called "DNS CNAME cloaking", which can be used by a third party to place firstparty cookies. Using this data, we show that 76% sites in our dataset effectively utilize such tracking techniques, and in a long-running analysis we show that the usage of such cookies increased by more than 50% over 2021. Furthermore, we shed light on the ecosystem utilizing first-party trackers, and find that the established trackers already use such tracking, presumably to avoid tracking blocking.

Thou Shalt Not Reject: Analyzing Accept-Or-Pay Cookie Banners on the Web

“…If the cookie domain matches one of the domains in the justdomains list, we classify it as a tracking cookie. Note that there exist other techniques to track users that we do not consider in this research, e.g., browser fingerprinting [1], tracking using first-party cookies [8,19,45], and the use of invisible pixels and click IDs [4], as we specifically focus on studying the emergence of cookiewalls. Thus, in the future, a more nuanced analysis focusing on other tracking techniques can be conducted.…”