Demir, NurullahTheis, DanielUrban, TobiasPohlmann, NorbertChristian Wressnegger, Delphine Reinhardt2023-01-242023-01-242022978-3-88579-717-3https://dl.gi.de/handle/20.500.12116/40130Third-party tracking is a common and broadly used technique on the Web. Different defense mechanisms have emerged to counter these practices (e. g. browser vendors that ban all third-party cookies). However, 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. 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 first-party cookies. Using this data, we show that 76% of sites effectively utilize such tracking techniques. In a long-running analysis, we show that the usage of such cookies increased by more than 50% over 2021.enfirst-party trackingcookiesprivacyCNAME cloakingtracking method10.18420/sicherheit2022_011617-5468