A Large-Scale Study of Cookie Banner Interaction Tools and their Impact on Users’ Privacy

Cookie notices (or cookie banners) are a popular mechanism for websites to provide (European) Internet users a tool to choose which cookies the site may set.
Banner implementations range from merely providing information that a site uses cookies over offering the choice to accepting or denying all cookies to allowing fine-grained control of cookie usage.
Users frequently get annoyed by the banner's pervasiveness as they interrupt ``natural'' browsing on the Web.
As a remedy, different browser extensions have been developed to automate the interaction with cookie banners.

In this work, we perform a large-scale measurement study comparing the effectiveness of extensions for ``cookie banner interaction.''
We configured the extensions to express different privacy choices (e.g., accepting all cookies, accepting functional cookies, or rejecting all cookies) to understand their capabilities to execute a user's preferences.
The results show statistically significant differences in which cookies are set, how many of them are set, and which types are set---even for extensions that aim to implement the same cookie choice.
Extensions for ``cookie banner interaction'' can effectively reduce the number of set cookies compared to no interaction with the banners.
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However, all extensions increase the tracking requests significantly except when rejecting all cookies.