Abstract
Websites with hyper-partisan, left or right-leaning focus offer content that is typically biased towards the expectations of their target audience. Such content often polarizes users, who are repeatedly primed to specific (extreme) content, usually reflecting hard party lines on political and socio-economic topics. Though this polarization has been extensively studied with respect to content, it is still unknown how it associates with the online tracking experienced by browsing users, especially when they exhibit certain demographic characteristics. For example, it is unclear how such websites enable the ad-ecosystem to track users based on their gender or age. In this work, we take a first step to shed light and measure such potential differences in tracking imposed on users when visiting specific party-line’s websites. For this, we design and deploy a methodology to systematically probe such websites and measure differences in user tracking. This methodology allows us to create user personas with specific attributes like gender and age and automate their browsing behavior in a consistent and repeatable manner. Thus, we systematically study how personas are being tracked by these websites and their third parties, especially if they exhibit particular demographic properties. Overall, we test 9 personas on 556 hyper-partisan websites and find that right-leaning websites tend to track users more intensely than left-leaning, depending on user demographics, using both cookies and cookie synchronization methods and leading to more costly delivered ads.

Short Biography
Panagiotis (Panos) Papadopoulos is a Research Scientist at Telefonica Research. Before that, he was a Security Researcher at Brave Software and a Assistant Researcher at FORTH-ICS, Greece. He holds a MSc and a Ph.D. in Computer Science from the University of Crete, Greece. His interests lie in the area of Network Privacy and Security, Transparency in Digital Advertising, and Fraud Detection. Results of his research have been published in top tier venues such as IEEE INFOCOM, ACM TOIT, USENIX NDSS, ACM WWW, ACM IMC, Springer ESORICS and more.