Presented at
DEF CON 33 (2025),
Aug. 8, 2025, 4:30 p.m.
(45 minutes).
Google's Privacy Sandbox initiative aims to provide privacy-preserving alternatives to third-party cookies by introducing new web APIs. This talk will examine potential client-side deanonymization attacks that can compromise user privacy by exploiting vulnerabilities and misconfigurations within these APIs.
I will explore the Attribution Reporting API, detailing how debugging reports can bypass privacy mechanisms like Referrer-Policy, potentially exposing sensitive user information. I will also explain how destination hijacking, in conjunction with a side-channel attack using storage limit oracles, can be used to reconstruct browsing history, demonstrating a more complex deanonymization technique.
Additionally, I will cover vulnerabilities in the Shared Storage API, illustrating how insecure cross-site worklet code can leak data stored within Shared Storage, despite the API being deliberately designed to prevent direct data access. Real-world examples and potential attack scenarios will be discussed to highlight the practical implications of these vulnerabilities.
References:
- [link](https://github.com/WICG/attribution-reporting-api)
Presenters:
-
Eugene "spaceraccoon" Lim
Eugene Lim is a security researcher and white hat hacker. From Amazon to Zoom, he has helped secure applications from a range of vulnerabilities. His work has been featured at top conferences such as Black Hat, DEF CON, and industry publications like WIRED and The Register.
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