Explore the critical security vulnerabilities associated with HTTP cookie hijacking in this IEEE Symposium presentation. Delve into the widespread privacy implications of partially deployed HTTPS, uncovering how service personalization can inadvertently expose sensitive user information. Examine real-world examples from major websites, including Google, Bing, Yahoo, Amazon, and eBay, revealing the extent of data leakage. Investigate the impact on mobile apps, browser security mechanisms, and ad networks. Learn about the potential for deanonymizing Tor users through these attacks. Analyze the results of a 30-day network measurement study detecting over 282,000 vulnerable accounts. Evaluate current countermeasures, including HSTS and HTTPS Everywhere, and understand their limitations in fully protecting user privacy.