Tracing Information Flows Between Ad Exchanges Using Retargeted Ads Muhammad Ahmad Bashir, Sajjad Arshad, William Robertson, Christo Wilson Northeastern University Your Privacy Footprint 2 Your Privacy Footprint 2 Your Privacy Footprint 2 Your Privacy Footprint 2 Your Privacy Footprint 2 Your Privacy Footprint 2 Real Time Bidding 3 Real Time Bidding • RTB brings more flexibility in the ad ecosystem. • Ad request managed by an Ad Exchange which holds an auction. • Advertisers bid on each ad impression. 3 Real Time Bidding • RTB brings more flexibility in the ad ecosystem. • Ad request managed by an Ad Exchange which holds an auction. • Advertisers bid on each ad impression. Cookie matching is a prerequisite. Exchange Advertiser 3