If you are not paying for it, you are the product: How much do advertisers pay to reach you?

TL;DR

This paper introduces a real-time methodology to accurately estimate how much advertisers pay to reach individual users through programmatic advertising, leveraging RTB protocols and encrypted bid analysis.

Contribution

It presents a novel approach for estimating the price paid by advertisers to reach users, including a model for decrypting encrypted bids in real time.

Findings

Achieved over 82% accuracy in estimating user advertising value.

Developed a browser extension and backend system for real-time bid analysis.

Validated methodology with a year-long trace of 1600 mobile users.

Abstract

Online advertising is progressively moving towards a programmatic model in which ads are matched to actual interests of individuals collected as they browse the web. Letting the huge debate around privacy aside, a very important question in this area, for which little is known, is: How much do advertisers pay to reach an individual? In this study, we develop a first of its kind methodology for computing exactly that -- the price paid for a web user by the ad ecosystem -- and we do that in real time. Our approach is based on tapping on the Real Time Bidding (RTB) protocol to collect cleartext and encrypted prices for winning bids paid by advertisers in order to place targeted ads. Our main technical contribution is a method for tallying winning bids even when they are encrypted. We achieve this by training a model using as ground truth prices obtained by running our own "probe" ad-campaigns. We design our methodology through a browser extension and a back-end server that provides it with fresh models for encrypted bids. We validate our methodology using a one year long trace of 1600 mobile users and demonstrate that it can estimate a user's advertising worth with more than 82% accuracy.