How Verizon and Turn Defeat Browser Privacy Protections
Verizon advertising partner Turn has been caught using Verizon Wireless’s UIDH tracking header to resurrect deleted tracking cookies and share them with dozens of major websites and ad networks, forming a vast web of non-consensual online tracking. Explosive research from Stanford security expert Jonathan Mayer shows that, as we warned in November, Verizon’s UIDH header is being used as an undeletable perma-cookie that makes it impossible for customers to meaningfully control their online privacy.
Mayer’s research, described in ProPublica, shows that advertising network and Verizon partner Turn is using the UIDH header value to re-identify and re-cookie users who have taken careful steps to clear their cookies for privacy purposes. This contradicts standard browser privacy controls, users’ expectations, and Verizon’s own claims that the UIDH header won’t be used to track users because it changes periodically.
This spectacular violation of Verizon users’ privacy—made all the worse because of Verizon’s failure to allow even an opt-out—has already had far-reaching consequences.
UPDATE (1/17/15): Ad Network Turn Will Suspend Zombie Cookie Program. When Will Verizon?