Zombie cookie: The tracking cookie that you can’t kill
An online advertising clearinghouse relied on by Google, Yahoo, and Facebook is using controversial cookies that come back from the dead to track the Web surfing of Verizon customers.
The company, called Turn, is taking advantage of a hidden undeletable number that Verizon uses to monitor customers' habits on their smartphones and tablets. Turn uses the Verizon number to respawn tracking cookies that users have deleted.
"We are trying to use the most persistent identifier that we can in order to do what we do," Max Ochoa, Turn's chief privacy officer, told ProPublica. Turn's zombie cookie comes amid a controversy about a new form of tracking the telecom industry has deployed to shadow mobile phone users. Last year, Verizon and AT&T users noticed their carriers were inserting a tracking number into all the Web traffic that transmits from a users' phone—even if the user has tried to opt out.
