Verizon Wireless and AT&T have both admitted to using a tool called supercookies to track the web usage of their customers.
The supercookies log which web sites Verizon and AT&T customers visit, generating data that Verizon and AT&T can sell to advertisers.
The supercookies allow Verizon and AT&T to monitor customers who’ve opted out of traditional cookie-based tracking. The supercookies can’t be erased, nor evaded by using private browsing modes as they aren’t stored on phones.
Instead, they’re stored on Verizon’s network. Verizon says it notified customers about the supercookies, though the effectiveness of the outreach has been called to question. Verizon also says it has taken steps to protect customer privacy.
For example, the supercookie codes are a random string of numbers and letters that are changed regularly. Verizon says the data generated by its supercookies are only available to participants of its Precision Markets Insights advertising program.
AT&T’s supercookie codes are changed every day, but its program is still in the trial stage and not yet fully deployed. The companies contend the codes are anonymous, but security researchers cited by The Washington Post say the data can be de-anonymized to reveal identity info.
The Electronic Frontier Foundation has reached out to the FCC about the legality of the tracking tools. It is weighing whether or not to take legal action to prevent the carriers from using them.
