Online advertising company Turn said Friday it will stop using a controversial tracking method by early next month that aids serving targeted advertisements to Verizon’s mobile customers.
Turn was criticized for using a persistent numerical identifier that Verizon attaches to the Internet traffic of its mobile customers to recreate a history of a person’s web browsing traffic even if a person has deleted the record.
Verizon uses the number, called a UIDH (Unique Identifier Header), for two advertising programs. But the company has been criticized for labeling Internet traffic because third-parties such as Turn can use it for their own purposes.
Turn’s practices were revealed last week in a blog post by computer scientist Jonathan Mayer of Stanford University and by news outlet ProPublica.
Turn uses the UIDH to recreate its own cookie, which is a small data file that records information such as web browsing, even if a person has deleted that file.
The practice—which has been referred to as a “zombie” cookie—isn’t illegal. But privacy advocates contend users may be unaware that they are still being tracked.
After ProPublica’s story, Turn defended its practices, arguing that deleting a cookie isn’t a recognized method for opting out of targeted advertising. Instead, it suggested using opt-out methods endorsed by the Network Advertising Initiative and the Digital Advertising Alliance.
However on Friday, Turn’s General Counsel and Chief Privacy Officer Max Ochoa wrote that due to the concerns, Turn will not use Verizon’s UIDH starting in early February.
Ochoa still maintained that Turn’s practices complied with self-regulatory guidelines within the online advertising industry. He also claimed there were inaccuracies in Mayer’s and ProPublica’s pieces.
The Electronic Frontier Foundation, which criticized both companies last week, called on Turn to stop using Verizon’s identifier immediately rather than three weeks from now.
Verizon should also stop tagging mobile web traffic since it “enables any company to use the identifier in similarly abusive ways, some of which may not be visible to users,” wrote Jacob Hoffman-Andrews, the EFF’s senior staff technologist.
AT&T stopped assigning UIDHs to mobile traffic in November after running tests, according to ProPublica.
It is possible to stop Verizon from tagging mobile traffic. Encrypting all web traffic that comes from a mobile device, such as by using a VPN service or the Tor anonymity network, will prevent Verizon from tampering with it at the carrier level.
Alternatively, users can stop online advertising companies from monitoring browsing activities with special software.
Tools including AdAway, AdBlock, AdBlock Plus and Disconnect Pro will block online trackers that send information back to advertising companies, according to the EFF. The organization published a table of the applications last Thursday.