• Researchers Expose Cunning Online Tracking Service That Can’t Be Dodged | Epicenter | Wired.com
    http://www.wired.com/epicenter/2011/07/undeletable-cookie

    Researchers at U.C. Berkeley have discovered that some of the net’s most popular sites are using a tracking service that can’t be evaded — even when users block cookies, turn off storage in Flash, or use browsers’ “incognito” functions.

    The service, called KISSmetrics, is used by sites to track the number of visitors, what the visitors do on the site, and where they come to the site from — and the company says it does a more comprehensive job than its competitors such as Google Analytics.

    ...

    So if a user came to Hulu.com from an ad on Facebook, and then later, using a different browser on the same computer, visited Hulu.com from Google, and then at some point signed up for the premium service, KISSmetrics would be able to tell Hulu all about that user’s path to purchase (without knowing who that person was). That tracking trail would remain in place even if a user deleted her cookies, due to code that stores the unique ID in places other than in a traditional cookie.

    The research was published Friday by a team UC Berkeley privacy researchers that includes veteran privacy lawyer Chris Hoofnagle and noted privacy researcher Ashkan Soltani.

    “The stuff works even if you have all cookies blocked and private-browsing mode enabled,” Soltani said. “The code itself is pretty damning.”