Hidden 'Supercookies' Stalk Users, Steal History

Privacy-conscious consumers have yet another thing to worry about in the ongoing battle over online security: supercookies. Unlike regular cookies that track a user's online activities, supercookies are much harder to locate and delete, and are able to reformulate a user profile even after that user deleted his regular cookies, say Stanford and UC Berkeley researchers. And these new kinds of advanced tracking methods dig deep: One "history stealing" tracking service found on a handful of sites peers into your browser history to see if you have visited any one of 1, 500 sites, including ones focused on fertility issues and credit problems.

Big-name sites such as MSN.com and Hulu have been caught using supercookies, though both said it was inadvertent and stopped when the researchers pointed it out, reports the Wall Street Journal. But as consumers grow more savvy about protecting their privacy, advertisers and other companies are growing more savvy and aggressive about tracking, too. Until now, consumer watchdog groups have concentrated on getting more companies to voluntarily adopt self-imposed industry guidelines for protecting privacy, but news of history stealing and supercookies could change that. "You can expect to see more formal public enforcement soon," said an executive with the Council of Better Business Bureaus. (More online security stories.)