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Zombie cookie wars: evil tracking API meant to "raise awareness"

Sep 25, 2010, 19:04 (0 Talkback[s])
(Other stories by Jacqui Cheng)

"The war against persistent zombie cookies—cookies that never seem to lose your data, even when you delete them—rages on, as users learn more about the technology. While awareness is rising thanks to widespread coverage of Flash cookies and, more recently, HTML5's storage capabilities, we have a long way to go before Internet users can avoid persistent tracking. Like all zombie wars, this one will take some time to win; and if you thought things were bad now, they're about to get worse.

"Case in point: evercookie, an open source JavaScript API by developer Samy Kamkar. When implemented by a website, evercookie stores a user ID and cookie data in not two, not three, but eight different places—with more on the way. Among them are your standard HTTP cookies, Flash cookies, RGB values of force-cached PNGs, your Web history, and a smattering of HTML5 storage features. In addition, Silverlight Storage and Java are apparently on the way.

"So, when you delete the cookie in one, three, or five places, evercookie can dip into one of its many other repositories to poll your user ID and restore the data tracking cookies. It works cross-browser, too—if the Local Shared Object cookie is intact, evercookie can spread to whatever other browsers you choose to use on the same machine. Since most users are barely aware of these storage methods, it's unlikely that users will ever delete all of them."

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