Zombie cookie

A zombie cookie is a piece of data usually used for tracking users, which is created by a web server while a user is browsing a website, and placed on the user's computer or other device by the user's web browser, similar to regular HTTP cookies, but with mechanisms in place to prevent the deletion of the data by the user. Zombie cookies could be stored in multiple locations—since failure to remove all copies of the zombie cookie will make the removal reversible, zombie cookies can be difficult to remove.^[1] Since they do not entirely rely on normal cookie protocols, the visitor's web browser may continue to recreate deleted cookies even though the user has opted not to receive cookies.

The term was used by Attorney Joseph H. Malley, who initiated the super-cookie class actions in 2010.

^ Sorensen, Ove (2013). "Zombie-cookies: Case studies and mitigation". 8th International Conference for Internet Technology and Secured Transactions (ICITST-2013). London: IEEE. pp. 321–326. doi:10.1109/ICITST.2013.6750214. ISBN 978-1-908320-20-9.

[1] Sorensen, Ove (2013). "Zombie-cookies: Case studies and mitigation". 8th International Conference for Internet Technology and Secured Transactions (ICITST-2013). London: IEEE. pp. 321–326. doi:10.1109/ICITST.2013.6750214. ISBN 978-1-908320-20-9.

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