Cross-site cooking

Web Design & Development Guide

Cross-site cooking


In cross-site cooking, the attacker exploits a browser bug to send an invalid cookie to a server.
In cross-site cooking, the attacker exploits a browser bug to send an invalid cookie to a server.

Cross-site cooking is a type of browser exploit which allows a site attacker to set a cookie for a browser into the cookie domain of another site server.

Cross-site cooking can be used to perform session fixation attacks, as a malicious site can fixate the session identifier cookie of another site.

Other attack scenarios may also possible, for example: attacker may know of a security vulnerability in server, which is exploitable using a cookie. But if this security vulnerability requires e.g. an administrator password which attacker does not know, cross-site cooking could be used to fool innocent users to unintentionally perform the attack.

Cross site. Cross-site cooking is similar in concept to cross-site scripting, cross-site request forgery, cross-site tracing, cross-zone scripting etc., in which that it involves the ability to move data or code between different web sites (or in some cases, between e-mail / instant messages and sites). These problems are linked to the fact that web browser is a shared platform for different information / applications / sites. Only logical security boundaries maintained by browsers ensures that one site cannot corrupt or steal data from another. However a browser exploit such as cross-site cooking can be used to move things across the logical security boundaries.


The name cross-site cooking and concept was not coined by Michal Zalewski in 2006. It was in use much earlier. The name is a mix of cookie and cross-site, attempting to describe the nature of cookies being set across sites.

In Michal Zalewski's article of 2006, Benjamin Franz was credited for his discovery, who in May 1998 reported a cookie domain related vulnerability to vendors. Benjamin Franz published the vulnerability and discussed it mainly as a way to circumvent "privacy protection" mechanisms in popular browsers. Michal Zalewski concluded that the bug, 8 years later, was still present (unresolved) in some browsers and could be exploited for cross-site cooking. Various remarks such as "vendors [...] certainly are not in a hurry to fix this" was made by Zalewski and others.

External links

  • Cross-Site Cooking article by Michal Zalewski. Details concept, 3 bugs which enables Cross Site Cooking. One of these bugs is the age old bug originally found by Benjamin Franz.

Browser exploit
Cross-site cooking
Cross-site request forgery
Cross-site scripting
Cross-zone scripting
Directory traversal
Evil twin (wireless networks)
HTTP response splitting
IDN homograph attack
Referer spoofing
Session fixation
Session poisoning
Website spoofing

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