Sadly, it turns out that many Web sites do not properly set the “Encrypted Sessions Only” property of their cookies.
Because HTTPS cookies are full of tasty authentication information, they can be used to access online banking accounts, Webmail accounts, and the like.
Perry proposes the following test to see whether sites you use are vulnerable: “To check your sites under Firefox, go to the Privacy tab in the Preferences window, and click on ‘Show Cookies.’ For a given site, inspect the individual cookies for the top level name of the site, and any subdomain names, and if any have ‘Send For: Encrypted connections only,’ delete them.
Having tried these steps with two “Encrypted connections only” Google (NSDQ: GOOG) cookies, Google appears to be vulnerable to a CookieMonster attack. A Google spokesperson confirmed this to be the case and said the company’s engineers are working with Perry to eliminate the vulnerability.
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