May 28, 2011, 10:03 AM — A security researcher has discovered a means of hijacking sensitive information from cookies in Internet Explorer. The 'cookiejacking' technique could expose credentials from Facebook, Twitter, Gmaiil, or other online services, but Microsoft doesn't consider it a serious threat. So, is the sky falling, is the security researcher crying wolf, or is the real risk somewhere in between.
Security researcher Rosario Valotta recently demonstrated the 'cookiejacking' technique, and has details of the attack on his blog. The 'cookiejacking' threat, and underlying zero-day flaw affect all versions of Internet Explorer running on any version of Windows, so the pool of potential victims is significant.
What Is a Cookie?A cookie is a small text file used by a Web browser or application to store information like site preferences, or user account credentials for site authentication.
What Is 'Cookiejacking'?The technique exploits a flaw that bypasses the Security Zone protection in Internet Explorer to enable the attacker to capture the contents of cookies that should not be exposed.
What Is at Risk?Most text files contain text that would of little value. But, if you are logged in to a site like Facebook, Twitter, or Gmail, cookies are used to store user account information needed to authenticate so you don't have to log in repeatedly. If an attacker can hijack these cookies, they could impersonate you or access sensitive data within the affected site or service.
Is It a Serious Threat?The attack is not trivial to pull off. The actual 'cookiejacking' is just one piece of a larger puzzle that requires different attack techniques, and duping the user into becoming a willing participant.
Microsoft's Jerry Bryant downplayed the threat based on the complexity of the attack and the level of user interaction required for it to work. "In order to possibly be impacted a user must visit a malicious website, be convinced to click and drag items around the page and the attacker would need to target a cookie from the website that the user was already logged into."