After reading Homakov's and Nir's discussions I started looking for some bugs myself. And guess what? ~10 hours later I found another access_token-stealing exploit that has the same implications as Nir's exploit (although mine doesn't work in all browsers). Reported it 2 days ago.
Wouldn't surprise me if there's more bugs/exploits to be discovered :(
And since Homakov gave quite a detailed description of the class of bugs, it would be quite dangerous to use a browser with an active session to facebook now.
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Facebook's OAuth2 implementation is so broken. Homakov found a X-XSS-Protection-related issue: http://homakov.blogspot.no/2013/02/hacking-facebook-with-oau....
After reading Homakov's and Nir's discussions I started looking for some bugs myself. And guess what? ~10 hours later I found another access_token-stealing exploit that has the same implications as Nir's exploit (although mine doesn't work in all browsers). Reported it 2 days ago.
Wouldn't surprise me if there's more bugs/exploits to be discovered :(
And since Homakov gave quite a detailed description of the class of bugs, it would be quite dangerous to use a browser with an active session to facebook now.
No proof of the exploit?
Facebook acknowledged it and the researcher who found the vulnerability got a bounty from FB.
You might be interested in Nir's discussion of the bug: http://www.nirgoldshlager.com/2013/02/how-i-hacked-facebook-...