I just received confirmation from the Google Security Team that the bug I discovered in the iGoogle Facebook Gadget which allowed attackers to log into an other user’s Facebook account bypassing all authentication, has been fixed. So now that the hole has been closed, let’s look at what was happening, shall we?
And that’s exactly what happened on last week, when I spotted this referrer in my blog stats:
http://facebookiggadget.appspot.com/?exp_rpc_js=1&exp_track_js=1&st=c%3Dig%26e%3DAPu7icpJzJJhOouS8TuGegSqFHHI8XHU1r55OllrNbk0ey/aTpkUFx9jPKB/cwgcEZoGfcBuc43x/CuzuEL2cQinYglFvhFWKtlXg6j/JtKC0%252BWsAu3vo/3ZR/WA64J/Fmw1YuUFgT7q&v=fdb2b406636e1f3cff1c5d7e660f59eb&container=ig&view=home&lang=nl&country=BE&up_session=%7B%22uid%22:%221165373488%22, %22session_key%22:%2291d52d2ed5a130fd941b11f1-1175373488%22, %22secret%22:%22fdee68961b3cdee5b51390a4bdeac7a0%22,%22expires%22:0, %22access_token%22:%2283101558C90fd9KfA9KJQh5uT98TqIjxQpzUi4.%22,
You can guess what happened when I opened that URL; the iGoogle Facebook gadget initialized using the embedded credentials, automatically logging me in as the guy that was unlucky enough to have clicked the link to my blog.
But how could this vulnerability have been exploited, you may ask? Well, easy enough; create a page that is viral enough for people to share or like (likespam or even likejacking) and wait for users of the iGoolge Facebook-gadget (there’s over 1 million of them after all) to follow the links, feeding your webserver logfiles with credential-rich referrers.
As Google confirmed this bug indeed has been fixed. The new version of the gadget, which was deployed late last week, does not leak credentials in the referrer-URL any more:
So if anyone asks me what my good deed for this year was; I helped protect 1 million people’s Facebook accounts from being hacked.
Sounds swell, no? ;-)