'Rosetta Flash' Attack Leverages JSONP Callbacks To Steal Credentials

New submitter newfurniturey writes: A new Flash and JSONP attack combination has been revealed to the public today. It has been dubbed the "Rosetta Flash" attack. JSONP callback functions normally return a JSON blob wrapped in a user-specified callback function, which the browser will then execute as JavaScript. Nothing out of the ordinary here. However, the new attack has leveraged a method of crafting a Flash file to contain a restricted character set that's usable within JSONP callbacks (i.e. in a URL). By combining the two, the attack demonstrates it's possible to use a JSONP URL with the contents of the crafted Flash file as the callback function. When set as the data of a standard HTML object tag, the SWF file executes on the targeted site, bypassing all Same-Origin policies in place. Services such as Google, YouTube, Twitter, Tumblr and eBay were found vulnerable to this attack. Several of these services fixed the vulnerability with a patch prior to the public release, and Tumblr patched within hours of the release.