Simon Willison’s Weblog

5th November 2009

Facebook and MySpace security: backdoor wide open, millions of accounts exploitable (via) Amazingly, both services had wide open holes in their crossdomain.xml files. Facebook were serving allow-access-from-domain=“*” in the crossdomain.xml file on one of their subdomains (a subdomain that still had access to the user’s profile information) while MySpace were opting in farm.sproutbuilder.com, a service which allowed anyone to upload arbitrary SWF files.