Myspace users can use SWF (Flash movies) to make their Layout. But Flash movie can be more than a simple animation. It has the ability to do action. This is called Action Scripting. While you are viewing someone’s Profile with Animated Flash movie your profile data’s like your email address and password can be hijacked from your cookie and saved in a place in behind.
I have recently came through a Digg story published by kinematic where he mentioned the Myspace hack technique. He actually decompiled a SWF file in Myspace to see it’s action script which revealed the secret of the hacking. It is advanced Javascript called AJAX which was used to hack.