Hacker breaks into Mark Zuckerberg's Facebook page to expose site's vulnerability.

Khalil Shreateh, tried to warn Facebook about a security threat that allows anyone to post on strangers' walls but no one listened until he took his warning to the very top. He posted on Mark Zuckerberg's wall by exploiting the very glitch he'd discovered and got a speedy response. But Facebook says he violated their terms of service and will not receive the $500 bounty usually awarded to those who find security holes.