Facebook top dog Mark Zuckerberg had several of his social media accounts breached and defaced, according to reports that surfaced Sunday. Zuckerberg's Twitter, LinkedIn and Pinterest memberships were hacked, but evidence of the attacks quickly disappeared. In addition to requiring passwords, Twitter and LinkedIn protect their accounts with optional two-factor authentication. "My guess is that Zuckerberg did not have [2FA] turned on on these sites," said Centrify security strategist Chris Webber.