500 million guests affected by data breach at Marriott's Starwood unit

The Marriott hack may rank only below Yahoo as one of the biggest of personal data, when 3 billion users were exposed to a 2013 security breach

Marriott International said it’s investigating a hack of the guest reservation database at its Starwood unit that may be one of the biggest such breaches in corporate history. Marriott shares slumped 5.6 per cent in pre-market trading.

The attack is troubling not just because of its sheer size, but also the level of detail potentially stolen by the attackers. The hack affects some 500 million guests, and for about 327 million of them, the data included passport numbers, emails and mailing addresses, Marriott said. Some credit card details may also have been taken.

The Marriott hack may rank only below Yahoo as