Data breach hunter Chris Vickery has digitally unearthed terabytes of private, personal and financial data online. Marriott International has said there was some unauthorized access to the data. Vickery: Usually when there is a breach like this, the data is encrypted, ransomed or (the victim is) extorted. The breach is typically an automated process via a script. With those companies it was an automated exploit that finds the weakness, goes in and encrypts and then ransoms the data. There are a lot of possibilities in terms of what happened.
Source: https://threatpost.com/chris-vickery-on-the-marriott-breach-and-a-rash-of-recent-high-profile-hacks/139574/