Marriott estimates that 339 million guest records worldwide were affected following a cyber-attack in 2014 on Starwood Hotels and Resorts Worldwide Inc. The attack, from an unknown source, remained undetected until September 2018, by which time the company had been acquired by Marriott. The personal data involved differed between individuals but may have included names, email addresses, phone numbers, unencrypted passport numbers, arrival/departure information, guests’ VIP status and loyalty programme membership number.

The precise number of people affected is unclear as there may have been multiple records for an individual guest. Seven million guest records related to people in the UK. The ICO’s investigation found that there were failures by Marriott to put appropriate technical or organisational measures in place to protect the personal data being processed on its systems, as required by the General Data Protection Regulation (GDPR).

Source: ICO