Marriott discloses data breach that affected up to 500M guests

NEW YORK — Hackers stole information on as many as 500 million guests of the Marriott hotel empire over four years, obtaining credit card and passport numbers and other personal data, the company said Friday as it acknowledged one of the largest security breaches in history.

The full scope of the failure was not immediately clear. Marriott was trying to determine if the records included duplicates, such as a single person staying multiple times.

The affected hotel brands were operated by Starwood before it was acquired by Marriott in 2016. They include W Hotels, St. Regis, Sheraton, Westin, Element, Aloft, The Luxury Collection, Le Méridien and Four Points. Starwood-branded timeshare properties were also affected. None of the Marriott-branded chains were threatened.

The crisis quickly emerged as one of the biggest data breaches on record.

“On a scale of 1 to 10 and up, this is one of those No. 10 size breaches. There have only been a few of them of this scale and scope in the last decade,” said Chris Wysopal, chief technology officer of Veracode, a security company.

By comparison, last year’s Equifax hack affected more than 145 million people. A Target breach in 2013 affected more than 41 million payment card accounts and exposed contact information for more than 60 million customers.

Security analysts were especially alarmed to learn that the breach began in 2014. While such failures often span months, four years is extreme, said Yonatan Striem-Amit, chief technology officer of Cybereason.

It was unclear what hackers could do with the credit card information. Though it was stored in encrypted form, it was possible that hackers also obtained the two components needed to descramble the numbers, the company said.

For as many as twothirds of those affected, the exposed data could include mailing addresses, phone numbers, email addresses and passport numbers. Also included might be dates of birth, gender, reservation dates, arrival and departure times and Starwood Preferred Guest account information.

“We fell short of what our guests deserve and what we expect of ourselves,” CEO Arne Sorenson said in a statement. “We are doing everything we can to support our guests and using lessons learned to be better moving forward.”

The breach of personal information could put Marriott in violation of new European privacy laws, as guests included European travelers.

Marriott set up a website and call center for customers who believe they are at risk.

The hackers’ access to the reservation system could be troubling if they turn out to be, say, nation-state spies rather than con artists simply seeking financial gain, said Jesse Varsalone, associate professor of cybersecurity at the University of Maryland University College.

Reservation information could mean knowing when and where government officials are traveling, to military bases, conferences or other destinations abroad, he said.

“There are just so many things you can extrapolate from people staying at hotels,” Mr. Varsalone said.

The richness of the data makes the hack unique, Mr. Wysopal said.

“Once you know someone’s arrival, departure, room preferences,” that could be used to incriminate a person or for a reputation attack that “goes beyond your traditional identity theft or credit-card theft,” he said.