This Oct. 5, 2010 file photo shows the exterior of a Marriott hotel in Santa Clara, Calif. Marriott says that fewer guest records were involved in a previously announced data breach than it initially disclosed. The lodging company said Friday, Jan. 4, 2019, that it now believes that the number of potentially involved guests is lower than the 500 million originally estimated. (AP Photo/Paul Sakuma, File) Marriott says fewer guest records were compromised than feared in a previously announced data breach.
But the largest hotel chain in the world confirmed Friday that approximately 5.25 million unencrypted passport numbers were accessed.
The compromise of those passport numbers has raised alarms among security experts because, combined with names, addresses and other personal information, they can be used to open fraudulent accounts, or be used by foreign operators.
The FBI is leading the investigation of the hack and investigators suspect the hackers were working on behalf of the Chinese Ministry of State Security.
The hackers accessed about 20.3 million encrypted passport numbers. There is no evidence that they were able to use the master encryption key required to gain access to that data.
Explore further: Marriott security breach exposed data of up to 500M guests (Update)