In September, Marriott International received an alert from an internal security tool regarding an attempt to access the Starwood guest reservation database. Marriott learned during the investigation that there had been unauthorized access to the Starwood network, which had occurred since 2014.
The information copied from the guest reservation database includes information about guests who made a reservation at a StarwoodOpens in New Window property. The combination of information varies by guest. For some individuals, the information copied also included payment card numbers and payment card expiration dates, but the payment card numbers were encrypted using Advanced Encryption Standard encryption (AES-128).
There are two components needed to decrypt the payment card numbers, and at this point Marriott has not been able to rule out the possibility that both were taken.
After receiving the internal security alert, Marriott engaged leading security experts to help determine what occurred. They installed additional security tools to help gather facts and reported the incident to law enforcement. Their internal and external security teams have been working nonstop to investigate the incident, implement additional security measures, and address what was found.