NCSC advice for Marriott International customers

Created:  30 Nov 2018
Updated:  30 Nov 2018
Advice for customers of Marriott International following the reports of a data breach.

Who is this guidance for?

Customers of the hotel group, Marriott International who may find their personal details on the organisation’s guest reservation database which is managed by Starwood.


Marriott has confirmed that an internal investigation has found that an attacker would have had access to the Starwood guest reservation database since 2014, affecting up to an estimated 500m customers. Marriott has also confirmed that it will be contacting customers who have been affected by the breach.

What should I do?

You can read Marriott International’s latest information here.

If you have made a reservation with Marriott International since 2014, the period in which their internal investigation has highlighted, then we recommend that you contact your bank/credit card provider if you have noticed any irregular activity. You should also monitor your financial accounts for any suspicious transactions.

At present, there is no indication that customers’ Marriott online account details ie usernames and passwords have been lost.

You may want to visit Get Safe Online which hosts a lot of information on protecting yourself and your data online. It may also be a good opportunity to visit ‘have I been pwned’ (or other similar services) which can alert you to whether your details have been leaked or not.

It’s also good practice to use two-factor authentication on your sensitive accounts and the NCSC recommends that you have unique passwords for all of your accounts.

Those affected should remain vigilant against suspicious phone calls or targeted emails. Further guidance on this and other cyber security matters can be found here on the NCSC website and Cyber Aware.

If members of the public think they have been a victim of online crime they can report a cyber incident using Action Fraud’s online fraud reporting tool anytime of the day or night or call 0300 123 2040. For further information visit

For further information, look at NCSC guidance on the phishing threat following data breaches.

What else do I need to know?

Marriott International has opened a dedicated call centre to answer customer’s questions around this incident. They have also been issuing emails on a rolling basis to affected guests whose email addresses are in the Starwood guest reservation database.

Details for the above and any further updates from Marriott International can be found here.

You can keep track of the NCSC’s latest statement here.

Genuine financial institutions will not ask you to reply to an email with personal information, or details about your account. If you contact them, use a phone number/email address you have looked up yourself, rather than one sent to you in the email – it may be false.


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