MGM Resorts shuts down online systems after cyberattack

• MGM runs some of the most well-known Vegas hotel brands, including the Bellagio, Mandalay Bay and Excalibur.

What they're saying: "MGM Resorts recently identified a cybersecurity issue affecting some of the Company's systems," the company wrote in an online post.

• "Promptly after detecting the issue, we quickly began an investigation with assistance from leading external cybersecurity experts."

Details: Alongside room keys and slot machines, the cyberattack also took down the websites for several MGM properties. Visitors are now being directed to a list of phone numbers for affected properties to call instead.

• The MGM Rewards App, where guests can access their digital room keys and trip information, is also offline as of Monday evening, Axios confirmed.
• MGM did not immediately respond to an emailed request for comment, but it's also unclear if employees currently have access to their internal systems.

Between the lines: It remains unclear how long it will take MGM to bring its systems back online and how hackers were able to infiltrate the company's networks.

• It often can take days or weeks for companies to determine the full extent of a cyberattack on their networks.

Flashback: Hackers steal personal data of 10.6M MGM guests