If you stayed at an MGM Resorts hotel in the few years up to and including 2017, the best thing to do would be to diligently get a free credit report every four months using. ZDNet was able to confirm the validity of several records by contacting the individuals named via the phone numbers and email addresses listed in the data.
It's not clear when the data was stolen, but ZDNet, which was tipped off about the posting of the data on the hacking forum and then analyzed the data with the help of security firm Under the Breach, has concluded that none of the data was collected after 2017.