Someone has hacked into our Microsoft 365 account.

Donna C 0 Reputation points
2026-10-08T23:27:14.4533333+00:00

Someone from Indonesia has hacked into our Microsoft 365 account. It got messy, got access to credit cards, airline mileage accounts and so on. We've done all the cleansing, new accounts, new cards, new passwords, loaded new security programs, and emails but his device continues to show up under signed on devices. He no longer shows up under sign on activity but yet under the subscription tab, his devices keeps popping back up every other day or so as a signed on device. Spoke in length with Microsoft on this subject and they feel there is no threat but we just want to figure out how to rid his device once and for all. Short of just cancelling our 365 account, there has to be a way to rid him from our subscription account.

Thank you,

Microsoft 365 and Office | Subscription, account, billing | For home | Windows
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  1. Xavier-D 13,865 Reputation points Microsoft External Staff Moderator
    2026-10-09T04:14:41.4166667+00:00

    Hello Donna C,

    I’m sorry you have had to deal with such a serious account compromise.

    Since the unfamiliar device keeps returning, removing it from the device list alone may not fully sign it out of the account.

    Please try these steps:

    1. Open Advanced security options, sign in with the affected Microsoft account, scroll down to Sign out everywhere, and select Sign out. It may take up to 24 hours to sign the account out of browsers and apps.
    2. Open the Microsoft 365 Installs page. Under Devices, find the unfamiliar device and select Sign out of Microsoft 365 or Office. Microsoft 365 or Office may take up to 72 hours to process the remote sign-out.
    3. Open the Microsoft account Devices page and remove the unfamiliar device again.
    4. Review the account’s security information and confirm that all email addresses, phone numbers, aliases, and verification methods belong to you. Also ensure that two-step verification is enabled and that the new password is unique.

    For additional guidance, see: How to sign out of your Microsoft account everywhere

    Feel free reply back to this post if you need further assistance, I'll be happy to help.

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