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How To Fix A Compromised (Hacked) Microsoft 365 Account

ā€‹The dreaded moment you realize that your Microsoft 365 account has been compromised can be frustrating and we are seeing it more and more everyday. Hackers are learning and growing in the avenues they take to steal accounts. Since Microsoft 365 accounts are controlled by a username and password, once a bad actor has access to those credentials and can login as the user, the account is considered compromised. At that point, the hacker can login to every aspect of the Microsoft 365 account: mailbox, SharePoint, OneDrive, etc., and even send emails on the account owners behalf to internal and external contacts. Yikes!

In the world today, it will always be best to try to keep the tenant and users as secure as possible, especially with the new ways that hackers have to obtain account credentials. There are many things that can be done in the instance of a compromised account, as well as things that can be applied to help prevent this from happening again. Here are the steps to take upon realization of a compromised account:

  1. Reset Account Password - This is a big one. Resetting the password is the absolute first thing that should be done. The reason the hacker has access in the first place is because he gained access to the password, so resetting it will ensure that he does not have access anymore. It's important to note that in the event of a breach the new password should be vastly different than the old one.
  2. Remove Account From All Administrator Roles - If the account is an admin or in any admin role groups, it can be removed until it is ensured that the account is not compromised any longer. If the attacker gains admin access, there are many other things that they can do within the entire Microsoft 365 tenant, and that could be very bad news.
  3. Sign Out of All Sessions - This is something that is overlooked, but to completely ensure that the hacker does not have access to anything, all sessions need to be ended.
  4. Check/Disable Mailbox Rules - Most of the time, hackers will apply specific rules on the account to break the mail flow. We see this VERY often and it always needs to be looked at when fixing a breached account
  5. Check/Disable Mail Forwarding - By default, Microsoft has Mail Forwarding turned off, but it is very important to check this with a breached account. A lot of times, hackers will enable this feature on the account to send all mail straight to their account while the user has no idea. This can be disabled and the forwarding addresses can be removed.
  6. Enable Multi-Factor Authentication (MFA) - MFA is becoming the norm when it comes to email security and should be adopted everywhere. This would stop most hackers in their tracks and ensures that identity is verified upon each sign-in attempt by send a secure code to the actual account owner.
At RyanTech, we always say that it is better to be precautionary as opposed to reactionary and we can help with and recommend things that can help to prevent breaches from happening in the first place. As a business with sensitive information stored in the cloud, it's best to take a look at how you can lock down and secure the tenant and user accounts in the most productive way, so reach out to us if you have questions on what can be done or if you would like to start applying precautionary measures.
For preventing unwanted access to accounts, we recommend looking at Cloud Protect to detect breaches and have our team of security experts review your account alerts: ryantechinc.com/landing/cloud-protect

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