Daily Blog #590: No Country for Old Unicorns

Unicorns in Office 365 appears to finally be coming to an end - Hacking Exposed Computer Forensics Blog

Hello Reader,
      Well the need to resurrect Unicorns in Office 365 appears to finally be coming to an end. According to the latest Office 365 updated feature notes the default mailbox auditing permissions we all hoped would be there are finally rolling out to everyone.  This means that in

TLDR: Office365 starting 2/1/19 (that's from the action required date on the notice) will start logging all individual mailbox actions for access of mail items into the MailItemsAccessed log but not the Unified Audit Log at this time. The MessageBind action is going away. I just checked my own Office365 deployment and the feature hasn't rolled out to me yet, once it does I'll post about it here and talk about how to pull the data.

From the Updated Feature message:

"To ensure that you have access to critical audit data to investigate security incidents in your organization, we’re making some updates to Exchange mailbox auditing. After this change takes place, Exchange Online will audit mail reads/accesses by default for owners, admins and delegates under the MailItemsAccessed action.
  This message is associated with Microsoft 365 Roadmap ID: 32224.
How does this affect me?
The MailItemsAccessed action offers comprehensive forensic coverage of mailbox accesses, including sync operations. In February 2019, audit logs will start generating MailItemsAccessed audit records to log user access of mail items. If you are on the default configuration, the MailItemsAccessed action will be added to Get-mailbox configurations, under the fields AuditAdmin, AuditDelegate and AuditOwner. Once the feature is rolled out to you, you will see the MailItemsAccessed action added and start to audit reads. This new MailItemsAccessed action is going to replace the MessageBind action; MessageBind will no longer be a valid action to configure, instead an error message will suggest turning on the MailItemsAccessed action. This change will not remove the MessageBind action from mailboxes which have already have added it to their configurations. Initially, these audit records will not flow into the Unified Audit Log and will only be available from the Mailbox Audit Log. We’ll begin rolling this change out in early February, 2019. If you are on the default audit configuration, you will see the MailItemsAccessed action added once the feature is rolled out to you and you start to audit reads.
What do I need to do to prepare for this change?
There is no action you need to take to derive the security benefits of having mail read audit data. The MailItemsAccessed action will be updated in your Get-Mailbox action audit configurations automatically under AuditAdmin, AuditDelegate and AuditOwner. If you have set these configurations before, you will need to update them now to audit the two new mailbox actions. Please click Additional Information for details on how to do this. If you do not want to audit these new actions in your mailboxes and you do not want your mailbox action audit configurations to change in the future as we continue to update the defaults, you can set AuditAdmin, AuditDelegate and AuditOwner to your desired configuration. Even if your desired configuration is exactly the same as the current default configuration, so long as you set the AuditAdmin, AuditDelegate and AuditOwner configurations on your mailbox, you will preclude yourself from further updates to these audit configurations. Please click Additional Information for details on how to do this. If your organization has turned off mailbox auditing, then you will not audit mail read actions."

Also Read: Daily Blog #589

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