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Details and results of an automated investigation in Microsoft 365

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When an automated investigation occurs in Microsoft Defender for Office 365, details about that investigation are available during and after the automated investigation process. If you have the necessary permissions, you can view those details in the Microsoft Defender portal. Investigation details provide you with up-to-date status, and the ability to approve any pending actions.

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Check out the new, unified investigation page in the Microsoft Defender portal. To learn more, see (NEW!) Unified investigation page.

Investigation status

The investigation status indicates the progress of the analysis and actions. As the investigation runs, status changes to indicate whether threats were found, and whether actions have been approved.

Status Description
Starting The investigation has been triggered and waiting to start running.
Running The investigation process has started and is underway. This state also occurs when pending actions are approved.
No Threats Found The investigation has finished and no threats (user account, email message, URL, or file) were identified.

TIP: If you suspect something was missed (such as a false negative), you can take action using Threat Explorer.
Partially Investigated The automated investigation found issues, but there are no specific remediation actions to resolve those issues.

The Partially Investigated status can occur when some type of user activity was identified but no cleanup actions are available. Examples include any of the following user activities:


Note: This Partially Investigated status used to be labeled as Threats Found.

The investigation found no malicious URLs, files, or email messages to remediate, and no mailbox activity to fix, such as turning off forwarding rules or delegation.

TIP: If you suspect something was missed (such as a false negative), you can investigate and take action using Threat Explorer
Terminated By System The investigation stopped. An investigation can stop for several reasons:
  • The investigation's pending actions expired. Pending actions time out after awaiting approval for one week
  • There are too many actions. For example, if there are too many users clicking on malicious URLs, it can exceed the investigation's ability to run all the analyzers, so the investigation halts

TIP: If an investigation halts before actions were taken, try using Threat Explorer to find and address threats.
Pending Action The investigation has found a threat, such as a malicious email, a malicious URL, or a risky mailbox setting, and an action to remediate that threat is awaiting approval.

The Pending Action state is triggered when any threat with a corresponding action is found. However, the list of pending actions can increase as an investigation runs. View investigation details to see if other items are still pending completion.
Remediated The investigation finished and all remediation actions were approved (noted as fully remediated).

NOTE: Approved remediation actions can have errors that prevent the actions from being taken. Regardless of whether remediation actions are successfully completed, the investigation status doesn't change. View investigation details.
Partially Remediated The investigation resulted in remediation actions, and some were approved and completed. Other actions are still pending.
Failed At least one investigation analyzer ran into a problem where it couldn't complete properly.

NOTE If an investigation fails after remediation actions were approved, the remediation actions might still have succeeded. View the investigation details.
Queued By Throttling An investigation is being held in a queue. When other investigations complete, queued investigations begin. Throttling helps avoid poor service performance.

TIP: Pending actions can limit how many new investigations can run. Make sure to approve (or reject) pending actions.
Terminated By Throttling If an investigation is held in the queue too long, it stops.

TIP: You can start an investigation from Threat Explorer.

View details of an investigation

  1. Go to the Microsoft Defender portal (https://security.microsoft.com) and sign in.
  2. In the navigation pane, select Actions & submissions > Action center.
  3. On either the Pending or History tabs, select an action. Its flyout pane opens.
  4. In the flyout pane, select Open investigation page.
  5. Use the various tabs to learn more about the investigation.

Certain kinds of alerts trigger automated investigation in Microsoft 365. To learn more, see alert policies that trigger automated investigations.

  1. Go to the Microsoft Defender portal (https://security.microsoft.com) and sign in.
  2. In the navigation pane, select Action center.
  3. On either the Pending or History tabs, select an action. Its flyout pane opens.
  4. In the flyout pane, select Open investigation page.
  5. Select the Alerts tab to view a list of all of the alerts associated with that investigation.
  6. Select an item in the list to open its flyout pane. There, you can view more information about the alert.

Keep the following points in mind

  • Email counts are calculated at the time of the investigation, and some counts are recalculated when you open investigation flyouts (based on an underlying query).

  • The email counts shown for the email clusters on the Email tab and the email quantity value shown on cluster flyout are calculated at the time of investigation, and don't change.

  • The email count shown at the bottom of the Email tab of the email cluster flyout and the count of email messages shown in Explorer reflect email messages received after the investigation's initial analysis.

    Thus, an email cluster that shows an original quantity of 10 email messages would show an email list total of 15 when five more email messages arrive between the investigation analysis phase and when the admin reviews the investigation. Likewise, old investigations might start showing higher counts than Explorer queries show, because data in Microsoft Defender for Office 365 Plan 2 expires after seven days for trials and after 30 days for paid licenses.

    Showing both count historical and current counts in different views is done to indicate the email impact at the time of investigation and the current impact up until the time that remediation is run.

  • In the context of email, you might see a volume anomaly threat surface as part of the investigation. A volume anomaly indicates a spike in similar email messages around the investigation event time compared to earlier timeframes. A spike in email traffic together with certain characteristics (for example, subject and sender domain, body similarity, and sender IP) is typical of the start of email campaigns or attacks. However, bulk, spam, and legitimate email campaigns commonly share these characteristics.

  • Volume anomalies represent a potential threat, and accordingly could be less severe compared to malware or phish threats that are identified using anti-virus engines, detonation, or malicious reputation.

  • You don't have to approve every action. If you don't agree with the recommended action or your organization doesn't choose certain types of actions, then you can choose to Reject the actions or simply ignore them and take no action.

  • Approving and/or rejecting all actions lets the investigation fully close (status becomes remediated), while leaving some actions incomplete results in the investigation status changing to a partially remediated state.

Next steps