Overview of automated investigations

  • 4 minutes to read

Microsoft Defender Advanced Threat Protection (Microsoft Defender ATP) offers a wide breadth of visibility on multiple machines. With this kind of optics, the service generates a multitude of alerts. The volume of alerts generated can be challenging for a typical security operations team to individually address. To address this challenge, Microsoft Defender ATP uses automated investigation and remediation capabilities to significantly reduce the volume of alerts that must be investigated individually.

The automated investigation feature leverages various inspection algorithms, and processes used by analysts (such as playbooks) to examine alerts and take immediate remediation action to resolve breaches. This significantly reduces alert volume, allowing security operations experts to focus on more sophisticated threats and other high value initiatives. The Automated investigations list shows all the investigations that were initiated automatically, and includes details, such as status, detection source, and when the investigation was initiated.

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How the automated investigation starts

When an alert is triggered, a security playbook goes into effect. Depending on the security playbook, an automated investigation can start. For example, suppose a malicious file resides on a machine. When that file is detected, an alert is triggered. The automated investigation process begins. Microsoft Defender ATP checks to see if the malicious file is present on any other machines in the organization. Details from the investigation, including verdicts (Malicious, Suspicious, and Clean) are available during and after the automated investigation.

Note

Currently, automated investigation only supports the following OS versions:

  • Windows Server 2019
  • Windows 10, version 1709 (OS Build 16299.1085 with KB4493441) or later
  • Windows 10, version 1803 (OS Build 17134.704 with KB4493464) or later
  • Later versions of Windows 10

Details of an automated investigation

During and after an automated investigation, you can view details about the investigation. Selecting a triggering alert brings you to the investigation details view where you can pivot from the Investigation graph, Alerts, Machines, Evidence, Entities, and Log tabs.

Tab Description
Alerts Shows the alert that started the investigation.
Machines Shows where the alert was seen.
Evidence Shows the entities that were found to be malicious during the investigation.
Entities Provides details about each analyzed entity, including a determination for each entity type (Malicious, Suspicious, or Clean).
Log Shows the chronological detailed view of all the investigation actions taken on the alert.
Pending actions If there are pending actions on the investigation, the Pending actions tab will be displayed where you can approve or reject actions.

Important

Go to the Action center to get an aggregated view all pending actions and manage remediation actions. The Action center also acts as an audit trail for all automated investigation actions.

How an automated investigation expands its scope

While an investigation is running, any other alerts generated from the machine are added to an ongoing automated investigation until that investigation is completed. In addition, if the same threat is seen on other machines, those machines are added to the investigation.

If an incriminated entity is seen in another machine, the automated investigation process will expand its scope to include that machine, and a general security playbook will start on that machine. If 10 or more machines are found during this expansion process from the same entity, then that expansion action will require an approval and will be seen in the Pending actions view.

How threats are remediated

Depending on how you set up the machine groups and their level of automation, the automated investigation will either require user approval (default) or automatically remediate threats.

You can configure the following levels of automation:

Automation level Description
No automated response Machines do not get any automated investigations run on them.
Semi - require approval for any remediation This is the default automation level.

An approval is needed for any remediation action.
Semi - require approval for non-temp folders remediation An approval is required on files or executables that are not in temporary folders.

Files or executables in temporary folders, such as the user's download folder or the user's temp folder, will automatically be remediated if needed.
Semi - require approval for core folders remediation An approval is required on files or executables that are in the operating system directories such as Windows folder and Program files folder.

Files or executables in all other folders will automatically be remediated if needed.
Full - remediate threats automatically All remediation actions will be performed automatically.

Tip

For more information on how to configure these automation levels, see Create and manage machine groups.

The default machine group is configured for semi-automatic remediation. This means that any malicious entity that calls for remediation requires an approval and the investigation is added to the Pending actions section. This can be changed to fully automatic so that no user approval is needed.

When a pending action is approved, the entity is then remediated and this new state is reflected in the Entities tab of the investigation.

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