Investigate Microsoft Defender for Cloud alerts using Azure Sentinel

Published Dec 14 2020 01:05 PM 6,659 Views

Microsoft Defender for Cloud performs continuous assessment of your cloud workloads and provides the recommendations concerning the security of the environment. Microsoft Defender for Cloud covers scenarios by offering Cloud Security Posture Management (CSPM) and Cloud Workload Protection Platform (CWPP) capabilities (read this article for more details). 

 

To cover the threat detections for the CWPP scenario you need to upgrade Microsoft Defender for Cloud to Extended security features. Defender for Cloud with all enhanced security features uses a variety of detection capabilities to alert you of potential threats to your environment. Microsoft Defender’s threat protection includes fusion kill-chain analysis, which automatically correlates alerts in your environment based on cyber kill-chain analysis, to help you better understand the full story of an attack campaign. The alerts can tell you what triggered the alert, what in your environment was targeted, the source of the attack, and remediation steps. You also have the flexibility to set up custom alerts to address specific needs in your environment. 

 

Azure Sentinel is a cloud-native Security Information and Event Management (SIEM) and Security Orchestration, Automation and Response (SOAR) solution. Azure Sentinel’s role is to ingest data from many sources and correlate the information across all of those sources. On top of that, Azure Sentinel leverages intelligent security analytics and threat intelligence to help with alert detection, threat visibility, proactive hunting, and threat response.  

 

When  Defender for Cloud plans detects/triggers alerts, you can stream these alerts to your own SIEM solutionBy doing this you can quickly view what needs your attention from one management interface and take an appropriate action. 

 

In this blog, we will walk you through how alerts from Microsoft Defender integrates with Sentinel providing Sentinel with security recommendations, alerts, and analytics. When integrated together how they operate in a better together scenario. 

 

Integration 

Azure Sentinel leverages data connectors which give you that holistic rich view across multiple data sources. To stream Microsoft Defender alerts in to Azure Sentinel, the first step is to configure this integration by adding Microsoft Defender for Cloud connector. You can connect to Microsoft Defender for Cloud data connector by following the steps from this article. 

After following the steps from the article mentioned in the previous paragraph, you can confirm the connectivity (as shown in the figure below). 

Image 1: Confirming the connectivity of Microsoft Defender for Cloud connector in Azure SentinelImage 1: Confirming the connectivity of Microsoft Defender for Cloud connector in Azure Sentinel

Investigating an Microsoft Defender alert in Azure Sentinel

In this example, we are analyzing an alert which is using Fusion analytics that automatically correlates alerts in the environment based on cyber kill-chain analysis to help better understand the full attack surface as to where it started and what kind of impact it had on the resources. To learn more about Cloud smart alert correlation (also known as fusion), please read our documentation here.

Screenshot 2021-10-31 211807.png

Screenshot 2021-10-31 211908.png

As you notice in image 3, Fusion technology has correlated different severity alerts and contextual signals together.

The left pane of the security incident page shows high-level information about the security incident like, alert description, severity, activity time and affected resources. The right pane of security incident page contains information about the Alerts and their description.

Screenshot 2021-10-31 211934.png

Switch to the Take Action tab (as shown in Image 4) to know more information on how to Mitigate the threat, review the related recommendations identified on this affected resource under prevent future attacks.

 

Trigger automated response option will provide you the option to trigger a Logic App as a response to this security alert. Setting up an automation reduces overhead and helps you take care of incidents automatically and quickly. Review our Github repository to find different automation artifacts that you can leverage to resolve the alerts or recommendations in Security Center.

 

Suppress similar alerts option gives you an option to suppress future alerts with similar characteristics if alert isn’t relevant for your organization. Please review this article to understand how you can benefit from this feature.

 

To further investigate this alert, let’s navigate to Azure Sentinel. One of the benefits of triaging incidents in Azure Sentinel is that you can start from a holistic high-level view and zoom in on relationships, often found in related entities or notable events. Azure Sentinel helps you in identifying and correlating those in a couple of ways. In addition, Azure Sentinel offers powerful hunting capabilities to find that needle in the haystack.

In this blogpost, we will provide a couple of examples of those options.

 

Triaging the Microsoft Defender incident in Azure Sentinel

When we pivot over the Azure Sentinel, we can see the same incidents appearing in our triage view:

Image 5: Incidents pane of Azure SentinelImage 5: Incidents pane of Azure Sentinel

Looking at the details of our incident, we can see the affected entities and can start our investigations from there, or we can pivot over to the sending source, in our case Microsoft Defender for Cloud:

 

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When we look more closer, we quickly see that more sources are reporting suspicious activities related to our affected entities, which we need to investigate:

Image 6: Example of Open incidents from Azure SentinelImage 6: Example of Open incidents from Azure Sentinel

We can run investigations in several ways, one is a visual investigation:

Zooming in on our suspicious entity, our server, we can see a lot more to investigate, including a timeline of events:

Image 8: Timelines of eventsImage 8: Timelines of events

This is a clear signal that this is a true positive which we should be escalating for further investigation. We can add our findings to the incident comment section and take a couple of counter measures to isolate our servers by leveraging a block IP action which we have discovered as being a malicious IP address. You can find the Logic App playbook here. This playbook has been authored to block a brute force attack IP address, but can also be used to block any IP address.

In our investigation we also saw that an Azure Active Directory user was affected:

Image 9: Azure Active Directory user that was affectedImage 9: Azure Active Directory user that was affected

The second preventive counter measure we will take is to confirm that this is a risky user, by leveraging a confirm risky user playbook and reset the user’s password.

Before we escalate the incident to our investigations team, we create a ticket in ServiceNow, add our findings to the incident comments and continue our triage.

 

A usual question we receive at this point is, "When I use the Microsoft Defender for Cloud data connector in Azure Sentinel and generate Incidents, what happens when I close my Azure Sentinel Incident, does it close the related Microsoft Defender for Cloud alert?"

The short of this is it does not. The Azure Sentinel Incident closes, but the ASC Alert remains active. Some customers prefer to keep the alerts active in ASC, while they are closing the incident in Azure Sentinel and some of our customers prefer to close the incident or alerts at both ends. You also have the option to suppress the ASC Alert manually in the ASC Portal. If the outcome of your incident triage is complete and you decide to close the incident in Azure Sentinel, you can use and invoke this Logic App Playbook which will close the incident in Azure Sentinel and dismisses the alert in Microsoft Defender for Cloud. This article describes how to run a Logic App Playbook. Azure Sentinel also allows you to invoke a Logic App Playbook automatically upon creation of an incident, which is described here.

 

Hope you enjoyed learning our better together story of Microsoft Defender for Cloud and Azure Sentinel.

 

Acknowledgements

This blog was written in collaboration with my super talented colleague Tiander Turpijn, Senior Program Manager and reviewed by Yuri Diogenes, Principal PM Manager

 

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