Microsoft Defender for Cloud troubleshooting guide

Article
08/29/2024

This guide is for IT professionals, information security analysts, and cloud administrators whose organizations need to troubleshoot problems related to Microsoft Defender for Cloud.

Use the audit log to investigate problems

The first place to look for troubleshooting information is the audit log for the failed component. In the audit log, you can see details like:

Which operations were performed.
Who initiated the operation.
When the operation occurred.
The status of the operation.

The audit log contains all write operations (PUT, POST, DELETE) performed on your resources, but not read operations (GET).

Troubleshoot the Log Analytics agent

Defender for Cloud uses the Log Analytics agent to collect and store data. The information in this article represents Defender for Cloud functionality after transition to the Log Analytics agent.

The alert types are:

Virtual Machine Behavioral Analysis (VMBA)
Network analysis
Azure SQL Database and Azure Synapse Analytics analysis
Contextual information

Depending on the alert type, you can gather the necessary information to investigate an alert by using the following resources:

Security logs in the virtual machine (VM) event viewer in Windows
The audit daemon (auditd) in Linux
The Azure activity logs and the enabled diagnostic logs on the attack resource

You can share feedback for the alert description and relevance. Go to the alert, select the Was This Useful button, select the reason, and then enter a comment to explain the feedback. We consistently monitor this feedback channel to improve our alerts.

Check the Log Analytics agent processes and versions

Just like Azure Monitor, Defender for Cloud uses the Log Analytics agent to collect security data from your Azure virtual machines. After you enable data collection and correctly install the agent in the target machine, the HealthService.exe process should be running.

Open the services management console (services.msc) to make sure that the Log Analytics agent service is running.

To see which version of the agent you have, open Task Manager. On the Processes tab, locate the Log Analytics agent service, right-click it, and then select Properties. On the Details tab, look for the file version.

Check installation scenarios for the Log Analytics agent

There are two installation scenarios that can produce different results when you're installing the Log Analytics agent on your computer. The supported scenarios are:

Agent installed automatically by Defender for Cloud: You can view the alerts in Defender for Cloud and log search. You receive email notifications at the email address that you configured in the security policy for the subscription that the resource belongs to.
Agent manually installed on a VM located in Azure: In this scenario, if you're using agents downloaded and installed manually before February 2017, you can view the alerts in the Defender for Cloud portal only if you filter on the subscription that the workspace belongs to. If you filter on the subscription that the resource belongs to, you won't see any alerts. You receive email notifications at the email address that you configured in the security policy for the subscription that the workspace belongs to.

To avoid the filtering problem, be sure to download the latest version of the agent.

Monitor network connectivity problems for the agent

For agents to connect to and register with Defender for Cloud, they must have access to the DNS addresses and network ports for Azure network resources. To enable this access, take these actions:

When you use proxy servers, make sure that the appropriate proxy server resources are configured correctly in the agent settings.
Configure your network firewalls to permit access to Log Analytics.

The Azure network resources are:

Agent resource	Port	Bypass HTTPS inspection
`*.ods.opinsights.azure.cn`	443	Yes
`*.oms.opinsights.azure.cn`	443	Yes
`*.blob.core.chinacloudapi.cn`	443	Yes
`*.azure-automation.net`	443	Yes

If you're having trouble onboarding the Log Analytics agent, read Troubleshoot Operations Management Suite onboarding issues.

Troubleshoot improperly working antimalware protection

The guest agent is the parent process of everything that the Microsoft Antimalware extension does. When the guest agent process fails, the Microsoft Antimalware protection that runs as a child process of the guest agent might also fail.

Here are some troubleshooting tips:

If the target VM was created from a custom image, make sure that the creator of the VM installed a guest agent.
If the target is a Linux VM, installing the Windows version of the antimalware extension will fail. The Linux guest agent has specific OS and package requirements.
If the VM was created with an old version of the guest agent, the old agent might not have the ability to automatically update to the newer version. Always use the latest version of the guest agent when you create your own images.
Some third-party administration software might disable the guest agent or block access to certain file locations. If third-party administration software is installed on your VM, make sure that the antimalware agent is on the exclusion list.
Make sure that firewall settings and a network security group aren't blocking network traffic to and from the guest agent.
Make sure that no access control lists are preventing disk access.
The guest agent needs sufficient disk space to function properly.

By default, the Microsoft Antimalware user interface is disabled. But you can enable the Microsoft Antimalware user interface on Azure Resource Manager VMs.

Troubleshoot problems with loading the dashboard

If you experience problems with loading the workload protection dashboard, make sure that the user who first enabled Defender for Cloud on the subscription and the user who wants to turn on data collection have the Owner or Contributor role on the subscription. If so, users with the Reader role on the subscription can see the dashboard, alerts, recommendations, and policy.