Description: 

Microsoft Defender for DNS is a security feature that provides threat protection for your DNS queries, helping to detect and block malicious activity related to DNS. When Microsoft Defender for DNS is enabled, it monitors your DNS traffic for suspicious patterns, potential data exfiltration, and other security threats, and it provides alerts if it detects any anomalies. This is an essential tool for enhancing the security of your cloud and network infrastructure.

Enabling Microsoft Defender for DNS ensures that your organization’s DNS requests are continuously monitored, providing protection from threats such as domain generation algorithms (DGAs), DNS tunneling, and other attacks that can be carried out over DNS.

Rationale: 

Enabling Microsoft Defender for DNS is critical for securing your organization's DNS infrastructure. By monitoring DNS traffic in real-time, it helps to identify and mitigate threats early, thus preventing potential data breaches or attacks that leverage DNS vulnerabilities. This is crucial for compliance with security standards like SOC 2, HIPAA, NIST, and GDPR, which require proactive security measures for network operations.

Impact: 

When Microsoft Defender for DNS is enabled, it provides real-time threat detection and mitigation against DNS-based attacks. However, enabling this feature might generate additional logs and alerts that need to be monitored and managed. There may be a slight increase in costs associated with monitoring and data storage based on the number of DNS queries processed.

Default Value: 

By default, Microsoft Defender for DNS is disabled and needs to be manually enabled for protection.

Pre-requisites:

  • Azure Subscription: Ensure you have a valid Azure subscription that supports Microsoft Defender for DNS.

  • Permissions: You need Owner or Contributor role permissions to enable Microsoft Defender for DNS.

Remediation:

Automated Steps to Enable Microsoft Defender for DNS:

  1. Sign in to the Azure portal using an account with appropriate permissions.

  2. Navigate to Microsoft Defender for Cloud:

    • In the Azure portal, go to Microsoft Defender for Cloud.

  3. Enable Microsoft Defender for DNS:

    • In the Microsoft Defender for Cloud dashboard, click on Environment settings.

    • Under Subscriptions, select the relevant Subscription where you want to enable Microsoft Defender for DNS.

    • In the Defender plan settings, look for Microsoft Defender for DNS and set the toggle to On.

  4. Configure DNS protection settings:

    • After enabling Microsoft Defender for DNS, review the default settings and ensure that it is integrated with your DNS configurations and network monitoring tools.

    • You can further configure alert thresholds, DNS query monitoring, and traffic analysis options based on your organization's security needs.

  5. Save Settings:

    • Confirm and save the changes. Microsoft Defender for DNS will now actively monitor DNS traffic for security threats and anomalies.

Automated Implementation Using Azure CLI:

To enable Microsoft Defender for DNS using Azure CLI, use the following commands:

az security pricing create --name "Dns" --pricing-tier "Standard"


This command enables Microsoft Defender for DNS on your subscription. You can check the status using:

az security pricing show --name "Dns"


Backout Plan:

To disable Microsoft Defender for DNS:

  1. Sign in to the Azure portal with appropriate permissions.

  2. Navigate to Microsoft Defender for Cloud:

    • Go to Microsoft Defender for Cloud in the Azure portal.

  3. Disable Microsoft Defender for DNS:

    • Under Environment settings, select the relevant Subscription.

    • Disable Microsoft Defender for DNS by toggling it off.

  4. Save Settings:

    • Ensure that the settings are saved and that Microsoft Defender for DNS is no longer active.

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