Cis Azure Foundations 8.1.9.1

8.1.9.1 Ensure That Microsoft Defender for DNS Is Set To 'On' (Automated)

Description

Enable Microsoft Defender for DNS to provide an additional layer of protection for DNS queries, detecting suspicious activities and threats targeting the DNS layer of Azure resources.

Rationale

Microsoft Defender for DNS provides protection by continuously monitoring all DNS queries from Azure resources. It detects suspicious activities such as DNS tunneling, communication with known malicious domains, and DNS attacks. This helps organizations identify compromised resources and potential data exfiltration attempts through DNS channels.

Impact

Enabling Microsoft Defender for DNS incurs additional costs per million DNS queries. Organizations with high volumes of DNS queries should evaluate costs before enabling. Note that Microsoft has announced deprecation plans for this standalone plan as DNS protection is being integrated into Defender for Servers.

Audit Procedure

From Azure Portal:

1. Go to Microsoft Defender for Cloud.
2. Under Management, click Environment settings.
3. Click the name of a subscription.
4. Select the Defender plans blade.
5. Locate DNS in the list and ensure the Status is set to On.

From Azure CLI:

az security pricing show -n Dns --query pricingTier

Ensure "Standard" is returned.

From PowerShell:

Get-AzSecurityPricing -Name Dns | Select-Object PricingTier

Ensure Standard is returned.

Expected Result

The pricing tier for Dns should be Standard.

Remediation

From Azure Portal:

1. Go to Microsoft Defender for Cloud.
2. Under Management, click Environment settings.
3. Click the name of a subscription.
4. Select the Defender plans blade.
5. In the row for DNS, set the Status toggle to On.
6. Click Save.

From Azure CLI:

az security pricing create -n Dns --tier Standard

From PowerShell:

Set-AzSecurityPricing -Name Dns -PricingTier Standard

Default Value

Microsoft Defender for DNS is disabled (Free tier) by default.

References

1. https://learn.microsoft.com/en-us/azure/defender-for-cloud/defender-for-dns-introduction
2. https://learn.microsoft.com/en-us/azure/defender-for-cloud/enable-enhanced-security
3. https://azure.microsoft.com/en-us/pricing/details/defender-for-cloud/#pricing
4. https://learn.microsoft.com/en-us/cli/azure/security/pricing
5. https://learn.microsoft.com/en-us/powershell/module/az.security/set-azsecuritypricing

Profile

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