Microsoft AzureOverview
[NOTE: As of August 1, 2023, customers with an existing subscription to Defender for DNS can continue to use the service, but new subscribers will receive alerts about suspicious DNS activity as part of Defender for Servers P2.]
Microsoft Defender for DNS scans all network traffic exiting from within a subscription.
Rationale
DNS lookups within a subscription are scanned and compared to a dynamic list of websites with potential security threats. These threats could result from a security breach within your services, so scanning for them could prevent a potential security threat from being introduced.
Impact
Enabling Microsoft Defender for DNS requires enabling Microsoft Defender for your subscription. Both will incur additional charges, with Defender for DNS being a small amount per million queries.
Remediation guidance
From Azure Console
- Open Microsoft Defender for Cloud | Environment settings
- Select a subscription
- Under
Settings, selectDefender plans - For
DNS, selectOnforStatus - Select Save
Using Azure Command Line Interface
az security pricing create -n 'DNS' --tier 'Standard'
Using Azure PowerShell
Set-AzSecurityPricing -Name 'DNS' -PricingTier 'Standard'
Default Value
By default, Microsoft Defender for DNS is not enabled.
References
- https://azure.microsoft.com/en-us/pricing/details/defender-for-cloud/
- https://learn.microsoft.com/en-us/security/benchmark/azure/baselines/dns-security-baseline
- https://learn.microsoft.com/en-us/azure/defender-for-cloud/defender-for-dns-alerts
- https://learn.microsoft.com/en-us/azure/defender-for-cloud/enable-enhanced-security
- https://learn.microsoft.com/en-us/azure/defender-for-cloud/alerts-overview
- https://learn.microsoft.com/en-us/security/benchmark/azure/security-controls-v3-network-security#ns-10-ensure-domain-name-system-dns-security
- https://learn.microsoft.com/en-us/security/benchmark/azure/security-controls-v3-logging-threat-detection#lt-1-enable-threat-detection-capabilities
Multiple Remediation Paths
Azure
SERVICE-WIDE (RECOMMENDED when many resources are affected): Assign Azure Policy initiatives at management group/subscription scope and trigger remediation tasks.
az policy assignment create --name <assignment-name> --scope /subscriptions/<subscription-id> --policy-set-definition <initiative-id>
az policy remediation create --name <remediation-name> --policy-assignment <assignment-id>
ASSET-LEVEL: Apply the resource-specific remediation steps above to the listed non-compliant resources.
PREVENTIVE: Embed Azure Policy checks into landing zones and IaC workflows to block or auto-remediate drift.
References for Service-Wide Patterns
- Azure Policy overview: https://learn.microsoft.com/en-us/azure/governance/policy/overview
- Azure Policy remediation: https://learn.microsoft.com/en-us/azure/governance/policy/how-to/remediate-resources
- Azure Policy initiative structure: https://learn.microsoft.com/en-us/azure/governance/policy/concepts/initiative-definition-structure
Operational Rollout Workflow
Use this sequence to reduce risk and avoid repeated drift.
1. Contain at Service-Wide Scope First (Recommended)
- Azure: assign policy initiatives at management group/subscription scope and run remediation tasks.
az policy assignment create --name <assignment-name> --scope /subscriptions/<subscription-id> --policy-set-definition <initiative-id>
az policy remediation create --name <remediation-name> --policy-assignment <assignment-id>
2. Remediate Existing Affected Assets
- Execute the control-specific Console/CLI steps documented above for each flagged resource.
- Prioritize internet-exposed and production assets first.
3. Validate and Prevent Recurrence
- Re-scan after each remediation batch.
- Track exceptions with owner and expiry date.
- Add preventive checks in IaC/CI pipelines.
Query logic
These are the stored checks tied to this control.
Azure Subscriptions without Microsoft Defender for DNS
Connectors
Covered asset types
Expected check: eq []
{
connectors(
where: { pricing_SOME: { name: "Dns", pricingTier: "Free" } }
) {
...AssetFragment
}
}
