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8.7 Use Private Endpoints for Azure Key Vault (Automated)​

note

This rule has been changed to automated, see Automated Policies for CIS Azure 1.5.0 for details.

Profile Applicability​

• Level 2

Description​

Private endpoints secure network traffic from Azure Key Vault to the resources requesting secrets and keys.

Rationale​

Private endpoints will keep network requests to Azure Key Vault limited to the endpoints attached to the resources that are whitelisted to communicate with each other. Assigning the Key Vault to a network without an endpoint will allow other resources on that network to view all traffic from the Key Vault to its destination. In spite of the complexity in configuration, this is recommended for high security secrets.

Impact​

Incorrect or poorly-timed changing of network configuration could result in service interruption. There are also additional costs tiers for running a private endpoint per petabyte or more of networking traffic.

Audit​

From Azure Portal​

  1. From Azure Home open the Portal Menu in the top left.
  2. Select Key Vaults.
  3. Select each Key Vault to be audited.
  4. Select Networking in the left column.
  5. Then select Private Endpoints in the row menu.
  6. View if there is an endpoint attached.

From Azure CLI​

Run the following command within a subscription for each Key Vault you wish to audit.

az keyvault private-endpoint-connection show -g <resourceGroup> --vault-name <keyVaultName>

From Azure Powershell​

Run the following command within a subscription for each Key Vault you wish to audit.

Get-AzPrivateEndpointConnection -PrivateLinkResourceId '/subscriptions/<subscriptionNumber>/resourceGroups/<resourceGroup>/providers/Microsoft.KeyVault/vaults/<keyVaultName>/'

Remediation​

Please see the additional information about the requirements needed before starting this remediation procedure.

From Azure Portal​

  1. From Azure Home open the Portal Menu in the top left.
  2. Select Key Vaults.
  3. Select a Key Vault to audit.
  4. Select Networking in the left column.
  5. Select Private endpoint connections from the top row.
  6. Select + Create.
  7. Select the subscription the Key Vault is within, and other desired configuration.
  8. Select Next.
  9. For resource type select Microsoft.KeyVault/vaults.
  10. Select the Key Vault to associate the Private Endpoint with.
  11. Select Next.
  12. In the Virtual Networking field, select the network to assign the Endpoint.
  13. Select other configuration options as desired, including an existing or new application security group.
  14. Select Next.
  15. Select the private Domain Name System (DNS) for the Private Endpoints.
  16. Select Next.
  17. Optionally add Tags.
  18. Select Next : Review + Create.
  19. Review the information and select Create. Follow the Audit Procedure to determine if it has successfully applied.
  20. Repeat steps 3-19 for each Key Vault.

From Azure CLI​

  1. To create an endpoint, run the following command:
az network private-endpoint create --resource-group <resourceGroup --vnet-name <vnetName> --subnet <subnetName> --name <PrivateEndpointName> --private-connection-resource-id "/subscriptions/<AzureSubscriptionId>/resourceGroups/<resourceGroup>/providers/Microsoft.KeyVault/vaults/<keyVaultName>" --group-ids vault --connection-name <privateLinkConnectionName> --location <azureRegion> --manual-request
  1. To manually approve the endpoint request, run the following command:
az keyvault private-endpoint-connection approve --resource-group <resourceGroup> --vault-name <keyVaultName> -name <privateLinkName>

  1. Determine the Private Endpoint's IP address to connect the Key Vault to the Private DNS you have previously created:

  2. Look for the property networkInterfaces then id; place the value in the variable <privateEndpointNIC> within step 7.

az network private-endpoint show -g <resourceGroupName> -n <privateEndpointName>
  1. Look for the property networkInterfaces then id; place the value on <privateEndpointNIC> in step 7:
az network nic show --ids <privateEndpointName>
  1. Create a Private DNS record within the DNS Zone you created for the Private Endpoint:
az network private-dns record-set a add-record -g <resourcecGroupName> -z "privatelink.vaultcore.azure.net" -n <keyVaultName> -a <privateEndpointNIC>
  1. nslookup the private endpoint to determine if the DNS record is correct:
nslookup <keyVaultName>.vault.azure.net
nslookup <keyVaultName>.privatelink.vaultcore.azure.n

References​

https://docs.microsoft.com/en-us/azure/private-link/private-endpoint-overview
https://docs.microsoft.com/en-us/azure/storage/common/storage-private-endpoints
https://azure.microsoft.com/en-us/pricing/details/private-link/
https://docs.microsoft.com/en-us/azure/key-vault/general/private-link-service?tabs=portal
https://docs.microsoft.com/en-us/azure/virtual-network/quick-create-portal
https://docs.microsoft.com/en-us/azure/private-link/tutorial-private-endpoint-storage-portal
https://docs.microsoft.com/en-us/azure/bastion/bastion-overview
https://docs.microsoft.com/azure/dns/private-dns-getstarted-cli#create-an-additional-dns-record
https://docs.microsoft.com/en-us/security/benchmark/azure/security-controls-v3-data-protection#dp-8-ensure-security-of-key-and-certificate-repository

Additional Information​

This recommendation assumes that you have created a Resource Group containing a Virtual Network that the services are already associated with and configured private DNS. A Bastion on the virtual network is also required, and the service to which you are connecting must already have a Private Endpoint. For information concerning the installation of these services, please see the attached documentation.

Microsoft's own documentation lists the requirements as: A Key Vault. An Azure virtual network. A subnet in the virtual network. Owner or contributor permissions for both the Key Vault and the virtual network.

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