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8.3.8 Ensure Private Endpoints are used to access Azure Key Vault

Information

Use private endpoints to allow clients and services to securely access data located over a network via an encrypted Private Link. To do this, the private endpoint uses an IP address from the VNet for each service. Network traffic between disparate services securely traverses encrypted over the VNet. This VNet can also link addressing space, extending your network and accessing resources on it. Similarly, it can be a tunnel through public networks to connect remote infrastructures together. This creates further security through segmenting network traffic and preventing outside sources from accessing it.

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

Securing traffic between services through encryption protects the data from easy interception and reading.

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.

Solution

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

Remediate from Azure Portal

 - From Azure Home open the Portal Menu in the top left.
 - Select Key Vaults.
 - Select a Key Vault to audit.
 - Select Networking in the left column.
 - Select Private endpoint connections from the top row.
 - Select + Create.
 - Select the subscription the Key Vault is within, and other desired configuration.
 - Select Next.
 - For resource type select Microsoft.KeyVault/vaults.
 - Select the Key Vault to associate the Private Endpoint with.
 - Select Next.
 - In the Virtual Networking field, select the network to assign the Endpoint.
 - Select other configuration options as desired, including an existing or new application security group.
 - Select Next.
 - Select the private DNS the Private Endpoints will use.
 - Select Next.
 - Optionally add Tags.
 - Select Next : Review + Create.
 - Review the information and select Create . Follow the Audit Procedure to determine if it has successfully applied.
 - Repeat steps 3-19 for each Key Vault.

Remediate from Azure CLI

 - 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/<AZURE SUBSCRIPTION ID>/resourceGroups/<resourceGroup>/providers/Microsoft.KeyVault/vaults/<keyVaultName>" --group-ids vault --connection-name <privateLinkConnectionName> --location <azureRegion> --manual-request
 - To manually approve the endpoint request, run the following command:

az keyvault private-endpoint-connection approve --resource-group <resourceGroup> --vault-name <keyVaultName> -name <privateLinkName>
 -

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

 -

Look for the property networkInterfaces then id; the value must be placed in the variable <privateEndpointNIC> within step 7.

az network private-endpoint show -g <resourceGroupName> -n <privateEndpointName>
 - Look for the property networkInterfaces then id; the value must be placed on <privateEndpointNIC> in step 7.

az network nic show --ids <privateEndpointName>
 - 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>
 - nslookup the private endpoint to determine if the DNS record is correct:

nslookup <keyVaultName>.vault.azure.net
nslookup <keyVaultName>.privatelink.vaultcore.azure.n

Impact:

If an Azure Virtual Network is not implemented correctly, this may result in the loss of critical network traffic.

Private endpoints are charged per hour of use. Refer to https://azure.microsoft.com/en-us/pricing/details/private-link/ and https://azure.microsoft.com/en-us/pricing/calculator/ to estimate potential costs.

See Also

https://workbench.cisecurity.org/benchmarks/21611

Item Details

Category: CONFIGURATION MANAGEMENT, CONTINGENCY PLANNING, PLANNING, PROGRAM MANAGEMENT, SYSTEM AND SERVICES ACQUISITION, SYSTEM AND COMMUNICATIONS PROTECTION

References: 800-53|CM-7, 800-53|CP-6, 800-53|CP-7, 800-53|PL-8, 800-53|PM-7, 800-53|SA-8, 800-53|SC-7, CSCv7|14.1

Plugin: microsoft_azure

Control ID: ff4565fcea2b58ce5970c644c22445f8f316a490b3611b596a19ef81ef555d84