Description:

 Using Private Endpoints for Azure Key Vault ensures that all communication between clients and the Key Vault service occurs over a private network, rather than through the public internet. Private Endpoints allow Azure resources to connect to Key Vault via a private IP address within your Virtual Network (VNet), significantly reducing exposure to the public internet and improving security by ensuring that traffic remains within Azure’s trusted network.

Rationale:

 Enabling Private Endpoints for Azure Key Vault enhances the security of your sensitive data by preventing unauthorized access from the public internet. It ensures that key management operations (e.g., accessing secrets or cryptographic keys) happen within a secure, isolated network environment. This practice is essential for compliance with security regulations such as SOC 2, HIPAA, GDPR, and NIST, which require securing sensitive information and limiting exposure to external networks.

Impact: 

Using Private Endpoints for Azure Key Vault improves the security posture by limiting traffic to the private network and eliminating the potential risks associated with public IP exposure. However, this may require updating DNS configurations and ensuring that all client applications are able to communicate with the private endpoint within the VNet. Some legacy systems may require modification to use private network access, which could introduce complexity.

Default Value:

 By default, Azure Key Vault is accessible over the public internet unless Private Endpoints are explicitly configured and enabled.

Pre-requisites:

  • Azure Key Vault: Ensure that the Key Vault instance exists and is properly configured.

  • Virtual Network (VNet): Ensure that the Key Vault has access to a Virtual Network with appropriate subnet configuration for Private Endpoints.

  • DNS Configuration: Ensure that DNS resolution is properly configured to route traffic to the private endpoint.

  • Permissions: You need appropriate permissions, such as Owner or Contributor, to deploy and configure Private Endpoints for Key Vault.

Remediation:

Audit:

To check if Private Endpoints are configured for your Azure Key Vault:

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

  2. Navigate to the Azure Key Vault:

    • In the Azure portal, go to Key Vaults and select the relevant Key Vault.

  3. Check Private Endpoint Configuration:

    • In the left-hand menu, click on Networking.

    • Under the Private Endpoint connections section, check if there are any active Private Endpoints configured.

    • Verify that the Private Endpoint is connected to the appropriate Virtual Network and subnet.

Automated Implementation:

To ensure that Private Endpoints are used for Azure Key Vault across your organization, you can use Azure Policy to enforce the configuration.

  1. Create a custom Azure Policy to ensure Private Endpoints are used for all Azure Key Vault instances:

    • Go to the Azure portal.

    • Navigate to Policy and click on Definitions.

    • Create a new Custom Policy with the following content:

{
  "properties": {
    "displayName": "Ensure Private Endpoints Are Used for Azure Key Vault",
    "policyType": "Custom",
    "mode": "All",
    "description": "This policy ensures that Azure Key Vault is only accessible through Private Endpoints and not through the public internet.",
    "parameters": {},
    "metadata": {
      "version": "1.0.0",
      "category": "Networking"
    },
    "policyRule": {
      "if": {
        "field": "Microsoft.KeyVault/vaults/networkAcls.defaultAction",
        "equals": "Allow"
      },
      "then": {
        "effect": "deny"
      }
    }
  }
}


  1. Assign the policy:

    • After creating the custom policy, assign it to the relevant subscriptions or resource groups to ensure that Private Endpoints are used for Azure Key Vault instances.

Backout Plan:

To revert the setting (though this is not recommended for security reasons):

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

  2. Navigate to the Azure Key Vault:

    • In the Key Vault settings, go to Networking.

  3. Remove Private Endpoint:

    • Disconnect or delete any existing Private Endpoints.

  4. Allow Public Access:

    • Set the network access rule to Allow public access if required.

If the setting was enforced via Azure Policy, modify or remove the policy to allow non-Private Endpoint access.

References: