Azure Key Vault Governance using Azure Policy

The right tool to ensure that you have control of your cloud environment and resources is Cloud Governance. Today’s post talks about how we can govern our Azure Key Vault instance(s) using Azure Policy.

Azure Key Vault: is a cloud service for securely storing and accessing secrets. A secret is anything that you want to tightly control access to, such as API keys, passwords, certificates, or cryptographic keys.

Azure Policy is a service in Azure that allows you to create policies that enforce and control the properties of a resource. When these policies are used, they enforce different rules and effects over your resources, so those resources stay compliant with your IT governance standards.

Starting today, the integration of Azure Policy with Azure Key Vault (KV) is in GA (General Availability), meaning that we can use it for production environments from all public Azure Regions.

How Azure Policy can help us?

Imagine that you are part of an organization where Azure Key Vault is the main Vault used to store secrets and certifications. The no. of tools used by the organization is high (400+), and not all of them are integrated with Azure AD and Single-Sign-On.

The cyber-security team is looking for a mechanism that would:

• Enforce that secret (e.g., passwords) are rotated every 90 days (expires)
• A tool to notify the teams that a secret expires in 7 days
• The key allowed for encryption is RSA — HSM only or ECC — HSM
• The key should have a minimum key size
• The key validity period is a maximum of 180 days.
• The certification authority is limited only to a specific authority
• The certification expires after 356 days
• A mechanism to notify the teams that the certificate expires in a 30 day

Custom solutions are easy to design and hard to implement, manage and ensure that they are bug-free. An Azure function together with a timer or trigger could do the trick. But it is not fully compliant, is not certified and requires effort and resources to manage and maintain.

All the previous requirements from the cyber-security team are supported by Azure Policy. We can define a policy that would Deny or Audit different rules/policies for each of them, helping us define the cloud governance across our organization.

What is the difference between Deny and Audit?

• Deny: But defining a deny policy, the creation of a specific item is blocked. For example, creating a key in Azure Key Vault that is under the minimum key size.
• Audit: This allows creating items that do not comply with the policy and trigger an alert that can notify another system or group of people.

The full list of Azure Policies that we can define for Azure Key Vault is available here. For Azure Resources, the cost of using Azure Policy is none. There is no additional cost of defining Azure Policies for Azure Key Vault or for any other resource.

Remember that there is no latency when you create an Azure Policy. Nevertheless, when you delete an Azure Policy, it can take up to 24 hours to stop being enforced. A workaround for this is to update the ‘effect’ assignment to ‘Disabled’.