Introduction
In the world of cloud architecture, "default" is rarely enough. When a company's data is on the line, the difference between a functional app and a secure app lies in the details of the infrastructure.
I recently architected a storage solution for a new enterprise application, that moves beyond basic configurations. This implementation focuses on the "Zero Trust" model, leveraging Customer-Managed Keys (CMK), User-Assigned Managed Identities, and Immutable Storage policies to ensure that data isn't just stored but it's fortified.
This guide walks through the end-to-end process of how I hardened the cloud environment.
Scenario: The company is designing and developing a new app. Developers need to ensure the storage is only accessed using keys and managed identities. The developers would like to use role-based access control. To help with testing, protected immutable storage is needed.
Skilling tasks
I exhibited the following skills:
- Create the storage account and managed identity.
- Secure access to the storage account with a key vault and key.
- Configure the storage account to use the customer managed key in the key vault
- Configure an time-based retention policy and an encryption scope.
Create the storage account and managed identity
Provide a storage account for the web app.
Step 1: In the portal, search for and select Storage accounts.
Step 2: Select + Create.
Step 3: For Resource group select Create new. Give your resource group a name and select OK to save your changes.
Step 4: Provide a Storage account name. Ensure the name is unique and meets the naming requirements.
Step 5: Move to the Encryption tab.
Step 6: Check the box for Enable infrastructure encryption.
Notice the warning, This option cannot be changed after this storage account is created.
Step 7: Select Review + Create.
Wait for the resource to deploy.
Provide a managed identity for the web app to use.
Step 1: Search for and select Managed identities.
Step 2: Select Create.
Step 3: Select your resource group.
Step 4: Give your managed identity a name.
Step 5: Select Review and create, and then Create.
Assign the correct permissions to the managed identity. The identity only needs to read and list containers and blobs.
Step 1: Search for and select your storage account.
Step 2: Select the Access Control (IAM) blade.
Step 3: Select Add role assignment (center of the page).
Step 4: On the Job functions roles page, search for and select the Storage Blob Data Reader role.
Step 5: On the Members page, select Managed identity.
Step 6: Select Select members, in the Managed identity drop-down select User-assigned managed identity.
Step 7: Select the managed identity you created in the previous step.
Step 8: Click Select and then Review + assign the role.
Step 9: Select Review + assign a second time to add the role assignment.
Your storage account can now be accessed by a managed identity with the Storage Data Blob Reader permissions.
Secure access to the storage account with a key vault and key
To create the key vault and key needed here, your user account must have Key Vault Administrator permissions.
Step 1: In the portal, search for and select Resource groups.
Step 2: Select your resource group, and then the Access Control(IAM) blade.
Step 3: Select Add role assignment (center of the page).
Step 4: On the Job functions roles page, search for and select the Key Vault Administrator role.
Step 5: On the Members page, select User, group, or service principal.
Step 6: Select Select members.
Step 7: Search for and select your user account. Your user account is shown in the top right of the portal.
Step 8: Click Select and then Review + assign.
Step 9: Select Review + assign a second time to add the role assignment.
Create a key vault to store the access keys.
Step 1: In the portal, search for and select Key vaults.
Step 2: Select Create.
Step 3: Select your resource group.
Step 4: Provide the name for the key vault. The name must be unique.
Step 5: Ensure on the Access configuration tab that Azure role-based access control (recommended) is selected.
Step 6: Select Review + create.
Step 7: Wait for the validation checks to complete and then select Create.
Step 8: After the deployment, select Go to resource.
Step 9: On the Overview blade ensure both Soft-delete and Purge protection are enabled.
Create a customer-managed key in the key vault.
Step 1: In your key vault, in the Objects section, select the Keys blade.
Step 2: Select Generate/Import and Name the key.
Step 3: Take the defaults for the rest of the parameters, and Create the key.
Configure the storage account to use the customer managed key in the key vault
Before you can complete the next steps, you must assign the Key Vault Crypto Service Encryption User role to the managed identity.
Step 1: In the portal, search for and select Resource groups.
Step 2: Select your resource group, and then the Access Control (IAM) blade.
Step 3: Select Add role assignment (center of the page).
Step 4: On the Job functions roles page, search for and select the Key Vault Crypto Service Encryption User role.
Step 5: On the Members page, select Managed identity.
Step 6: Select Select members, in the Managed identity drop-down select User-assigned managed identity.
Step 7: Select your managed identity.
Step 8: Click Select and then Review + assign.
Step 9: Select Review + assign a second time to add the role assignment.
Configure the storage account to use the customer managed key in your key vault.
Step 1: Return to your the storage account.
Step 2: In the Security + networking section, select the Encryption blade.
Step 3: Select Customer-managed keys.
Step 4: Select a key vault and key. Select your key vault and key.
Step 5: Select to confirm your choices.
Step 6: Ensure the Identity type is User-assigned.
Step 7:Select an identity.
Step 8: Select your managed identity then select Add.
Step 9: Save your changes.
If you receive an error that your identity does not have the correct permissions, wait a minute and try again.
Configure an time-based retention policy and an encryption scope.
The developers require a storage container where files can’t be modified, even by the administrator.
Step 1: Navigate to your storage account.
Step 2: In the Data storage section, select the Containers blade.
Step 3: Create a container called hold. Take the defaults. Be sure to Create the container.
Step 4: Upload a file to the container.
Step 5: In the Settings section, select the Access policy blade.
Step 6: In the Immutable blob storage section, select + Add policy.
Step 7: For the Policy type, select time-based retention.
Step 8: Set the Retention period to 5 days.
Step 9: Be sure to Save your changes.
Step 10: Try to delete the file in the container.
Step 11: Verify you are notified failed to delete blobs due to policy.
The developers require an encryption scope that enables infrastructure encryption.
Step 1: Navigate back to your storage account.
Step 2: In the Security + networking blade, select Encryption.
Step 3: In the Encryption scopes tab, select Add.
Step 4: Give your encryption scope a name.
Step 5: The Encryption type is Microsoft-managed key.
Step 6: Set Infrastructure encryption to Enable.
Step 7: Create the encryption scope.
Step 8: Return to your storage account and create a new container.
_Notice on the New container page, there is the Name and Public access level.
Notice in the Advanced section you can select the Encryption scope you created and apply it to all blobs in the container_.
Cleanup your resources
If you are working with your own subscription and have completed these labs, take a minute to delete the lab resources. This will ensure resources are freed up and cost is minimized. The easiest way to delete the lab resources is to delete the lab resource group.
In the Azure portal, select the resource group, select Delete the resource group, Enter resource group name, and then click Delete.
Conclusion
Security is a Feature, not an Afterthought.
In modern cloud environments, "it works" is only half the requirement. The real challenge is ensuring it stays secure, compliant, and resilient. This implementation proves that by moving beyond default configurations—leveraging Customer-Managed Keys (CMK), User-Assigned Managed Identities, and Immutable Storage, we can build systems that protect data from both external threats and internal accidents.
For any organization, this architecture represents a shift toward a Zero Trust mindset. It demonstrates how to:
- Minimize Attack Surfaces: By eliminating shared secrets in favor of Managed Identities.
- Exert Total Control: Through granular RBAC and Key Vault governance.
- Guarantee Compliance: With time-based retention policies that satisfy even the strictest audit requirements.
Top comments (2)
Nicely written, welldone!
Thanks Sir!