4.11 Ensure Storage for Critical Data are Encrypted with Customer Managed Keys (CMK)

Information

Enable sensitive data encryption at rest using Customer Managed Keys (CMK) rather than Microsoft Managed keys.

Rationale:

By default, data in the storage account is encrypted using Microsoft Managed Keys at rest. All Azure Storage resources are encrypted, including blobs, disks, files, queues, and tables. All object metadata is also encrypted. If you want to control and manage this encryption key yourself, however, you can specify a customer-managed key. That key is used to protect and control access to the key that encrypts your data. You can also choose to automatically update the key version used for Azure Storage encryption whenever a new version is available in the associated Key Vault.

While it is possible to automate the assessment of this recommendation, the assessment status for this recommendation remains 'Manual.' This is because the recommendation pertains to storage accounts that store critical data and is therefore not applicable to all storage accounts.

Impact:

If the key expires by setting the 'activation date' and 'expiration date', the user must rotate the key manually.

Using Customer Managed Keys may also incur additional man-hour requirements to create, store, manage, and protect the keys as needed.

Solution

Remediate from Azure Portal

Go to Storage Accounts

For each storage account, under Security + networking, go to Encryption

Set Encryption type to Customer-managed keys

Select an encryption key or enter a key URI

Click Save

Default Value:

By default, Encryption type is set to Microsoft Managed Keys.

See Also

https://workbench.cisecurity.org/benchmarks/16820

Item Details

Category: IDENTIFICATION AND AUTHENTICATION, SYSTEM AND COMMUNICATIONS PROTECTION

References: 800-53|IA-5(1), 800-53|SC-28, 800-53|SC-28(1), CSCv7|14.8

Plugin: microsoft_azure

Control ID: ad5ccdebb42295e8e73fd41819c4ff38a573f207c1f2434154f22e8c8abb0eb5