Microsoft AzureOverview
Enable sensitive data encryption at rest using Customer Managed Keys rather than Microsoft Managed Keys.
Rationale
By default, data at rest in the storage account is encrypted using Microsoft Managed Keys. All Azure Storage resources are encrypted, including blobs, disks, files, queues, and tables. All object metadata is also encrypted. However, if you want to control and manage this encryption key, specify a customer-managed key. That key is used to protect and control access to the key that encrypts your data. You can also automatically update the key version used for Azure Storage encryption whenever a new version is available in the associated Key Vault.
Impact
If the key expires after 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.
Default Value
By default, Encryption type is set to Microsoft-managed keys
References
- https://learn.microsoft.com/en-us/azure/storage/common/storage-service-encryption
- https://learn.microsoft.com/en-us/azure/security/fundamentals/data-encryption-best-practices#protect-data-at-rest
- https://learn.microsoft.com/en-us/azure/storage/common/storage-service-encryption#azure-storage-encryption-versus-disk-encryption
- https://learn.microsoft.com/en-us/security/benchmark/azure/security-controls-v3-data-protection#dp-5-use-customer-managed-key-option-in-data-at-rest-encryption-when-required
Remediation guidance
Azure Console
- Go to
Storage Accounts. - For each storage account, go to
Encryption. - Set Customer Managed Keys.
- Select the Encryption key and enter the appropriate setting value.
- Click
Save.
Service-wide remediation
Recommended when many resources are affected: fix the platform baseline first so new resources inherit the secure setting, then remediate the existing flagged resources in batches.
Azure
Use management group or subscription Azure Policy assignments, remediation tasks where supported, landing-zone standards, and IaC modules so drift is prevented at scale.
Operational rollout
- Fix the baseline first at the account, subscription, project, cluster, or tenant scope that owns this control.
- Remediate the currently affected resources in batches, starting with internet-exposed and production assets.
- Re-scan and track approved exceptions with an owner and expiry date.
Query logic
These are the stored checks tied to this control.
Storage for critical data is encrypted with Customer Managed Key
Connectors
Covered asset types
Expected check: eq []
{storageAccounts(where:{byokEncrypted_NOT:true}){...AssetFragment}}
