Cis Azure Foundations 9.2.3

Ensure 'Versioning' is set to 'Enabled' on Azure Blob Storage storage accounts

Description

Enabling blob versioning allows for the automatic retention of previous versions of objects. With blob versioning enabled, earlier versions of a blob are accessible for data recovery in the event of modifications or deletions.

Rationale

Blob versioning safeguards data integrity and enables recovery by retaining previous versions of stored objects, facilitating quick restoration from accidental deletion, modification, or malicious activity.

Impact

Enabling blob versioning for a storage account creates a new version with each write operation to a blob, which can increase storage costs. To control these costs, a lifecycle management policy can be applied to automatically delete older versions.

Audit Procedure

Audit from Azure Portal

1. Go to Storage accounts.
2. Click the name of a storage account with blob storage.
3. In the Overview page, on the Properties tab, under Blob service, ensure Versioning is set to Enabled.
4. Repeat steps 1-3 for each storage account with blob storage.

Audit from Azure CLI

Run the following command to list storage accounts:

az storage account list

Run the following command to determine if a storage account has containers:

az storage container list --account-name <storage-account>

For each storage account with containers, ensure that the output of the below command contains "isVersioningEnabled": true:

az storage account blob-service-properties show --account-name <storage-account>

Audit from PowerShell

Run the following command to list storage accounts:

Get-AzStorageAccount

Run the following command to create an Azure Storage context for a storage account:

$context = New-AzStorageContext -StorageAccountName <storage-account>

Run the following command to list containers for the storage account:

Get-AzStorageContainer -Context $context

If the storage account has containers, run the following command to get the blob service properties of the storage account:

$account = Get-AzStorageBlobServiceProperty -ResourceGroupName <resource-group> -StorageAccountName <storage-account>

Run the following command to get the blob versioning setting for the storage account:

$account.IsVersioningEnabled

Ensure that the command returns True.

Expected Result

isVersioningEnabled should be true for all storage accounts with blob storage.

Remediation

Remediate from Azure Portal

1. Go to Storage accounts.
2. Click the name of a storage account with blob storage.
3. In the Overview page, on the Properties tab, under Blob service, click Disabled next to Versioning.
4. Under Tracking, check the box next to Enable versioning for blobs.
5. Select the radio button next to Keep all versions or Delete versions after (in days).
6. If selecting to delete versions, enter a number of in the box after which to delete blob versions.
7. Click Save.
8. Repeat steps 1-7 for each storage account with blob storage.

Remediate from Azure CLI

For each storage account requiring remediation, run the following command to enable blob versioning:

az storage account blob-service-properties update --account-name <storage-account> --enable-versioning true

Remediate from PowerShell

For each storage account requiring remediation, run the following command to enable blob versioning:

Update-AzStorageBlobServiceProperty -ResourceGroupName <resource-group> -StorageAccountName <storage-account> -IsVersioningEnabled $true

Default Value

Blob versioning is disabled by default on storage accounts.

References

1. https://learn.microsoft.com/en-us/cli/azure/storage/account
2. https://learn.microsoft.com/en-us/cli/azure/storage/account/blob-service-properties
3. https://learn.microsoft.com/en-us/powershell/module/az.storage/get-azstorageaccount
4. https://learn.microsoft.com/en-us/powershell/module/az.storage/new-azstoragecontext
5. https://learn.microsoft.com/en-us/powershell/module/az.storage/get-azstoragecontainer
6. https://learn.microsoft.com/en-us/powershell/module/az.storage/get-azstorageblobserviceproperty
7. https://learn.microsoft.com/en-us/powershell/module/az.storage/update-azstorageblobserviceproperty
8. https://learn.microsoft.com/en-us/azure/storage/blobs/versioning-overview
9. https://learn.microsoft.com/en-us/azure/storage/blobs/lifecycle-management-overview

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