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9.3.5 Ensure 'Allow trusted Microsoft services to access this resource' is Enabled for Storage Account Access

Information

NOTE: This recommendation assumes that the Public network access parameter is set to Enabled from selected virtual networks and IP addresses . Please ensure the prerequisite recommendation has been implemented before proceeding:

 - Ensure Default Network Access Rule for Storage Accounts is Set to Deny

If the Allow trusted Microsoft services to access this resource exception is enabled, the following services are granted access to the storage account:

 - Azure Backup,
 - Azure Data Box,
 - Azure DevTest Labs,
 - Azure Event Grid,
 - Azure Event Hubs,
 - Azure File Sync,
 - Azure HDInsight,
 - Azure Import/Export,
 - Azure Monitor,
 - Azure Networking Services, and
 - Azure Site Recovery (when registered in the subscription).

NOTE: If none of the services listed in the Description are in use in your environment, you may wish to make an exception to this recommendation and disable 'Allow trusted Microsoft services to access this resource.'

Turning on firewall rules for a storage account will block access to incoming requests for data, including from other Azure services.

Some Azure services that interact with storage accounts operate from networks that can't be granted access through network rules. To help this type of service work as intended, allow the set of trusted Azure services to bypass the network rules. These services will then use strong authentication to access the storage account.

Solution

Remediate from Azure Portal

 - Go to Storage Accounts.
 - For each storage account, under Security + networking, click Networking.
 - Under the Public access tab, look for the Resource settings: Virtual networks, IP Addresses, and exceptions heading, then click the View button.
 - In the Resource Access settings pane, go to the Exceptions header and check the box next to Allow trusted Microsoft services to access this resource.
 - Click Save.

Remediate from Azure CLI

Use the below command to update bypass to Azure services.

az storage account update --name <StorageAccountName> --resource-group <resourceGroupName> --bypass AzureServices

Impact:

This creates authentication credentials for services that need access to storage resources so that services will no longer need to communicate via network request. There may be a temporary loss of communication as you set each Storage Account. It is recommended to not do this on mission-critical resources during business hours.

See Also

https://workbench.cisecurity.org/benchmarks/24282

Item Details

Category: ACCESS CONTROL, MEDIA PROTECTION, SYSTEM AND COMMUNICATIONS PROTECTION, SYSTEM AND INFORMATION INTEGRITY

References: 800-53|AC-3, 800-53|AC-5, 800-53|AC-6, 800-53|AC-17, 800-53|AC-17(1), 800-53|MP-2, 800-53|SC-7, 800-53|SI-4, CSCv7|13.3

Plugin: microsoft_azure

Control ID: 01e00fcd6a6527f16b3d5552919f870e6ef88d8bb1be7e5885f6f03a355fcd1b