Detections
Analytics
8.5 Ensure that 'Disk Network Access' is NOT set to 'Enable public access from all networks'
Information
Virtual Machine Disks and snapshots can be configured to allow access from different network resources.Rationale:
The setting 'Enable public access from all networks' is, in many cases, an overly permissive setting on Virtual Machine Disks that presents atypical attack, data infiltration, and data exfiltration vectors. If a disk to network connection is required, the preferred setting is to 'Disable public access and enable private access.'
Impact:
The setting 'Disable public access and enable private access' will require configuring a private link (URL in references below).
The setting 'Disable public and private access' is most secure and preferred where disk network access is not needed.
Solution
Remediate from Azure PortalPart A. Select the Virtual Machine to Remediate
Using the search bar, search for and open the Virtual Machines service.
Click on the name of the Virtual Machine to be remediated.
Part B. Remediate each Virtual Machine Disk individually
From the selected Virtual Machine resource window, expand the Settings menu item and click Disks.
For each disk, click the name of the disk to open the disk resource window.
From the selected Disk resource window, expand the Settings menu item, and click Networking.
Under Network access, select the radio button for either:
Disable public access and enable private access
Disable public and private access
Repeat Part B for each Disk attached to a VM.
Repeat Parts A and B to remediate all Disks in all VMs.
Remediate from PowerShell
To disable PublicNetworkAccess and to set a DenyAll setting for the disk's NetworkAccessPolicy for each managed disk, run the following command:
$disk = Get-AzDisk -ResourceGroupName '<resource group name>' -DiskName '<disk name>'
$disk.NetworkAccessPolicy = 'DenyAll'
$disk.PublicNetworkAccess = 'Disabled'
Update-AzDisk -ResourceGroup '<resource group name> -DiskName $disk.Name -Disk $disk
To disable PublicNetworkAccess and to set an AllowPrivate setting for the disk's NetworkAccessPolicy for each managed disk, run the following command:
$disk = Get-AzDisk -ResourceGroupName '<resource group name>' -DiskName '<disk name>'
$disk.NetworkAccessPolicy = 'AllowPrivate'
$disk.PublicNetworkAccess = 'Disabled'
$disk.DiskAccessId = '/subscriptions/<subscription ID>/resourceGroups/<resource group name>/providers/Microsoft.Compute/diskAccesses/<private disk access name>
Update-AzDisk -ResourceGroup '<resource group name> -DiskName $disk.Name -Disk $disk
Remediate from Azure CLI
To configure a disk to allow private access only, run the following command making sure you have the Disk Access ID from a private disk access end point.
az disk update --name <managed disk name> --resource-group <resource group name> --network-access-policy AllowPrivate --disk-access <disk access ID>
To completely disable public and private access for a disk, run the following command (still in preview) for each disk:
az disk update --name <managed disk name> --resource-group <resource group name> --public-network-access Disabled --network-access-policy DenyAll
Default Value:
By default, Disk Network access is set to Enable public access from all networks.
See Also
Item Details
Audit Name: CIS Microsoft Azure Foundations v3.0.0 L1
Category: CONFIGURATION MANAGEMENT, MAINTENANCE
References: 800-53|CM-7, 800-53|MA-4, CSCv7|5.1
Plugin: microsoft_azure
Control ID: 4c116736fd43fc4d2e3603f36b783f1b5a59ffdb5d89261425fc2bb1e33a9f4f