7.2 Ensure Virtual Machines are utilizing Managed Disks

Information

Migrate blob-based VHDs to Managed Disks on Virtual Machines to exploit the default features of this configuration. The features include:

Default Disk Encryption

Resilience, as Microsoft will managed the disk storage and move around if underlying hardware goes faulty

Reduction of costs over storage accounts

Rationale:

Managed disks are by default encrypted on the underlying hardware, so no additional encryption is required for basic protection. It is available if additional encryption is required. Managed disks are by design more resilient that storage accounts.

For ARM-deployed Virtual Machines, Azure Adviser will at some point recommend moving VHDs to managed disks both from a security and cost management perspective.

Impact:

There are additional costs for managed disks based off of disk space allocated. When converting to managed disks, VMs will be powered off and back on.

Solution

From Azure Portal

Using the search feature, go to Virtual Machines

Select the virtual machine you would like to convert

Select Disks in the menu for the VM

At the top select Migrate to managed disks

You may follow the prompts to convert the disk and finish by selecting Migrate to start the process

NOTE VMs will be stopped and restarted after migration is complete.
From PowerShell

Stop-AzVM -ResourceGroupName $rgName -Name $vmName -Force
ConvertTo-AzVMManagedDisk -ResourceGroupName $rgName -VMName $vmName
Start-AzVM -ResourceGroupName $rgName -Name $vmName

Default Value:

Managed disks or are an option upon the creation of VMs.

See Also

https://workbench.cisecurity.org/benchmarks/12346

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: 8863a3adfdac7520ad1bd62dd77891ef50a69eb5552ec027811d6227fe482372