Skip to main content

lacework-global-573

7.1 Ensure Virtual Machines are utilizing Managed Disks (Automated)​

note

This rule has been changed to automated, see Automated Rules for CIS Azure 1.5.0 for details.

Profile Applicability​

• Level 1

Description​

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

1) Default Disk Encryption
2) Resilience, as Microsoft will managed the disk storage and move around if underlying hardware goes faulty
3) 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.

Audit​

From Azure Console​

  1. Using the search feature, go to Virtual Machines
  2. Click the Manage view dropdown, then select Edit columns
  3. Add Uses managed disks to the selected columns
  4. Select Save
  5. Ensure all virtual machines listed are using managed disks

Using Azure Powershell​

Get-AzVM | ForEach-Object {"Name: " + $_.Name;"ManagedDisk Id: " + $_.StorageProfile.OsDisk.ManagedDisk.Id;""}

Example output:

Name: vm1
ManagedDisk Id: /disk1/id

Name: vm2
ManagedDisk Id: /disk2/id

If the 'ManagedDisk Id' field is empty the os disk for that vm is not managed.

Remediation​

From Azure Console​

  1. Using the search feature, go to Virtual Machines
  2. Select the virtual machine you would like to convert
  3. Select Disks in the menu for the VM
  4. At the top select Migrate to managed disks
  5. 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.

Using Azure Powershell​

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

References​

https://docs.microsoft.com/en-us/azure/virtual-machines/windows/convert-unmanaged-to-managed-disks
https://docs.microsoft.com/en-us/security/benchmark/azure/security-controls-v3-data-protection#dp-4-enable-data-at-rest-encryption-by-default
https://docs.microsoft.com/en-us/azure/virtual-machines/faq-for-disks
https://azure.microsoft.com/en-us/pricing/details/managed-disks/