UEFI Secure Boot is a security standard that helps ensure that your PC boots using only software that is trusted by the PC manufacturer. For certain virtual machine hardware versions and operating systems, you can activate secure boot just as you can for a physical machine.

In an operating system that supports UEFI secure boot, each piece of boot software is signed, including the bootloader, the operating system kernel, and operating system drivers. The virtual machine's default configuration includes several code signing certificates.
  • A Microsoft certificate that is used only for booting Windows.
  • A Microsoft certificate that is used for third-party code that is signed by Microsoft, such as Linux bootloaders.
  • A VMware certificate that is used only for booting ESXi inside a virtual machine.

The virtual machine's default configuration includes one certificate for authenticating requests to modify the secure boot configuration, including the secure boot revocation list, from inside the virtual machine, which is a Microsoft KEK (Key Exchange Key) certificate.

VMware Tools version 10.1 or later is required for virtual machines that use UEFI secure boot. You can upgrade those virtual machines to a later version of VMware Tools when it becomes available.

For Linux virtual machines, VMware Host-Guest Filesystem is not supported in secure boot mode. Remove VMware Host-Guest Filesystem from VMware Tools before you activate secure boot.

Note: If you turn on secure boot for a virtual machine, you can load only signed drivers into that virtual machine.

This task describes how to use the vSphere Client to activate and deactivate secure boot for a virtual machine. You can also write scripts to manage virtual machine settings. For example, you can automate changing the firmware from BIOS to EFI for virtual machines with the following PowerCLI code: 

$vm = Get-VM TestVM

$spec = New-Object VMware.Vim.VirtualMachineConfigSpec
$spec.Firmware = [VMware.Vim.GuestOsDescriptorFirmwareType]::efi
$vm.ExtensionData.ReconfigVM($spec)
See VMware PowerCLI User's Guide for more information.

Prerequisites

You can activate secure boot only if all prerequisites are met. If prerequisites are not met, the check box is not visible in the vSphere Client.
  • Verify that the virtual machine operating system and firmware support UEFI boot.
    • EFI firmware
    • Virtual hardware version 13 or later.
    • Operating system that supports UEFI secure boot.
    Note: Some guest operating systems do not support changing from BIOS boot to UEFI boot without guest OS modifications. Consult your guest OS documentation before changing to UEFI boot. If you upgrade a virtual machine that already uses UEFI boot to an operating system that supports UEFI secure boot, you can activate Secure Boot for that virtual machine.
  • Turn off the virtual machine. If the virtual machine is running, the check box is dimmed.

Procedure

  1. Browse to the virtual machine in the vSphere Client inventory.
  2. Right-click the virtual machine and select Edit Settings.
  3. Click the VM Options tab, and expand Boot Options.
  4. Under Boot Options, ensure that firmware is set to EFI.
  5. Select your task.
    • Select the Secure Boot check box to activate secure boot.
    • Deselect the Secure Boot check box to deactivate secure boot.
  6. Click OK.

Results

When the virtual machine boots, only components with valid signatures are allowed. The boot process stops with an error if it encounters a component with a missing or invalid signature.