BIOS and Secure Boot State Detection during a Task Sequence Part 2

In BIOS and Secure Boot State Detection Part 1, I talked about the various states a system can be in for the BIOS Mode and Secure Boot state. Having these states defined as OSD variables can be useful in determining what actions need to be performed in order to switch a system to UEFI Native with Secure Boot enabled. Depending on how you perform the vendor firmware changes, you may or may not need to define the difference between UEFI Hybrid and UEFI Native. UEFI Hybrid is when the system is running UEFI and the Compatibility Support Module (CSM) is enabled (this is how you can run Windows 7 in UEFI mode – yes, really). In order to enable Secure Boot, the CSM needs to be disabled first. Also, for Secure Boot state, you may or may not need to define all of the possible options. If the goal is to get to Secure Boot enabled, that may be good enough to just test for that. However, Secure Boot disabled may be a nice to have in the case you have systems that do not play well with Secure Boot being enabled.

I start off by creating a group called Set BIOS and Secure Boot Variables. For a Windows 10 In-place Upgrade Task Sequence, I place this group after the Install Updates step in the Post-Processing group (but more on that in another post). This way, the system is already running Windows 10, which is a Secure Boot capable operating system (unlike Windows 7, which is not capable of running Secure Boot). The first Task Sequence variable I like to define is called BIOSMode, I set this to LegacyBIOS on the condition that _SMSTSBootUEFI equals FALSE.

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We could just use the _SMSTSBootUEFI variable, however it is not as intuitive to other administrators if they need to read or edit the Task Sequence or read Status Messages and/or log files.

Next, add another Task Sequence variable called SecureBootState with the value Enabled. The condition on this is going to be based on the registry value:  HKLM\SYSTEM\CurrentControlSet\Control\SecureBoot\State\UEFISecureBootEnabled = 1.

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Now add another Set Task Sequence variable step with the same name, SecureBootState, but this time set the value to Disabled. The condition on this is going to be based on the registry value:  HKLM\SYSTEM\CurrentControlSet\Control\SecureBoot\State\UEFISecureBootEnabled = 0.

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There is also the Secure Boot state of unknown or NA, but for the time being I do not use this one in any of my Task Sequences. I also do not use the condition where SecureBootState = Disabled currently, but I figured it would be handy to have it in the future if needed. I have also created an item on uservoice so that maybe one day we will see a variable like this as part of the product: Create an OSD variable for Secure Boot – _SMSTSSecureBootState.

Feel free to download my exported Set BIOS and Secure Boot Variables Task Sequence here (created on Configuration Manager Current Branch 1702). Stay tuned on how to use these variables in a BIOS to UEFI Task Sequence…

Originally posted on https://miketerrill.net/

One thought on “BIOS and Secure Boot State Detection during a Task Sequence Part 2

  1. Pingback: Mike on Windows Config Mgr and Secure Boot | Firmware Security

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