You should repost your more detailed questions to one of the dedicated Secure Boot threads, instead of continuing here ("Windows on incompatible HW").
Did you manually update your Secure Boot Keys ?
But I will try to provide some quick answers.
Typically NVRAM settings for BIOS are treated separately from the UEFI variables. Whether a firmware update erases all existing NVRAM settings is up to how the OEM handles it. There are reported instances where a BIOS flash resets all the BIOS settings, but that's not an universal for all BIOS'es.
You seem to worried about the OS level, which some security products claim they can partially protect from rootkits (or at least if you boot into offline mode, and scan it from outside the normal Windows instance). None of that will matter to an UEFI rootkit.
Some vendors like HP have Sure Start, and other 3rd-parties sell custom UEFI extensions which function as security checks on added UEFI code. They run at the UEFI level. As a normal retail user, you won't have any of those to protect you unless your PC is an enterprise-grade model.
For older machines, you may have two options depending on what your OEM provided you in BIOS:
- Manual enrollment of KEK CA 2023 thru the BIOS menu
- Clearing all onboard certs, and allowing a script or tool to install a substitute PK and KEK, so that the rest of CA 2023 certs can be installed.
I can't tell you if those two options are available to you. You will have to examine your BIOS menus, and see what the vendor provided.
Did you manually update your Secure Boot Keys ?
But I will try to provide some quick answers.
There is legitimate concern about the limited NVRAM size on some older BIOS'es. But it's not about boot entries, it's because the old UEFI spec only recommended allocating a fixed amount of NVRAM for all UEFI cert entries. Steadily adding signature hashes to the DBX list (over time) may eventually exhaust the limited space which certs are allowed to fit under.Some confusion still, in the case that a PC can not update to the CA 2023 because there is not enough room or what ever. -- If I add a boot entry as a check to see if it will be overwritten after a BIOS flash as some BIOS does not wipe out the NVRAM during a flash if a PC has been re-flashed with the latest BIOS and it removed the boot entry I made, this would clean up any firmware modification that could exist. ? Because if the reflash of the bios removes the boot entry it will also remove everything from the NVRAM. ?
Typically NVRAM settings for BIOS are treated separately from the UEFI variables. Whether a firmware update erases all existing NVRAM settings is up to how the OEM handles it. There are reported instances where a BIOS flash resets all the BIOS settings, but that's not an universal for all BIOS'es.
Rootkits can exist at multiple levels. On the system disk, buried in the kernel files or loaded at boot time. On the UEFI, as one of the UEFI routines that's executed during power up & boot. UEFI has other functions like talking to your graphics chip (or card), so it can display a working screen in BIOS.If the hard drive was cleaned with the manufactures CLEAN function - this wipes everything off the SSD drive --- and I did not add any drivers that were not on the windows 11 install unless they were checked to be safe, in this case this machine would be free of any firmware compromise. ? --
RIGHT? at least its 99.99% likely to be clean of any firmware modification. ?
Apparently the compromise happens when we allow a hardware driver that is not signed - it has the ability to infect the firmware. ? It seams if a Paid version of Antivirus was running on this machine then compromise of the firmware would be unlikely ? My understanding is firmware rootkit happens by installing unsigned programs that were not hash checked. IM still a bit confused as to how a firmware compromise happens without a person being present at the machine ? or even how the keys get updated to CA 2023 without me being present. I would at least like to find out if I can make a safe OFFLINE system out of these older machines that refuse to update to CA 2023
You seem to worried about the OS level, which some security products claim they can partially protect from rootkits (or at least if you boot into offline mode, and scan it from outside the normal Windows instance). None of that will matter to an UEFI rootkit.
Some vendors like HP have Sure Start, and other 3rd-parties sell custom UEFI extensions which function as security checks on added UEFI code. They run at the UEFI level. As a normal retail user, you won't have any of those to protect you unless your PC is an enterprise-grade model.
For older machines, you may have two options depending on what your OEM provided you in BIOS:
- Manual enrollment of KEK CA 2023 thru the BIOS menu
- Clearing all onboard certs, and allowing a script or tool to install a substitute PK and KEK, so that the rest of CA 2023 certs can be installed.
I can't tell you if those two options are available to you. You will have to examine your BIOS menus, and see what the vendor provided.
My Computer
System One
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- OS
- Windows 7





