I'm trying to patch my bootmgfw.efi
file to change the background color of the BitLocker password prompt and other Windows bootup screens. I found the values to search for and replace for the color (B2 67 20 FF
) and verified in IDA Pro that they were all near calls to functions related to the display (they were.) I copied the file to my EFI system partition, backing up the original, and rebooted.
When my computer rebooted, after the BIOS finished, it took me to a screen, in my new color, with the following error:
Recovery
Your PC needs to be repaired.
The digital signature for this file couldn't be verified.
Error code: 0xc0000428
You'll need to use the recovery tools on your installation media. If you don't have any
installation media (like a disc or USB device), contact your system administrator or PC
manufacturer.Press Esc for UEFI Firmware Settings
Pressing Escape didn't take me to a menu where I could disable the signature checking or anything; just my CMOS setup, where I already have Secure Boot disabled.
I was able to easily restore the backup using the installation media as it said, but how can I tell Windows that the invalid digital signature is not the result of malicious software, but rather an intentional change on my part?