Re: https://firmwaresecurity.com/2017/05/25/intel-atr-releases-uefi-firmware-training-materials/ and https://firmwaresecurity.com/2019/11/22/intel-atr-training-no-longer-publicly-available/
A few years ago, Intel had a group called Advanced Threat Research (ATR), and they created some great training material for Intel BIOS/UEFI security. This training material was used in expensive multi-day pre-conference training by led by Intel and others.
A few Intel reorgs later, and with many of the people moved on (mostly to Eclypsium), and for reasons I am not sure, the training material was taken down, for reason(s) I am not aware of. There’s a comment in the above blog post where someone had a copy of the content, but that Google Drive URL is now 404.
Anyway, I notice there’s at least two current source of this training, if you have not studied this stuff before it is worth reading.
Don’t presume these files will be there in the future, cache a copy locally.