Researcher Names: Alex Tereshkin (twitter.com/AlexTereshkin), Alex Matrosov (twitter.com/matrosov), Adam ‘pi3’ Zabrocki (twitter.com/Adam_pi3)
Intel implemented a BIOS feature for server platforms that allowed users to silently run unsigned code stored locally in EFI vars (i.e. a backdoor-like functionality), effectively bypassing Secure Boot and TPM code measurements. This was enabled on production systems and it did not require physical access to run.
https://www.intel.com/content/www/us/en/security-center/advisory/intel-sa-00525.html