Is it possible to detect and remove rootkits such as Especter and Lojax when the sysrescuedisk and anti rootkit programs are unable to detect?

[Guest RegularPerson62]

Is there a way to detect and remove rootkits such as Especter and Lojax when the sysrescuedisk and anti rootkit programs are unable to detect? 

and when the bootloader doesn't allow boot from usb? 

[Marcos 4,551]

ESET detects even in UEFI if you install it. SysRescue doesn't scan UEFI.

[itman 1,497]

If you're referring to the Spectre rootkit, the POC is here: https://github.com/D4stiny/spectre .

I haven't found any documented cases where it has been deployed anywhere though.