Assume that the file partition where the PC operating system and user data reside are sealed by a number of PCRs (Platform Configuration Registers) dedicated to BIOS measurements. What happens during the boot process if the BIOS is infected by a root kit?
Bootstrapping Trust with a TPM:
When the machine is powered on, the root of trust for measurement automatically measures the BIOS, and extends a PCR register inside the TPM with that measurement. Then, control is transferred to the BIOS. The BIOS next measures the boot loader before transferring control to it. This process continues with the loading of the OS kernel. The kernel then measures all code that is loads for execution before transferring control to it.
This means, the first attestation of BIOS (computed hash is not the same as before, because the BIOS is infected by a root kit) will fail. Therefore the control is not transferred to the boot loader and the operating system will not start?