Rafal Sosnowski of Microsoft has a new blog post on TPM:
Hello everyone. It’s Rafal Sosnowski from Microsoft Dubai Security PFE Team. Today, I am going to talk about TPM Lockout state. TPM (Trusted Platform Module) is a small chip on the motherboard (discrete TPM) or part of the CPU implementation (firmware TPM) which can be used to securely store small amount of information (certificates, private keys, virtual smartcards, Bitlocker keys etc.). That data is completely isolated from HDD and partially from OS thus giving it maximum protection. To get access to that information from OS level user has to present some kind of authorization value. For example, Bitlocker PIN to get access to the Bitlocker Keys, Virtual smart-card PIN to get access to the certificates and private keys etc. However, TPM has special anti-hammering logic which prevents malicious user from guessing that authorization data indefinitely. Number of possible PIN failures varies across TPM specification: […]
Full post:
https://blogs.technet.microsoft.com/dubaisec/2016/07/10/tpm-lockout/
Firmware Security 