It appears Mac OS X 10.12.2 has some firmware-related security updates, with some defense against PCILeech:
macOS FileVault2 Password Retrieval
“macOS FileVault2 let attackers with physical access retrieve the password in clear text by plugging in a $300 Thunderbolt device into a locked or sleeping mac. The password may be used to unlock the mac to access everything on it. To secure your mac just update it with the December 2016 patches. Anyone including, but not limited to, your colleagues, the police, the evil maid and the thief will have full access to your data as long as they can gain physical access – unless the mac is completely shut down. If the mac is sleeping it is still vulnerable. Just stroll up to a locked mac, plug in the Thunderbolt device, force a reboot (ctrl+cmd+power) and wait for the password to be displayed in less than 30 seconds!
Recovering the password is just one of the things that are possible unless the security update is applied. Since EFI memory can be overwritten it is possible to do more evil …
December 13th: Apple released macOS 10.12.2 which contains the security update. At least for some hardware – like my MacBook Air.
Look at recent Tweets from Xeno Kovah, he has multiple posts with information about the 10.12.2 update:
I’ll admit, I didn’t find any firmwaer information in their release: