[Cryptography] practical verifiable systems -- forensic and otherwise, cheap and otherwise

[Peter Gutmann]

Steve Weis <steveweis at gmail.com> writes:

>When it comes to measured boots with Trusted Execution (TXT), the lack of
>visibility into the BIOS is a big gap because of SMM. You can detect when the
>BIOS has changed, but don't know that the SMM loaded by BIOS is actually good.

If SMM, ring -1 access to your system, is bad, LOM, ring -2 access, is a
nightmare, typically an ancient, buggy, vuln-riddled version of Linux running
a collection of equally buggy and insecure services that have complete
backdoor control over your system and that typically can't actually be
disabled even if you think you've disabled them.

I don't remember offhand seeing much about exploiting the various LOM systems
in the NSA's catalogues, but I'd be very surprised if they didn't have
implants for the various systems out there.

Peter.