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

Peter Gutmann pgut001 at cs.auckland.ac.nz
Wed Mar 4 23:00:17 EST 2015

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.


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