God Mode unlocked: Hardware backdoors in x86 CPUs by Christopher Domas.
Domas has discovered a god mode in the VIA C3 Nehemiah chip (2003) by tracing a series of patents.
An impressive bit of work, but its greater importance lies in partially populating search terms to use when looking for similar patents.
Not to mention that confirmation of the existence of a god mode, not rumored, not whispered about, but a corroborated god mode, will encourage other security researchers to seek other god modes in other versions of chips.
There is a non-technical treatment of Domas’ discovery at: Hacker Finds Hidden ‘God Mode’ on Old x86 CPUs by Paul Wagenseil.
It’s a good summary article but be forewarned of Wagenseil’s take on security:
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The good news is that, as far as Domas knows, this backdoor exists only on VIA C3 Nehemiah chips made in 2003 and used in embedded systems and thin clients. The bad news is that it’s entirely possible that such hidden backdoors exist on many other chipsets.
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Wagenseil has that backwards. Good news would be god modes on all chipsets. Bad news would be god mode is a one-off mistake on the VIA C3 Nehemiah chip (2003). God modes make information security more sporting.
What chip set patents are you going to be researching this week?
Update, 14 August 2018: See the Rosenbridge project at Github for code, etc.