The Memory Sinkhole - Unleashing An X86 Design Flaw Allowing Universal Privilege Escalation

Christopher Domas demonstrates a critical x86 design flaw that allows code execution to break out of ring 0 into the highly privileged System Management Mode.

by Christopher Domas In x86, beyond ring 0 lie the more privileged realms of execution, where our code is invisible to AV, we have unfettered access to hardware, and can trivially preempt and modify the OS. The architecture has heaped layers upon layers of protections on these negative rings, but 40 years of x86 evolution have left a labyrinth of forgotten backdoors into the ultra-privileged modes. Lost in this byzantine maze of decades-old architecture improvements and patches, there lies a design flaw that's gone unnoticed for 20 years. In one of the most bizarre and complex vulnerabilities we've ever seen, we'll release proof-of-concept code exploiting the vast, unexplored wasteland of forgotten x86 features, to demonstrate how to jump malicious code from the paltry ring 0 into the deepest, darkest realms of the processor. Best of all, we'll do it with an architectural 0-day built into the silicon itself, directed against a uniquely vulnerable string of code running on every single system.