x86-64 Intel Firmware Attack and Defense


Xeno Kovah

x86-64 Intel Firmware Attacks and Defense - Class Trailer


This class is designed to give you all the background you need to understand how x86-64 firmware (aka UEFI BIOS) works, and what the most common security misconfigurations are. It will prepare you to be able to read and understand the existing attack and defense research in the space, taking an explicit walk through of the attack and defense moves and counter-moves threat tree. And as always, this classes teaches you to be comfortable with Reading The Fun Manual (RTFM!) to go seek out the most accurate details of how things work, and to see out new problems in new areas that no one's read yet with a security mindset.

Prerequisite Knowledge

Complexity: Advanced

You should have equivalent knowledge of x86-64 assembly, architecture, and specifically WinDbg as that provided in the x86-64 Assembly class, also offered at Ringzer0. You should also have the knowledge of control registers, model-specific registers, segmentation, and port IO provided in the x86-64 OS Internals class, also offered at Ringzer0. If you don't have that background, or if you just need a refresher, you can sign up for the x86-64 All You Can Learn Buffet class to go through that material before proceeding to this class's material. And then you can even further proceed to the bundled x86-64 Intel Firmware Attack & Defense class, if you complete all the material from this class.

Key Learning Objectives

  • Understand the original 16-bit “Real Mode” which the x86 CPU reset vector executes in.
  • Understand 16-bit segmentation & assembly.
  • Understand the evolution of Intel chipsets, and how to find the manual which corresponds to any given hardware.
  • Understand how firmware uses IO to configure Intel and 3rd party hardware at boot time.
  • Understand how firmware interacts with PCIe devices at boot time, both within the CPU/chipset, and 3rd party peripherals.
  • Understand the core purposes of PCIe Option ROMs, but also how they can be used by attackers.
  • Being capable of manually reading/writing the firmware-storage SPI flash through the register interface.
  • Understand the protection mechanisms for the SPI flash and how they can be bypassed.
  • Understand the protection mechanisms for System Management Mode how they can be bypassed.
  • Understand how Chipsec can be used to assess the security posture of a firmware for both attack and defense.
  • Understand how the ACPI S3 “sleep” power state can be used to attack systems.
  • Being comfortable with Reading The Fun Manual(!) to go seek out the most accurate details of how things work.

One-of-a-kind Class Format!

This class is run a little different from most classes. We provide you purpose-built recorded lectures instead of trapping you in realtime with live-lectures. But fear not, the instructor is always right there eagerly waiting to mingle with the students and answer any questions you have. (The instructor really likes being asked questions. It shows you're paying attention ;)). One of many benefits is that you can watch lectures at 2x speed and zoom ahead of the other students and get to the hands on labs quicker. Or if there's bits of material you already know, you can just skip them and move on to the bits you don't know! Another big benefit is that you get to take the full lectures and labs with you! That means if you forget stuff and then need it in 6 months, you can quickly re-bootstrap yourself! Or you can watch the class twice, to really grow those neural connections and cement it in your brain! And unlike live lectures, our lectures are always getting more factually accurate, by having any accidental errors edited out.

Because we give you all the lecture and lab materials and videos after class, what you're really paying for is support from the instructor! So you'll be entitled to keep asking up to 20 questions after class, with 1-2 hour turnaround answers (after accounting for time-zone differences.) This lets you keep productively working through the material if you run out of time at the conference. If you'd like to learn more about the benefits of this style of class delivery, please read this blog post.

Course Agenda

  • Introduction
    • Attacker motivations & capabilities
  • Reset Vector
    • The “Real Mode” execution environment
    • Reading reset vector assembly and the transitions to “Protected Mode”
  • Chipsets
    • The evolution of the platform architecture
    • Finding the correct manual for the hardware you bring to class, to find the correct offsets to memory mapped IO registers for the rest of the class
  • Input/Output
    • Memory Mapped IO (MMIO) as used by firmware
    • Port IO (PIO) as used by firmware
    • Hardware-defined vs. reconfigurable memory spaces
  • PCIe
    • Evolution, topology, and usage by firmware
    • Configuration address space MMIO vs. PIO accesses
    • Base address registers & extended configuration address space
    • “Option ROMs” and how they've been repeatedly used for attacks
  • SPI Flash
    • Introduction & supported SPI operation modes on x86
    • MMIO register-based SPI flash programming interface
    • SPI flash layout & the Intel flash descriptor
    • SPI protection threat tree, moves and counter-moves
      • Protected Range Registers (PRRs) and bypasses like failure to FLOCKDN + sleep attacks
      • SMM-based BIOS Lockdown and bypasses like SMI Suppression + sleep attacks
  • System Management Mode (SMM)
    • Introduction & System Management Interrupts (SMIs)
    • System Management RAM (SMRAM) & the protection thereof
    • SMM threat tree, moves and counter-moves:
      • Caching Attacks
      • Remapping Attacks
      • SMM Call-Out Vulnerabilities
      • SMM Confused Deputy Attacks
      • SMM TOCTOU Attacks
  • Power-transition attacks
    • x86 ACPI S3 low-power sleep effects on SPI & SMM protection
    • Attacks exploiting S3 sleep states
  • Conclusion

Hardware Requirements

  • PC (or x86 Mac) running Windows or Linux in a dedicated partition
  • Headphones for watching videos, (preferably over-ear so you're not disturbed as the instructor is walking around the class answering individuals' questions).

Software Requirements

  • Administrator privileges to install virtualization software on your machine.
  • Windows or Linux as the primary host
  • A link to a software setup guide will be sent before class, and the student should install before class to maximize time available for interaction with the instructor.

Other software includes Intel Simics, Chipsec, UEFITool, and Read-Write Everything.