x86-64 OS Internals



2 days

Delivery Method

Guided Own Pace



Seats Available



2 days

Delivery Method

Guided Own Pace




DATE: 21-22 August 2023

TIME: 09:00 to 17:00 ICT/GMT+7

Date Day Time Duration
21 Aug Monday 0900-17:00 ICT/GMT+7 8 Hours
22 Aug Tuesday 0900-17:00 ICT/GMT+7 8 Hours

Go HERE to take this class as a 4-Day Buffet course.
Go HERE to take this class as a 3-Day Buffet course.
Go HERE to join just the x86-64 assembly class.
Go HERE to join just the x86-64 Intel Firmware Attack & Defense class.

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


Key Learning Objectives
  • Understand how ring 0 (kernel) / ring 3 (userspace) privilege separation *really* works.
  • Understanding how to use CPUID to query the features available on your system, and how to read the Model Specific Registers (MSRs) to check which ones your OS has actually enabled.
  • Understand segmentation (and how it relates to privilege separation).
  • Understand interrupts (and how they pertain to system calls and debugging).
  • Understand system calls (and how they constitute a major attack surface of an OS).
  • Understand virtual memory and page table setup (and how it interacts with security mechanisms like XD, SMAP, and SMEP).
  • Understand how software and hardware breakpoints work.
  • Understand how port IO allows communication to legacy peripherals and VMWare’s control channel.
  • Being comfortable with Reading The Fun Manual (RTFM!) to go seek out the most accurate details of how things work.


What Students say about this training

I really liked that figure 2-2 being literally covered during the class. I was not expecting all of those concepts becoming familiar after the class. I felt really fulfilled after each section that we completed.”

“I enjoyed the class very much, especially the easy-going approach of Xeno presenting the material, whereby he does not make you feel overwhelmed about the material, but on the contrary he makes the content more approachable and within grasp to anyone who would like to learn very low level concepts. I also liked a lot that he also structure the course in such a way, that it really flows from the one topic to the next, which happens naturally, and also provides a top-bottom overview of the concepts taught, also facilitating getting a good grasp of the concepts.”

“The class was excellent, really high quality. What I want to see in the future is more of this high quality content.”

“I like the way videos are made for the classes. I like because there are interesting correlations made for some topics of the classes with some funny stuffs from real life, and Sonic of course, that make the learning process much easier. “

“The class is very well structured and fits very well someone looking to acquire the basics and expand its foundations.”

“The course was precise, engaging and the delivery was delightful. Xeno knows his content, the audience and the relevance to modern technology is clearly visible in the course. By the end of the course you will be more knowledgeable, confident and a little brain hurt. Can’t wait for the subsequent courses.”

“I watched some of the classes in 1.5x in general. But I think the normal pace of the videos were also quite good. I found the tiny references to popular games and movies during the lecture quite useful for maintaining attention to the material.”

“I enjoyed having the transcripts.”


Topics Covered



  • CPU Feature Identification instruction


Processor Execution Modes

  • Real mode, protected mode, IA-32e mode, system management mode


Model Specific Registers (MSRs)

  • Reading and writing MSRs (rdmsr, wrmsr)


Privilege Rings & Segmentation

  • Privilege rings start
  • Segment selectors & segment registers
  • Global Descriptor Table (GDT) & Local Descriptor Table (LDT)
  • Segment descriptors
  • Privilege rings finish
  • Call gates
  • Return to RTFM
  • Implicit and explicit use of segmentation



  • Interrupts vs. Exceptions
  • Tasks and the Task State Segment (TSS)
  • Interrupt Descriptor Table (IDT)
  • Interrupt Descriptors
  • Interrupt masking
  • Red Pill and virtualization detection


System Calls

  • System Call instructions (syscall/sysret, sysenter/sysexit)
  • Syscall-adjacent techniques & instructions (swapgs, {rd,wr}{fs,gs}base)


Read the Time Stamp Counter (RDTSC)


Paging and Virtual Memory

  • Introduction
  • Paging and the Control Registers
  • Page Tables
  • – 32 bit linear to 32 bit physical, 4KB pages
  • – 32 bit linear to 32 bit physical, 4MB pages
  • – 32 bit linear to 40 bit physical, Physical Address Extensions (PAE)
  • – 48 bit linear to 52 bit physical, 4-level paging, 4KB, 2MB, 1GB pages
  • – (Optional) 57 bit linear to 52 bit physical, 5-level paging
  • Page Table Entries
  • – CR3
  • – PML4E
  • – Exploit Mitigation Aside: XD, SMEP, SMAP
  • – PDPTE
  • – PDE
  • – PTE
  • Canonical addresses
  • Page faults
  • Translation Lookaside Buffer & Shadow Walker rootkit
  • Non-executable Memory (NX/XD bit)


Interrupts & Debugging

  • Software breakpoints
  • Hardware breakpoints
  • Normal break on execute, write, read/write, port IO
  • Break on mov to debug registers
  • Trap Flag (TF)
  • Resume Flag (RF) and single step exceptions


Port IO

  • In/out instruction and accessing VMWare “backdoor” IO port




Go HERE to take this class as a 4-Day Buffet course.
Go HERE to take this class as a 3-Day Buffet course.
Go HERE to join just the x86-64 assembly class.
Go HERE to join just the x86-64 Intel Firmware Attack & Defense class.

Why You Should Take This Course

This class teaches you about the fundamental hardware mechanisms which all operating systems, virtualization systems, and firmware *must* interact with in order to run successfully on x86 hardware. This is taught in a *mostly* OS-agnostic way focusing on Intel-isms rather than OS-isms (albeit with using Windows as reinforcement, thanks to its excellent kernel-level debugging support.) This class also teaches you to be comfortable with Reading The Fun Manual (RTFM!) to give you self-sufficiency when seeking out the most accurate details of how things work.
You can also opt to attend this class on 23 & 24 Aug instead. To do so, just email sectraininfo@hitb.org
Go HERE to take this class as a 4-Day Buffet course. Go HERE to take this class as a 3-Day Buffet course. Go HERE to join just the x86-64 assembly class. Go HERE to join just the x86-64 Intel Firmware Attack & Defense class.

Who Should Attend

  • People who want to start their journey up the skill tree towards such professions as reverse engineering, malware analyst, vulnerability hunter, security researcher, OS engineer, or systems architect.
  • People who gain satisfaction from understanding how systems really work at a very deep level.
  • People who don’t have a lot of free time outside of work, and who thus want to use this time to hunker down and jam through all this material with full instructor support.

Key Learning Objectives

  • Prerequisite Knowledge

    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 HITB. If you don’t have that background, or if you just need a refresher, you can sign up for the Xeno’s 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.

    Hardware / Software Requirements

    • VMWare (the free “Player” version is fine)
    • A Windows PC capable of running 1 VMWare instance of Windows 10 x86-64. You can use the host OS as the kernel debugger, and the VM as the debugger.
    • A Linux system or an *x86* Mac with capable of running 2x Windows 10 VMWare VMs. One will serve as the debugger, and one as the debuggee.
    • Headphones for watching videos, (preferably over-ear so you’re not disturbed as the instructor is walking around the class answering individuals’ questions).

    Your Instructor

    Xeno began leading Windows kernel-mode rootkit detection and defense research projects at MITRE in 2009, before moving into research on BIOS security in 2011. His team’s first public talks started appearing in 2013, which led to a flurry of presentations on BIOS-level vulnerabilities up through 2014. In 2015 he co-founded LegbaCore.

    And after presenting a firmware worm that could spread between Macs via Apple’s EFI-based BIOS and Thunderbolt Ethernet adapters, he ended up working for Apple. There he worked on securing all the lesser-known firmwares on Macs and peripherals – everything from 3rd party GPUs to SecureBoot for monitors! He also worked on the x86-side of the T2 SecureBoot architecture, and his final project was leading the M1 SecureBoot architecture – being directly responsible for designing a system that could provide iOS-level security, while still allowing customer choice to trust arbitrary non-Apple code such as Linux bootloaders. He left Apple in Dec 2020 after the M1 Macs shipped, so he could work full time on OpenSecurityTraining2