Hypervisor Development for Security Analysis
Satoshi Tanda

Levels

• Intermediate to advanced

Prerequisites

Required:

• Strong experience in C (or C++) programming.
• Familiarity with the x86_64 architecture, such as privilege levels, interrupts, page tables, and system registers.
• System programming experience, such as kernel-module development, is a plus but not a requirement.

Recommended pre-class learning materials will be introduced about prior to the class.

Learning Objectives

At the end of the class, students will gain enough knowledge and skills to start developing their pass-through UEFI-based hypervisors. Knowledge-wise, this includes but not limited to the understanding of:

• Key concepts of VT-x and programming interfaces
• General UEFI-module development workflow and tools
• Execution environment changes during OS boot and their influence on the hypervisor design
• Subtle yet critical technologies such as memory types and caches
• Application Processors (APs) start up, and emulation by a hypervisor
• “Owning” control registers and challenges with it
• Various application of hypervisors (for adding security, reverse engineering and fuzzing, for example)

Outlines

Contents may change in a way that does not impact the learning objectives.

Details

A hypervisor is a critical component in both security and cloud computing. There is also an increasing interest in applying virtualization technologies in the area of security engineering and analysis. How can hypervisors be used to secure the existing systems? How to write custom hypervisors to perform reverse engineering and fuzzing more efficiently?

In this class, the students will learn the foundations to answer those questions, that is, the basic skills and knowledge to develop hypervisors. The class is designed in a way such that everything is built from scratch and optimized for learning. This allows students to better understand the building blocks and expand the knowledge acquired in the course by themselves afterward. Topics include UEFI architecture and programming, VT-x/EPT configuration, debugging tools, comparison of hypervisor designs, application of the technologies, and more.

This is a hands-on-oriented class. We believe that the students can learn and retain concepts and skills the best by working with those concepts by themselves and not by being taught; hence gaining the greatest value. With this philosophy, the class is designed for lab activities as the primary learning opportunities, and lectures are to explain backgrounds and the motivations for those. We will spend about half of the time for hands-on.

At the beginning of the class, students will receive skeleton implementations of our hypervisors and incrementally update them through the exercises with a clear understanding of motivations and design choices.

At the end of the class, students will also receive a full version of our hypervisor. This includes implementation of advanced concepts, such as stealth-hooking hypercall, use of VT-d, guest hardening (like HyperGuard if you are familiar with it), host hardening through CET, SMAP, UMIP, etc, handling of uncommon events like microcode update, NMI, and so on. This version can be used to complement your understanding of advanced topics and as a reference to explore more topics as you wish.

Additionally, a proof-of-concept implementation of taking and reverting to snapshots for fast full-system fuzzing will be shared as well.

Hardware and Software Requirements

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