Book Image

Fuzzing Against the Machine

By : Antonio Nappa, Eduardo Blázquez
Book Image

Fuzzing Against the Machine

By: Antonio Nappa, Eduardo Blázquez

Overview of this book

Emulation and fuzzing are among the many techniques that can be used to improve cybersecurity; however, utilizing these efficiently can be tricky. Fuzzing Against the Machine is your hands-on guide to understanding how these powerful tools and techniques work. Using a variety of real-world use cases and practical examples, this book helps you grasp the fundamental concepts of fuzzing and emulation along with advanced vulnerability research, providing you with the tools and skills needed to find security flaws in your software. The book begins by introducing you to two open source fuzzer engines: QEMU, which allows you to run software for whatever architecture you can think of, and American fuzzy lop (AFL) and its improved version AFL++. You’ll learn to combine these powerful tools to create your own emulation and fuzzing environment and then use it to discover vulnerabilities in various systems, such as iOS, Android, and Samsung's Mobile Baseband software, Shannon. After reading the introductions and setting up your environment, you’ll be able to dive into whichever chapter you want, although the topics gradually become more advanced as the book progresses. By the end of this book, you’ll have gained the skills, knowledge, and practice required to find flaws in any firmware by emulating and fuzzing it with QEMU and several fuzzing engines.
Table of Contents (18 chapters)
Part 1: Foundations
Part 2: Emulation and Fuzzing
Part 3: Advanced Concepts
Chapter 12: Conclusion and Final Remarks

Emulating an embedded firmware

As we attempt to emulate real-time firmware, such as a baseband kernel running on an ARM Cortex-R7 processor, we will encounter the challenges of creating an emulator that faithfully replicates the original execution as closely as possible.

If we download an example firmware image from and extract it, we can use xxd -g 4 on modem.bin to understand the basic structure of the firmware of the baseband modem of the G973 Phone (Galaxy S10). The text in bold shows the meaning of the various blocks. The TOC section (starting with the 544f43 ASCII) uses the first 96 bits (12 bytes) for the entry name, and the next 4 bytes are used for the file offset within modem.bin. Following that, we have the 0x800040 value, which is the load address in memory; since we have it in little endian, the load address will eventually...