Book Image

Learning Linux Binary Analysis

By : "elfmaster" O'Neill
5 (1)
Book Image

Learning Linux Binary Analysis

5 (1)
By: "elfmaster" O'Neill

Overview of this book

Learning Linux Binary Analysis is packed with knowledge and code that will teach you the inner workings of the ELF format, and the methods used by hackers and security analysts for virus analysis, binary patching, software protection and more. This book will start by taking you through UNIX/Linux object utilities, and will move on to teaching you all about the ELF specimen. You will learn about process tracing, and will explore the different types of Linux and UNIX viruses, and how you can make use of ELF Virus Technology to deal with them. The latter half of the book discusses the usage of Kprobe instrumentation for kernel hacking, code patching, and debugging. You will discover how to detect and disinfect kernel-mode rootkits, and move on to analyze static code. Finally, you will be walked through complex userspace memory infection analysis. This book will lead you into territory that is uncharted even by some experts; right into the world of the computer hacker.
Table of Contents (11 chapters)
10
Index

Identifying protected binaries


Identifying a protected binary is the first step in reverse-engineering it. We discussed the common anatomy of protected ELF executables in Chapter 5, Linux Binary Protection. Remember from what we learned that a protected binary is actually two executables that have been merged together: you have the stub executable (the decryptor program) and then the target executable.

One program is responsible for decrypting the other, and it is this program that is going to typically be the wrapper that wraps or contains an encrypted binary within it, as a payload of sorts. Identifying this outer program that we call a stub is typically pretty easy because of the blatant oddities you will see in the program header table.

Let's take a look at a 64-bit ELF binary that is protected using a protector I wrote in 2009 called elfcrypt:

$ readelf -l test.elfcrypt

Elf file type is EXEC (Executable file)
Entry point 0xa01136
There are 2 program headers, starting at offset 64

Program...