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

The science of detecting entry point modification


When a binary is modified in some way, it is generally for the purpose of adding code to the binary and then redirecting execution flow to that code. The redirection of execution flow can happen in many places within the binary. In this particular case, we are going to examine a very common technique used when patching binaries, especially for viruses. This technique is to simply modify the entry point, which is the e_entry member of the ELF file header.

The goal is here to determine whether or not e_entry is holding an address that points to a location that signifies an abnormal modification to the binary.

Note

Abnormal means any modification that wasn't created by the linker itself /usr/bin/ld whose job it is to link ELF objects together. The linker will create a binary that represents normalcy, whereas an unnatural modification often appears suspicious to the trained eye.

The quickest route to being able to detect anomalies is to first know...