Book Image

Learning Linux Binary Analysis

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

Learning Linux Binary Analysis

5 (1)
By: Ryan "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 (17 chapters)
Learning Linux Binary Analysis
Credits
About the Author
Acknowledgments
About the Reviewers
www.PacktPub.com
Preface
Index

ELF virus parasite infection methods


There are only so many places to fit code in a binary, and for any sophisticated virus, the parasite is going to be at least a few thousand bytes and will require enlarging the size of the host executable. In ELF executables, there aren't a whole lot of code caves (such as in the PE format), so you are not likely to be able to shove more than just a meager amount of shellcode into existing code slots (such as areas that have 0s or NOPS for function padding).

The Silvio padding infection method

This infection method was conceived by Silvio Cesare in the late '90s and has since shown up in various Linux viruses, such as Brundle Fly and the POCs produced by Silvio himself. This method is inventive, but it limits the infection payload to one page size. On 32-bit Linux systems, this is 4096 bytes, but on 64-bit systems, the executables use large pages that measure 0x200000 bytes, which allows for about a 2-MB infection. The way that this infection works is by...