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

Identifying text segment padding infections


This type of infection is relatively easy to detect. This type of infection was also discussed in Chapter 4, ELF Virus Technology – Linux/Unix Viruses. This technique relies on the fact that there is always going to be a minimum of 4,096 bytes between the text and the data segment because they are loaded into memory as two separate memory segments, and memory mappings are always page aligned.

On 64-bit systems, there is typically 0x200000 (2MB) free due to PSE (Page size extension) pages. This means that a 64-bit ELF binary can be inserted with a 2MB parasite, which is much larger than what is typically needed for an injection space. With this type of infection, like any other, you can often identify the parasite location by examining the control flow.

With the lpv virus which I wrote in 2008, for instance, the entry point is modified to start execution at the parasite that is inserted using the text segment padding infection. If the executable...