Cover image for Computer forensics : incident response essentials
Computer forensics : incident response essentials
Kruse, Warren G.
Personal Author:
Publication Information:
Boston, MA : Addison-Wesley, [2002]

Physical Description:
xiii, 392 : illustrations ; 24 cm
Added Author:
Format :


Call Number
Material Type
Home Location
Item Holds
QA76.9.A25 K78 2002 Adult Non-Fiction Central Closed Stacks

On Order



Every computer crime leaves tracks--you just have to know where to find them. This book shows you how to collect and analyze the digital evidence left behind in a digital crime scene.

Computers have always been susceptible to unwanted intrusions, but as the sophistication of computer technology increases so does the need to anticipate, and safeguard against, a corresponding rise in computer-related criminal activity.

Computer forensics, the newest branch of computer security, focuses on the aftermath of a computer security incident. The goal of computer forensics is to conduct a structured investigation to determine exactly what happened, who was responsible, and to perform the investigation in such a way that the results are useful in a criminal proceeding.

Written by two experts in digital investigation, Computer Forensics provides extensive information on how to handle the computer as evidence. Kruse and Heiser walk the reader through the complete forensics process--from the initial collection of evidence through the final report. Topics include an overview of the forensic relevance of encryption, the examination of digital evidence for clues, and the most effective way to present your evidence and conclusions in court. Unique forensic issues associated with both the Unix and the Windows NT/2000 operating systems are thoroughly covered.

This book provides a detailed methodology for collecting, preserving, and effectively using evidence by addressing the three A's of computer forensics:

Acquire the evidence without altering or damaging the original data. Authenticate that your recorded evidence is the same as the original seized data. Analyze the data without modifying the recovered data.

Computer Forensics is written for everyone who is responsible for investigating digital criminal incidents or who may be interested in the techniques that such investigators use. It is equally helpful to those investigating hacked web servers, and those who are investigating the source of illegal pornography.


Author Notes




Preface Billions of dollars are lost annually to crime, and computers are increasingly involved. It is clear that law enforcement agencies need to investigate digital evidence, but does it make sense to encourage a bunch of computer administrators to become junior g-men? Do we really need amateur digital sleuths? In a word, yes. Bad things are happening on computers and to computers, and the organizations responsible for these computers have a need to find out what exactly happened. You probably cannot pick up the phone and bring in law enforcement officials every time something anomalous happens on one of your servers and expect them to send out a team of forensic specialists, and even if you could, your corporate executives may not want that. All major corporations have internal security departments that are quite busy performing internal investigations. However, the security professionals who typically fill this role are accustomed to dealing with theft and safety issues and are often ill-prepared to deal with computer crime. This book is inspired by the needs of the people who attend the author's seminars on computer forensics. If for no other reason than these sold-out seminars, we know that there is a big demand for greater expertise in digital investigations. System administrators and corporate security staff are the people we've designed the book for. Most of the seminar attendees are fairly skilled in the use and maintenance of Microsoft environments. Some of them are Unix specialists, but many students have expressed a strong desire to learn more about Unix. Once a corporation discovers that they know someone who can investigate Windows incidents, it is assumed that he or she knows everything about computers, and it is usually only a matter of time until this person is pressured into taking a look at a suspect Unix system. Our students come from a wide variety of backgrounds and have diverse investigatory needs and desires. We try to accommodate these varying agendas in this book, to which we bring our experience in investigation and incident response. Warren Kruse is a former police officer who regularly performs computer forensic examinations inside and outside of Lucent Technologies. Jay Heiser is an information security consultant who has been on the response teams for numerous hacked Internet servers. To the maximum extent possible, this book contains everything useful that we've learned from performing investigations and teaching others to do so for themselves. We know what questions will be asked, and this book is designed to answer them. It is a practical guide to the techniques used by real people to investigate real computer crimes. How to Read This Book This book can be read cover to cover, as a complete introductory course in computer forensics. However, it is also meant to serve as a handbook, and we expect many readers to be familiar with some of the subjects we cover. For that reason, each chapter is a complete unit and can be read when convenient or necessary. You probably specialize in one or more of the areas covered in this text. However, we believe that the information presented in this book is at the minimum required level of legal and computer literacy, and we urge you to become knowledgeable in all of the areas we cover: legal, procedural, and technical. A brief description of the information covered in each chapter is provided in the sections that follow. Introduction to Computer Forensics Chapter 1 outlines the basic process of evidence collection and analysis, which is the meat of computer forensics. Even those readers with a background in law enforcement will find new techniques in this chapter that are specific to computer forensics. Tracking an Offender The Internet is pervasive, and a high percentage of your investigations will involve either incoming or outgoing Internet traffic. The material in Chapter 2 will help you interpret the clues inside of email messages and news postings. It will also start you on the path toward becoming an Internet detective, using standard Internet services to perform remote investigations. The Basics of Hard Drives and Storage Media For the computer sleuth, hard drives are the most significant containers of evidence. Chapter 3 provides an understanding of both their logical and their physical configurations. It covers partitions and low-level formatting, filesystems, and hardware drive interfaces. Encryption and Forensics Cryptography has become ubiquitous in the virtual world of the Internet. A skilled investigator must have a solid understanding of the technology and goals of modern cryptography. It is relevant both in understanding evidence and, interestingly, in the preservation of evidence. Many investigators lack a necessary level of crypto-literacy, so Chapter 4 provides a broad introduction to encryption with special emphasis on its significance and application in computer forensics. We also discuss common encoding and archiving formats (such as uuencode and PKZIP) that can complicate your keyword searches. As digital signature technology grows in legal significance and finds new uses, forensic investigators will be expected to understand its limitations and must have a firm grasp of the ways in which a digital identity can be stolen. The digital timestamping of forensic evidence will soon become standard procedure in digital investigations. If you already have a background in these encryption concepts, then you may wish to skim this chapter. Data Hiding Being able to find hidden data is a crucial investigative skill. Even if you are highly crypto-literate, you still may not be aware of steganography (the art of hiding information by embedding covert messages within other messages) and other data-hiding techniques. Continuing the subject of encryption, Chapter 5 describes the use of specific password-cracking tools that we have successfully used during our investigations. This chapter categorizes and describes the ways that data can be hidden--not just by encryption--and provides practical guidance on how to find and read hidden data. Hostile Code Being able to identify and understand the implications of criminal tools is a skill that every investigator needs. Given that hostile code can be arcane and that few readers have a background in it, Chapter 6 provides an introduction to the topic and an overview of the types and capabilities of digital criminal tools that the investigator may encounter. We've included a couple of war stories involving the recent use of "hacker tools" on corporate PCs, which is becoming increasingly common. Your Electronic Toolkit Although forensic-specific tools have a certain James Bond--like appeal--and we cover these products--a large percentage of your work will be done with system tools that were not specifically created for the unique needs of forensic investigation. Chapter 7 will introduce you to a wide variety of utility types and specific brand name tools, along with instructions in their use in a digital investigation. Investigating Windows Computers Microsoft Windows, in all its various flavors, is the most widely used family of operating systems. While Chapter 8 assumes some background in Windows, you don't need to be a Microsoft Certified Systems Engineer in order to apply the techniques and tricks we discuss. Emphasis is placed on Windows NT 4.0 and Windows 9x, but several important new Windows 2000 features, such as the Encrypting File System, are covered. An experienced investigator soon learns that nothing is too obsolete to be in daily use somewhere, so the chapter concludes with Windows 3.1--specific material. Introduction to Unix for Forensic Examiners For those readers with no prior Unix experience, Chapter 9 provides an introduction with special emphasis on Unix characteristics that are most significant for the forensic investigator. Experienced Unix users can skim or skip this chapter. Compromising a Unix Host Chapter 10 is intended as background material for the investigation of hacked Internet hosts. It describes the process that Unix attackers typically use and provides an understanding of the goals of typical system hackers. Investigating a Unix Host While emphasizing the investigation of hacked Unix hosts, Chapter 11 describes techniques that are applicable to all forms of Unix investigation. It contains a detailed set of Unix-specific techniques and processes that use common Unix utilities for collecting and evaluating evidence. It also contains instructions on using a Unix boot CD to capture information over a network when you can't attach hardware directly to a suspect system. Introduction to the Criminal Justice System The final chapter explains what you need to do after you have begun collecting evidence and provides an overview of the criminal justice process. Legal concepts such as affidavits, subpoenas, and warrants are described. You will be a more effective interface between your organization and law enforcement agents if you understand what they do and how both investigations and prosecutions are structured by the legal system. Appendixes As in most books, the appendixes in this one contain information that doesn't fit neatly anywhere else. They are standalone guides to specific needs. Appendix A, Internet Data Center Response Plan, defines a process for handling computer security incidents in Internet Data Centers. Appendix B, Incident Response Triage, provides a list of general questions that should be asked during the investigation of a computer crime incident. Appendix C, How to Become a Unix Guru, provides self-study suggestions for forensic examiners who want to improve their ability to investigate Unix hosts. Appendix D, Exporting a Windows 2000 Personal Certificate, graphically depicts the process of exporting a Personal Certificate from a Windows 2000 computer. Investigators should practice this process to prepare themselves for incidents involving the Encrypted File System. Appendix E, How to Crowbar Unix Hosts, describes the process of gaining administrative access to a Unix system by booting it from a floppy or CD. Appendix F, Creating a Linux Boot CD, provides several suggestions on techniques and technology sources that are useful in the creation of bootable Linux CDs that can be used to crowbar Unix or NT systems. Booting from a Linux CD can also provide a trusted environment useful for examining or collecting evidence when it is not feasible to remove the hard drive from a system. Appendix G, Contents of a Forensic CD, provides a shopping list of useful tools that should be considered the minimum set of forensic utilities that an examiner brings during an incident response. 0201707195P09182001 Excerpted from Computer Forensics: Incident Response Essentials by Jay G. Heiser, Warren G. Kruse All rights reserved by the original copyright owners. Excerpts are provided for display purposes only and may not be reproduced, reprinted or distributed without the written permission of the publisher.

Table of Contents

Prefacep. vii
Acknowledgmentsp. xiii
Chapter 1 Introduction to Computer Forensicsp. 1
Chapter 2 Tracking an Offenderp. 23
Chapter 3 The Basics of Hard Drives and Storage Mediap. 65
Chapter 4 Encryption and Forensicsp. 83
Chapter 5 Data Hidingp. 105
Chapter 6 Hostile Codep. 129
Chapter 7 Your Electronic Toolkitp. 149
Chapter 8 Investigating Windows Computersp. 177
Chapter 9 Introduction to Unix for Forensic Examinersp. 207
Chapter 10 Compromising a Unix Hostp. 245
Chapter 11 Investigating a Unix Hostp. 263
Chapter 12 Introduction to the Criminal Justice Systemp. 311
Chapter 13 Conclusionp. 325
Appendix A Internet Data Center Response Planp. 327
Appendix B Incident Response Triage Questionnairep. 353
Appendix C How to Become a Unix Gurup. 363
Appendix D Exporting a Windows 2000 Personal Certificatep. 367
Appendix E How to Crowbar Unix Hostsp. 375
Appendix F Creating a Linux Boot CDp. 377
Appendix G Contents of a Forensic CDp. 379
Annotated Bibliographyp. 381
Indexp. 385