Digital Evidence and Computer Crime: Forensic Science, Computers, and the Internet / Edition 3

by Eoghan Casey

Overview

Digital evidence—evidence that is stored on or transmitted by computers—can play a major role in a wide range of crimes, including homicide, rape, abduction, child abuse, solicitation of minors, child pornography, stalking, harassment, fraud, theft, drug trafficking, computer intrusions, espionage, and terrorism.
Though an increasing number of criminals are using computers and computer networks, few investigators are well-versed in the evidentiary, technical, and legal issues related to digital evidence. As a result, digital evidence is often overlooked, collected incorrectly, and analyzed ineffectively. The aim of this hands-on resource is to educate students and professionals in the law enforcement, forensic science, computer security, and legal communities about digital evidence and computer crime.
This work explains how computers and networks function, how they can be involved in crimes, and how they can be used as a source of evidence. As well as gaining a practical understanding of how computers and networks function and how they can be used as evidence of a crime, readers will learn about relevant legal issues and will be introduced to deductive criminal profiling, a systematic approach to focusing an investigation and understanding criminal motivations.
The accompanying CD-ROM contains simulated cases that integrate many of the topics covered in the text, teaching individuals about:
* Components of computer networks
* Use of computer networks in an investigation
* Abuse of computer networks
* Privacy and security issues on computer networks
* The law as it applies to computer networks

"This is the right book for the times."

—Lori Fenna, Chair, Electronic Frontier Foundation

"I had the enjoyable task of reviewing the galley proofs for Eoghan Casey's fine introductory book: Digital Evidence and Computer Crime recently, and I highly recommend it for anybody who is just entering the field of digital forensics.
This book has many fine features, including coverage of the basics of criminal investigation, legal issues in digital forensics, and of course, the technical information you need to get started in the field and understand what the experts are talking about. It covers the who, what, why, when, where, and how of digital evidence, addresses means, motive, and opportunity, and addresses the big picture issues very well. While I wouldn't take it on-scene, I think it is a valuable resource and well suited as a text for a first courses in digital forensics, or as a general reference for the field as it exists today. Regardless of whether your background is in the law, criminal investigation, or computers, this book is a useful resource.
I was particularly enamored with the number of examples included in the book. These case studies and situational demonstrations bring the book to life and add meaning that you can't get from a dry academic book, regardless of its coverage of details. The notions of remembering the victim and their link to the crime, the descriptions of complexities associated with Internet crime and globalization, and the concepts of investigation and sleuthing help the reader understand the difference between investigation and academics.
But Casey doesn't stop there. He goes on to include an extensive glossary, excellent citations, a useful index, sample printouts, URLs of well known sites, and a multimedia supplement (which was not available at the time of my review). All told, this book does a fine job of introducing the area and provides a useful resource for the active practitioner."
—Fred Cohen, Sandia National Laboratories, Livermore, California, U.S.A.

"This book addresses a diverse audience: law enforcement people who collect evidence, forensics scientists who perform analyses, lawyers who provide legal counsel, and technical people such as computer security professionals, programmers, and system administrators who can be called upon to produce digital evidence.
Digital Evidence gives an introduction to concepts from computer science (computer architecture, protocols, applications), forensics science (recovering, reconstructing and analyzing evidence), and behavioral analysis (modus operandi, motivation, what makes an offender choose a specific victim or target). For those who wish to know more, the book gives references to specialized literature and on-line resources. The sections on legal issues are a bit U.S.-specific, but can still be of interest to non-U.S. readers. To the investigator, the book gives a flavor of what it takes to examine a PC, MAC, NT or UNIX system, or to gather evidence at various layers of network protocols, including wireless networks. With computers, emphasis is on capturing disk information. With computer networks, emphasis is on the application layer: web, mail, news, and irc/icq. The book gives examples of common forgeries with email and usenet postings, and mentions IP spoofing without going into the technicalities.
To the legal person, the book gives a flavor of the challenges that one has to face when gathering digital evidence. Especially with information retrieved across networks it can be difficult to prove that data is authentic. And as the email and usenet examples show, it is relatively easy to forge time stamp and/or address information, but the book also shows that it is relatively easy to be found out.
Perhaps the most useful sections of the book are the ones with guidelines for how to perform specific investigations."
—Wietse Venema, IBM T.J. Watson Research Center, U.S.A.

Product Details

ISBN-13:	2900123742680
Publication date:	04/20/2011
Edition description:	NE
Pages:	840
Product dimensions:	7.90(w) x 9.30(h) x 1.90(d)

About the Author

Eoghan Casey is an internationally recognized expert in data breach investigations and information security forensics. He is founding partner of CASEITE.com, and co-manages the Risk Prevention and Response business unit at DFLabs. Over the past decade, he has consulted with many attorneys, agencies, and police departments in the United States, South America, and Europe on a wide range of digital investigations, including fraud, violent crimes, identity theft, and on-line criminal activity. Eoghan has helped organizations investigate and manage security breaches, including network intrusions with international scope. He has delivered expert testimony in civil and criminal cases, and has submitted expert reports and prepared trial exhibits for computer forensic and cyber-crime cases.

In addition to his casework and writing the foundational book Digital Evidence and Computer Crime, Eoghan has worked as R&D Team Lead in the Defense Cyber Crime Institute (DCCI) at the Department of Defense Cyber Crime Center (DC3) helping enhance their operational capabilities and develop new techniques and tools. He also teaches graduate students at Johns Hopkins University Information Security Institute and created the Mobile Device Forensics course taught worldwide through the SANS Institute. He has delivered keynotes and taught workshops around the globe on various topics related to data breach investigation, digital forensics and cyber security.

Eoghan has performed thousands of forensic acquisitions and examinations, including Windows and UNIX systems, Enterprise servers, smart phones, cell phones, network logs, backup tapes, and database systems. He also has information security experience, as an Information Security Officer at Yale University and in subsequent consulting work. He has performed vulnerability assessments, deployed and maintained intrusion detection systems, firewalls and public key infrastructures, and developed policies, procedures, and educational programs for a variety of organizations. Eoghan has authored advanced technical books in his areas of expertise that are used by practitioners and universities around the world, and he is Editor-in-Chief of Elsevier's International Journal of Digital Investigation.

Read an Excerpt

Chapter 3: Modus Operandi, Motive and Technology

This can take the form of misusing and abusing department resources and violating the public trust, including but not limited to things like inappropriate telephone charges, vehicle use, and desertion of one's assigned duties. And we are not talking about small misallocations, but rather large ones such as in the example, which are symptomatic of ongoing patterns of departmental resource misuse and abuse.

As in Example 2, criminal activity in these instances can also take on the form of the distribution of pornographic materials (an officer allegedly e-mailed a digital photograph of his genitals to the 17-year-old girl), which, depending on the circumstances, can have serious legal consequences.

In both examples, technology facilitated criminal behavior in terms of providing both the mechanisms for initial contact between the involved parties, and a means for communication and illicit materials sharing between the parties over great distances. But as we have shown, less complex and "immediate" technologies do exist which have facilitated the same type of behavior in the past.

A more reactive aspect of the relationship between MO and technology, from the criminal's point of view, involves the relationship between the advancement of crime detection technologies in the forensic sciences, and a criminal's knowledge of them.

Successful criminals are arguably those who avoid detection and identification, or at the very least capture. The problem for criminals is that as they incorporate new and existing technologies into their MO which make their criminal behavior or identity more difficult to detect, theforensic sciences have made advances to become more competent at crime detection. Subsequently, criminals that are looking to make a career, or even a hobby, for themselves with their illegal activity must rise to the meet that challenge. That is to say, as criminals learn about new forensic technologies and techniques being applied to their particular area of criminal behavior, they must be willing to modify their MO, if possible, in order to circumvent those efforts.

But even an extremely skillful, motivated, and flexible offender may only learn of a new forensic technology when it has been applied to one of their crimes and resulted in their identification and/or capture. While this encounter can teach them something that they may never forget in the commission of future crimes, in such cases the damage will already have been done.

This text is replete with examples of such instances, so we will not adduce specifics in this chapter.

Motive and Technology

The term motive refers to the emotional, psychological, or material need that impels, and is satisfied by, a behavior (Turvey 1999). Criminal motive is generally technology independent. That is to say, the psychological or material needs that are nurtured and satisfied by a criminal's pattern of behavior tend to be separate from the technology of the day. The same motives that exist today have arguably existed throughout recorded history, in one form or another. However, it may also be argued that existing motives (i.e. sexual fetishes) can evolve with the employment of, or association of, offense activities with specific technologies. Towards understanding these issues, this section will demonstrate how an existing behavioral motivational typology may be applied within the context of computer- and Internetrelated criminal behavior.

In 1979, A. Nicholas Groth, an American clinical psychologist working with both victims and offender populations, published a study of over 500 rapists. In his study, he found that rape, like other crimes involving behaviors that satisfy emotional needs, is complex and multi-determined. That is to say, the act of rape itself serves a number of psychological needs and purposes (motives) for the offender. The purpose of his work was clinical, to understand the motivations of rapists for the purpose of the development of effective treatment plans (Groth 1979).

Eventually the Groth rapist motivational typology was taken and modified by the FBI's National Center for the Analysis of Violent Crime (NCAVC) and its affiliates (Hazelwood et al. 1991; Burgess and Hazelwood 1995).

This author has found, through casework, that this behaviorally based motivational classification system, with some modifications, is useful for understanding the psychological basis for most criminal behavior. The basic psychological needs, or motives, that impel human criminal behaviors remain essentially the same across different types of criminals, despite their behavioral expression, which may involve computer crimes, stalking, harassment, kidnapping, child molestation, terrorism, sexual assault, homicide, and/or arson. This is not to say that the motivational typology presented here should be considered the final word in terms of all specific offender motivations. But in terms of general types of psychological needs that are being satisfied by offender behavior, they are fairly inclusive, and fairly useful.

Below, the author gives a proposed behavioral motivational typology (Turvey 1999), and examples, adapted from Burgess and Hazelwood (1995), with some input from Geberth (1996). This author takes credit largely for the shift in emphasis from classifying offenders - to classifying offense behaviors (turning it from an inductive labeling system to a deductive tool)...

Table of Contents

1.	Introduction to Digital Evidence	1
2.	The Language of Cybercrime	15
3.	Modus Operandi, Motive and Technology	25
4.	Applying Forensic Science to Computers	41
5.	Digital Evidence on Computer Networks	75
6.	Digital Evidence on the Internet	99
7.	Digital Evidence at the Transport and Network Layers	121
8.	Digital Evidence on the Data-Link and Physical Layers	145
9.	Using Digital Evidence and Behavioral Evidence Analysis in an Investigation	161
10.	Computer Crackers	171
11.	Cyberstalking	187
12.	Digital Evidence as Alibi	199
13.	Laws, Jurisdiction, Search and Seizure	207
14.	Thoughts for the Future	223
Appendix 1	Summary of Resources	231
Appendix 2	Multimedia Supplement	243

Editorial Reviews

"Throughout the book there are a number of good case studies used to illustrate points which enlivens the text. There are also details of legal cases from various legislative areas and examples of relevant situations that demonstrate the points being made. There are also a number of references to other literature and links to website URLs and tools available to assist the practitioner."—Best Digital Forensics Book in InfoSecReviews Book Awards

"Just finished ‘Digital Evidence and Computer Crime: Forensic Science, Computers and the Internet’ by Eoghan Casey and featuring other contributing authors, and it’s quite good. I bought this book because I wanted an all-encompassing book that provided insight on the various aspects of an investigation, especially the legal portion. And in this aspect the book does an excellent job, and is in-depth in area’s I have yet to see in other books. The book is divided into five portions digital forensics, digital investigations, apprehending offenders, computers and network forensics. For me the book was worth it for the first three portions; however, the computers and network portions, while a good start, there are more in-depth books that provide better insight… Overall, the book was enjoyable from start to finish and I would recommend it to anyone looking for a great overview of digital forensic investigation process from start to finish. I am happy to add this book to my growing reference library."—Student of Security

"This hefty book on forensic evidence obtained from computers dispels the myths propagated by popular television series. It states from the premise that very few people are well versed in the technical, evidential, and legal issues concerning digital evidence. Oftentimes, the useful evidence that may be found in various digital media is overlooked, collected incorrectly, or analyzed ineffectively. It is the goal of the team of contributors to equip readers with the necessary knowledge and skills to be able to make use of digital evidence correctly and effectively….  It is quite obvious that the various authors draw from several fields, such as forensic science, computer science, political science, criminal justice, the law, and behavioral analysis; as such, it is multi- and interdisciplinary. More specifically, the authors tackle the specific crimes of cyber bullying, cyber stalking, identity theft, online sex offenders, fraudsters, and cyber threats. There is extensive use of boxed stories, legal cases, practitioner’s tips, tables, the discussion of legislation, flow charts, treaties and journals, as well as figures, diagrams, pictures, and computer screen shots. The book is comparative in nature: it covers not only cyber law in the US, but also case law in the UK, Ireland, and the Netherlands. Given the ubiquity of the computer and the crimes that it can generate, learning about how other nations handle these issues helps in the formation of our own methods for dealing with crimes domestically, as well as those that cross national boundaries."—ACM’s Computing Reviews.com

"A better title for Digital Evidence and Computer Crime might be the Comprehensive Guide to Everything You Need to Know About Digital Forensics. One is hard pressed to find another book overflowing with so many valuable details and real-world examples."—Ben Rothke on Slashdot.org (Sept 2011)

"The third edition of this comprehensive textbook on forensic science and the Internet is thoroughly updated to reflect the great leaps forward in technology in the six years since the previous printing. The work is divided into five sections covering digital forensics, digital investigations, apprehending offenders, computers and network forensics, and chapters provide practical instruction, case studies and discussions of the theoretical basis for all aspects of digital investigation and the use of computer evidence in forensics and law enforcement. The volume is intended for police, lawyers and forensic analysts and provides a comprehensive look at contemporary methodologies computer crime and crime prevention. Contributors include legal academics as well as computer, networking and forensics professional from around the world."—Book News, Reference & Research

"A better title for Digital Evidence and Computer Crime might be the Comprehensive Guide to Everything You Need to Know About Digital Forensics. One is hard pressed to find another book overflowing with so many valuable details and real-world examples. The book is also relevant for those who are new to the field, as it provides a significant amount of introductory material that delivers a broad overview to the core areas of digital forensics. The book progresses to more advanced and cutting-edge topics, including sections on various operating systems, from Windows and Unix to Macintosh. This is the third edition of the book and completely updated and reedited. When it comes to digital forensics, this is the reference guide that all books on the topic will be measured against. With a list price of $70.00, this book is an incredible bargain given the depth and breadth of topics discussed, with each chapter written by an expert in the field. For those truly serious about digital forensics, Digital Evidence and Computer Crime is an equally serious book."—Slashdot.com

From the Publisher