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Seeking the Truth from Mobile Evidence

Basic Fundamentals, Intermediate and Advanced Overview of Current Mobile Forensic Investigations

John Bair (Police Detective: City of Tacoma, WA), Part-Time Lecturer: Institute of Technology, University of Washington-Tacoma, WA, United States

Table of Contents

Cover image

Title page

Copyright

Dedication

Foreword

Preface

Acknowledgment

Introduction Part 1. Basic, Fundamental Concepts

Chapter 1. Defining Cell Phone Forensics and Standards

Introduction

Defining Cell Phone Forensics

Chapter Summary Key Points

Chapter 2. Evidence Contamination and Faraday Methods

Introduction

Evidence Contamination

Faraday Origins

Faraday Methods

Chapter Summary Key Points

Chapter 3. The Legal Process—Part 1

Introduction—Chapter Disclosure

The Legal Process

Mobile Network Operators

Mobile Virtual Network Operators

Determining Target Number

Chapter Summary Key Points

Chapter 4. The Legal Process—Part 2

Search Warrant Language

Destructive Court Orders

Chapter Summary Key Points

Chapter 5. The Cellular Network

Introduction to the Cellular Network

Code Division Multiple Access

Global Systems for Mobile Communications and Time Division Multiple Access

Integrated Digital Enhanced Network

Long-Term Evolution

International Mobile Equipment Identity

Mobile Equipment Identifier

Subscriber Identity Module

International Mobile Subscriber Identity

Integrated Circuit Card Identifier

Mobile Identification Number, Mobile Directory Number, and Preferred Roaming List

How a Call Is Routed Through a Global System for Mobile Communications Network

Chapter Summary Key Points

Chapter 6. Subscriber Identity Module

Introduction

SIM Sizes

Internal Makeup

Where Is My Evidence?

SIM Security

Forensic SIM Cloning

Chapter Summary Key Points

Chapter 7. Device Identification

Introduction

Handset Communication Types

The Form Factors

Common Operating Systems

Steps for Device Identification (Free)

Removable Storage

Chapter Summary Key Points

Chapter 8. Triaging Mobile Evidence

Introduction

Devices Powered On

Devices Powered Off

Locked Devices Powered On

Forensic Processing Triage Forms

Chapter Summary Key Points

Chapter 9. The Logical Examination

Introduction—A “Logical” Home

Computer Forensics and Mobile Forensics

Connection Interfaces

Agent or Client

Communication Protocols

Attention Terminal Commands

Port Monitoring

Chapter Summary Key Points

Chapter 10. Troubleshooting Logical Examinations

Introduction

History of Common Problems

Truck and Trailer Analogy

Device Manager

Advanced Tab (Device Manager)

Using Log Files

General Troubleshooting Steps

Chapter Summary Key Points

Chapter 11. Manual Examinations

History

Reasons for the Manual Examination

Hardware Tools for Manual Extractions

Software Solutions

An Alternative Solution to Hardware and Software Vendors

Chapter Summary Key Points

Chapter 12. Report Writing

History—Our Forensic Wheel

A Final Report Example

General Questions to Answer/Include in Your Report

Initial Contact

Device State

Documenting Other Initial Issues (DNA/Prints/Swabbing)

Specific Tools and Versions Used

Listing Parsed Data

Reporting Issues and Anomalies

Validation

Methods of Reporting

Other Formats and Proprietary Readers

Hashing

The Archive Disk

Chapter Summary Key Points

Part 2. Intermediate Concepts

Chapter 13. Physical Acquisitions

History

Flasher Boxes

Pros and Cons—Flasher Box Usage

Bootloaders

Current Popular Boxes

Early Physical Examination Vendors and Tools

MSAB and Cellebrite

Chapter Summary Key Points

Chapter 14. Physical Memory and Encoding

History

NAND and NOR

NAND Blocks, Spare Area, Operation Rules, Wear Leveling, Garbage Collection, and the SQLite Databases

Encoding

Chapter Summary Key Points

Chapter 15. Date and Time Stamps

Introduction “In the Beginning…”

Epoch, GMT, and UTC

Integers

Formats

Chapter Summary Key Points

Chapter 16. Manual Decoding MMS

Introduction—Lab Work

Susteen—SV Strike and Burner Breaker

MMS Carving

Containers for MMS

Chapter Summary Key Points

Chapter 17. Application Data

Introduction—A Last Argument

Applications

Supported Decoding—The Tip of the Iceberg

Database Naming—It Does Not Always Stay Original

Validating Database Content

Sanderson Forensics SQLite Forensic Browser

Write-Ahead Log Files

Journal Files

Blobs and Attachments

Chapter Summary Key Points

Chapter 18. Advanced Validation

Introduction

USB Monitoring—Can You Hear Me Now?

UltraCompare Professional

Chapter Summary Key Points

Part 3. Advanced Concepts

Chapter 19. Android User Enabled Security: Passwords and Gesture

Introduction—Security on Androids

Simple Security Values

The Password Lock

Hashcat

The Pattern Lock (Gesture)

SHA-1 Exercise

Chapter Summary Key Points

Chapter 20. Nondestructive Hardware and Software Solutions

Introduction

MFC Dongle

IP Box

UFED User Lock Code Recovery Tool

Best Smart Tool

FuriousGold

XPIN Clip

Other Methods

Chapter Summary Key Points

Chapter 21. Phone Disassembly and Water-Damaged Phones

Introduction—Holding It All Together

Fastening Methods

Tools Used

Removing Moisture (Water Damage)

Suggestions—Saltwater Exposure

Chapter Summary Key Points

Chapter 22. JTAG (Joint Test Action Group)

Introduction

Joint Test Action Group

How Joint Test Action Group Works

Test Access Port

Molex (Connections)

Joint Test Action Group Issues

Chapter Summary Key Points

Chapter 23. JTAG Specialized Equipment

Introduction—Slow and Deliberant

Pogo Pins and Jigs

Molex Parts

Wires and Wire Harnesses

JTAG Finder

Precise Soldering Units

Hot Glue, Rubber Bands, and Cardboard

Chapter Summary Key Points

Chapter 24. RIFF Box Overview

Introduction

RIFF Box Components

JTAG Manager Software

Saving the Binary Scan

Manual Probing Test Access Ports

RIFF 2 Overview

Software and Driver Install

DLLs and Account Manage

Connector Pinout Locations

General Purpose Input/Output

eMMC/SD Access Tab

Useful Plugins Tab

Advanced Settings

Chapter Summary Key Points

Chapter 25. Z3X Box (Easy JTAG) Overview

Introduction

Easy-JTAG W/Cables and ISP Adaptor

Software and Driver Install

Additional Activations

Easy JTAG Tool (Z3X EasyJtag Box JTAG Classic Suite)

Reading Target Flash

JTAG Finder

Chapter Summary Key Points

Chapter 26. Thermal Chip Removal

Introduction—Chain of Command Knowledge Phenomenon

Steps Involved in Chip-off

Research the Phone and Chip

Is the Chip Encrypted?

Prepping the Board

Using Heat for Memory Removal

Basic Removal Steps When Using Heat

Chapter Summary Key Points

Chapter 27. Nonthermal Chip Removal

Introduction—“Step Away From the Heat”

Removal Through a Cold Process

Removing the Chip From the Board

Milling

Lap and Polishing

ULTRAPOL Basic

Chapter Summary Key Points

Chapter 28. BGA Cleaning

Introduction—Your First Car

Examples From Thermal Use

Equipment Used in Cleaning (Thermal)

Steps Involved in Cleaning (Thermal Removed)

The Re-tinning Process

Reballing

Case Example (Thermal Cleaning) Steps

Chapter Summary Key Points

Chapter 29. Creating an Image

Introduction—Fish On!

Reading the Memory

Using the UP 828 and 828P Programmers

SD Adaptors

DediProg NuProg-E Programmer

Imaging

Regular Expression Searching

Common Email Regular Expressions

Chapter Summary Key Points

Chapter 30. eMMC Reading and In-System Programming

Introduction—Model Building

What Is In-System Programming?

How Does Communication Occur?

Understand eMMC Support Versus ISP

Researching ISP Connections

Probing In-System Programming Connections

Probing Example

Undocumented Phones

Wires and Jumper Boards

Medusa Pro and Octoplus Pro JTAG

Chapter Summary Key Points

Closing Remarks

Index

Copyright

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This book and the individual contributions contained in it are protected under copyright by the Publisher (other than as may be noted herein).

Notices

Knowledge and best practice in this field are constantly changing. As new research and experience broaden our understanding, changes in research methods, professional practices, or medical treatment may become necessary.

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Dedication

This book is dedicated to the thousands of men and women in law enforcement who spend a magnitude of hours each year sifting

through electronic evidence. You may be underappreciated, overlooked, and go unrecognized. The job may require locating

media of innocent children or others who are being victimized, or exploited. There may be expectations on what you can and cannot locate, and a chain of command whom you struggle with for the

logistics needed in your job. I truly appreciate your efforts. I dedicate this book to each of you.

Foreword

Mobile devices and the rich data associated with them have become the single most important source of evidence in virtually every type of investigation. These data commonly include the information stored on removable media and data from backups, installed applications, and the records retained by service providers. Whether the information is being relied on in a corporate environment to protect intellectual property or in civil law to resolve disputes and provide accountability or as part of a criminal investigation to determine guilt or innocence, the reason for examining mobile device evidence is the same—to find important and reliable information that can be used in proper context to help the finders of fact make important decisions.

In Seeking the Truth from Mobile Evidence, John Bair has carefully and thoroughly laid out important foundational concepts, troubleshooting strategies, helpful hints, and expanded analysis considerations. He has also provided suggestions and methods to help practitioners verify and test findings and build trust in the evidence and examination process. While this book is primarily directed toward law enforcement mobile device forensics practitioners, it includes valuable information for anyone who will benefit from an improved knowledge of how and why data associated with mobile devices can be acquired, analyzed, and explained.

Like me, John Bair began his nearly three-decade long career in law enforcement at a time when cell phones, tablets, personal computers, digital cameras, cloud storage, “Apps,” and the Internet had not yet penetrated our lives. We wrote police reports with pencils and paper, we looked up information in books, we exchanged information by printed interoffice memos, and we made telephone calls using

hardwired telephones. As the digital world began infiltrating the real world and criminals began using the same technology to gain an advantage and facilitate their crimes, John was one of the early pioneers in police work who led the way to “figure this stuff out.” As a lifelong learner, John adapted his practice of criminal investigation along with his knack for problem-solving and reverse engineering to leverage mobile device technology and find important evidence. John was not willing to allow important evidence to be locked away and remain unused.

Anyone who knows John quickly realizes that mobile device forensics is not simply a part of his job—it’s his passion. John is an amazingly talented, humble, and generous forensic practitioner who is quick to share his skills, knowledge, research, and experience to help anyone who is seeking the truth. He has always been on the cutting edge of the newest methods without losing sight of the basics. Just as he has done in this book, John has the rare ability to explain complex technical issues. Through the use of examples from his extensive experience, John is able to bring important and meaningful information to levels appropriate for his audience—novice to advanced. He has trained, mentored, and coached countless students of mobile forensics both inside and outside the criminal justice community.

John has written agency policies and crafted technical guidelines, and he has testified extensively in State and Federal courts as an expert witness in mobile device forensics. While some began as reluctant students, John has educated numerous police officers, detectives, prosecutors, defense attorneys, judges, academics, and product developers. As a truly legitimate and committed mobile device “forensic” practitioner, John is obsessed with finding ways to validate, verify, retest, and prove his findings before he is willing to settle on a particular method or outcome. John recognizes and teaches others that the data in themselves are of no value unless they can be trusted and the process replicated. Throughout this book, you will find references to validation and verification that are important for any practitioner for producing defendable and reliable results.

In addition to the great depth of real-world and practical experience that John brings to the subject of criminal investigation, mobile device forensics, and data analysis, he uses easily relatable stories, scenarios, and anecdotes throughout this book to explain important concepts. These examples give relevance and context that help the reader better understand the “why” and “how.” I have found John’s examples useful during my own efforts to craft language for affidavits in support of search warrants; when writing forensic reports; during expert testimony; and when explaining sometimes highly technical concepts to jurors, lawyers, judges, and law enforcement colleagues.

I must admit that I am an old school guy. I prefer printed books that I can hold in my hand and pages I can flip through. I also generally like the content to be in one place. That said this book uses a Companion Site where expanded content for each chapter can be viewed. John has done an excellent job adding helpful screenshots and other content that add additional value to his book. While I was initially skeptical, I think it is very well suited for books like this one and I value having the additional material.

The field of digital forensics, and in particular mobile device forensics, is dynamic and challenging. Each day brings new device models, new operating system versions, new and changing applications, greater storage capacities, new and changing methods of storage, backups, and the frustration that come with locked screens and encryption. While automated commercial forensic tools are very valuable, John emphasizes how important it is for mobile device forensic practitioners to have the ability to know what these tools are not revealing and how these tools and methods may change, not read, or misread user data. Through this book, John Bair will prepare you for a journey to improve your own practice and he will arm you with a technical knowledge and deeper understanding of mobile device forensics.

For those in law enforcement, you know that there is no greater satisfaction than to protect the weak, get justice for the innocent, and to hold bad actors accountable. This is particularly true in cases

involving child sexual exploitation. While advances in technology have brought us greater opportunities to do our jobs, technology has also brought greater threats to civilized societies as well as more opportunities for suspect anonymity, expanded jurisdictional complexities, reduced cooperation from content service providers, and an increased public distrust and scrutiny of the government. As we move forward together, it’s critical that we work to proactively influence new legislation, strive to not create adverse case law, maintain and improve examiner certifications and training, and lead the way for laboratory accreditation and policies in ways that build trust and confidence in our methods and practices. John Bair has worked throughout his career to become a model for best practices, and this book is a guide to help other mobile device forensic practitioners lay down a solid foundation for the future.

Colin Fagan, CFCE, CCME, Detective Sergeant, Digital Evidence Forensic Examiner

July 2017

Preface

It was raining (again). I had traveled from a hot and dry Texas climate to an area that in the first year, I could not seem to get my toes warm. I was now closer to my family and supposedly working for a department that had less crime than El Paso. So far, I had not seen proof of it. I sat alone and sipped on coffee in a park located in an area they called the “Hilltop.” The police radio was silent, as it should be

for 0415 h on a Tuesday morning. It was September 1993. I had passed my probation period and sat alone in a marked police car. In

the next 6 years that followed in my career, I would have no idea that I would be involved in two officer-involved shootings, the latter nearly killing me.

Out of the corner of my eye I watched a dark figure emerge from the south. Whoever he was, he was tall and had a pronounced limp. His left leg did not bend at the knee, and to travel he brought the leg around from behind him, in a small semicircle stride. My window was down, and I was parked under an overhang of a nearby building, trying to stay dry. I could hear that he was talking to himself. I continued to watch him, and as he moved closer, I could see that he was an older male in his late 50s. His conversation turned to singing.

He was directly in front of where I was parked, maybe 50 ft away. He was now under a street lamp that produced glare of reflective

light off the top of a piece of metal coming from his silhouette. I could not see the item entirely, but it was sticking out from his left side. The metal was large and seemed to be even with his head. Whatever the

metal was, it caught my attention, and I turned on my patrol spotlight and shined it directly at him. He jumped and stopped in his tracks, completely startled. It occurred to me that he had never seen my marked police car until that moment. Through the assistance from the spotlight illumination, I could now see why he was limping. I dumped my coffee out the window and started my patrol car.

I turned on my emergency lights as I pulled the police car closer to him. The man never moved, except to extend his arm to block his eyes from the spotlight. I exited the car and asked him to place his hands up, and onto his head. He complied. I had radioed for assistance, and after they arrived, I placed him in handcuffs. Once he was secured, I removed a large sword that was sticking down his left pant leg. It had

extended up nearly another 3 ft above his waist to his head. In all, the sword was over 6 ft in length and probably weighed 20 pounds.

The rain continued to fall, and all of us were getting wet during this contact. He never spoke while I removed this item from his pants. While the instrument he was carrying was being admired by my backup officers, I asked him, “What’s up with the sword you’re carrying around?” He quickly replied, “These aren’t my pants.”

I no longer drive a marked police vehicle, instead an unmarked, underpowered, “detective” vehicle. My hair has turned from brown to gray. I have incurred a few injuries, a skull fracture, and one neck surgery. My oldest child has a child of her own. I no longer patrol city streets while everyone else sleeps. I have been a detective now since April 1999. During my assignment in the homicide unit I noticed gang members were carrying around devices called Nextel’s. That gave me an idea to try and learn something about how they functioned and what could be stored on them.

Now our world has fully embraced technology. So too the individuals who have chosen to commit criminal acts. Understanding just a little bit about our electronic items we all carry around with us can certainly help aid in solving crimes. It’s September 2017. Now, the

“clients” I contact during my course of digital investigations have changed their statement from, “These aren’t my pants” to: “That’s not my phone.”

Thank you for buying this book. My hope, like the title implies, is that it can help you locate the truth in your digital mobile investigations.

John Bair

Acknowledgment

I would like to thank Mike Smith who I first met at the University of Washington, Tacoma (UWT). Mike is a combat veteran, and when I met Mike, he was senior in the IT program attending my Digital Mobile Forensic (level I) course. Mike excelled during the course, as well as the next two. After his graduation, he was hired by UWT to work in their IT department. We stayed in touch, and since Mike had a great understanding of the course content, he was hired to help with the initial editing of this book. Without his help, I am not certain if this would have ever been finished on time.

Another couple of individuals who need acknowledgment also come from the academia field: Professors Robert Friedman and Bryan Goda. I called Robert in the fall of 2013 and asked if I could have a few minutes of his time to present an idea. Robert allowed me to present the concept of creating a lab that was modeled after the Marshal University in Virginia. A few months later I was presenting the first Mobile Forensics course as a beta class at the Tacoma branch of the University of Washington. Since then, Robert has moved to another university, and Professor Bryan Goda took over where Robert left off. Bryan has allowed me to introduce advanced tools, concepts, and methodologies to senior students in the IT program at the Institute of Technology. Bryan continues to invest in new toys for our classes; most importantly, he believes in what I do and treats me as an asset. I appreciate their willingness to create this program, and all the logistical support along the way.

Of course, there is my spouse that I had to neglect in some way or another over the past couple of years. Thank you for being so patient with me. Sorry the fence (and deck) was never painted, the weeds

were not pulled, and the garage looks like a Sanford and Sons episode. Like many other people who write books, I would never been able to finish if you were not around to love and support me. You always provided assistance simply by listening, even when I was boring you to tears most of the time.

Then there is my Dad. He will never be able to read this book, but he was certainly alive with me as a kid when I was testing for continuity, soldering, stripped wires, and performing hundreds of other tasks related to electronics. He was the type of person who had trouble conveying such short sentences or one liners as, “I love you, thanks, and sorry.” He made all seven of his kids as they were growing up work in some capacity or another. Some of us worked on a 300+ acre farm, which he had as a “hobby” while he was employed full time for Mountain Bell Telephone. (How ironic that he spliced

phone lines for 44 years, and his youngest child now performs mobile forensics) I thought for years that all this man knew from life, was how to work. Embedded and tangled into all that labor; he taught me things that carry me into what I do and utterly love now. How do I thank a person who has died, but influenced me so much? The answer I guess is to share with others. Just like the old saying: “It’s not what you know in life, but what you share.”

Last, are my children. At the time I wrote this book, two of you were out in the world living on your own. All of you have given me some great memories over the past 25+ years. I have learned (and continue to learn) about patience, sacrifice, and unconditional love. Thank you for (sometimes) listening to me—and also the few times when you decided not to. Hopefully all of you will remember us riding our bikes, lighting off fireworks, the back yard swimming pool(s), the camping trips that include building our Big Ass Fires (BAFs we called them), road trips to Idaho, and most of all, the laugher. I know you didn’t have a choice in the matter, but thanks anyways for being great children. The three of you will always be my greatest accomplishment in this short life.

Introduction

Introduction–The Multitool Two individuals employed in the military were having domestic issues. Partner A wanted to break up with partner B. Partner B refused to terminate their relationship and began arguing with A. Their argument turn violent and B stabbed A in the neck with a Leatherman multitool. B initially refused to allow A to seek medical treatment, and took images (with his cell phone) while he was bleeding. B informed A that after he dies, he would dismember his body, and dispose of him of various dumpsters. A couple hours later, B drops A off at the hospital. A initially does not inform hospital personnel the correct information on how his injuries occurred, and he slips into a coma. B refuses to provide law enforcement a statement about the incident. Both A and B have the first generation HTC G1 Android phones. They have pattern locks across the screen, and at the time of this investigation, there was no commercially available forensic tool that could bypass this security.

The Sex Offender

He left school at 14 years age. Soon, he was being reported as a runaway and found comfort with others who would “crash” at an abandoned house. He learned about various street drugs and how to steal Honda Civics. For a number of years, he was in and out of juvenile detention for several offenses. As he entered into his adult life, his friends were always younger kids, usually half his age. Many times, the friendships would lead to various games that he had

invented. Most of them were inappropriate. One of the parents of a child he was “friends” with called the police about his behavior. He decides to delete the application he used to communicate with the victim, and also deletes all the incriminating images that he shared. Again, he ends up in jail. This time accused of several sexual offenses with a minor child.

The Last Argument She was married just a few months before her death. Her husband took her life and then his own. Her phone was triaged through a forensic tool commonly used by law enforcement. The initial investigation located two short recordings that documented arguments they had been having. She had recorded them without his knowledge, just days prior to their bodies being discovered. After the phone was triaged, the case agent reviewed the case report (media disk). He called the examiner back a few days later. “I believe there’s another large file on her phone that recorded the events that took place at her death. Can you try to get it to play?” The file had initially been “looked over” and dismissed as a corrupt, unplayable sound file. Per the request of the case agent, the file was viewed with additional scrutiny. Using a hex editor, it was found that the file header and footer were missing, but the case agent may be correct; based on the size of the file, and the time and date of its creation, she probably did record her own death.

The Drug Dealer A missing suspected drug dealer was located, murdered. His lower torso was recovered, buried, and contained inside a duffle bag. His cellular phone had absorbed his human fluids as he had decomposed over a few mouths. Local law enforcement cleaned the device and again connected it to common forensic tools to perform a data extraction. The extraction would start, and then fail. After numerous troubleshooting steps, they still could not gain entry into the device. Although they had cleaned it, the main board was still black from his

bodily fluids. The device was supported by commercial forensic tools for user security bypass, but that was not the problem. They obviously needed a different technique to locate what was needed in their case, and glean insight into who may have communicated with him before his disappearance.

Truth Is Not Pretty These summaries were just some of the small snippets from the author’s experience when it comes to triaging mobile evidence. Each of them came into the laboratory with something missing—answers. In these examples, the author was eventually able to locate what was being requested. Some of the cases were from the author’s own department, and others were from outside agencies where he provided technical assistance. There are times when finding the answer can help add another layer to the story. There are times when the answer helps the public understand a traumatic event with precise clarity. Then there are times when no one seems to give much regards to the truth. A drug dealer? A prostitute? Many in society may not admit that they feel little to no remorse when it comes to specific victims of certain types of crimes having a tragic ending to their life. Locating the truth within an investigation does not necessarily mean that it can be solved. There are times when investigators know exactly who the primary suspect or suspects are. Truth does not necessarily incarcerate someone.

As we hear more horrific events unfold that involve mass causalities, one of the common things we hear being asked at work, dinner parties, and family get-togethers is the why question. People want to know what goes through the mind of a person, and why they acted a certain way. Why did he stab his domestic partner and took images of him while he was bleeding, or why the sex offender wanted to victimize little kids, or why a man must kill his wife and himself, or why one drug dealer kills and dismembers a fellow drug dealer? These investigations, like yours, have a why that must be answered to society. It is incumbent on you to gain enough knowledge to get the

task accomplished. If your job focuses on locating these answers from mobile evidence, this book was created to help you.

Book Layout–The Companion Site Seeking the Truth from Mobile Evidence has been written to allow the reader to see specific steps, program interfaces, techniques, equipment, and overall forensic methods. The author wants the reader to understand the subject materials being conveyed in each chapter. As such, the publisher strives to keep production costs down. This effort has been awarded back to the consumer, and instead of a book costing over hundreds of dollars, it is a third of that cost. Why is this being conveyed to you? As you read several of the chapters, you will encounter instructions directing the reader to images stored on the (included) companion site. There will be a few chapters (Chapters 1, 3, 12, 13, 17, and 29) that do not have references to images found on the companion site. Some of the chapters will also have additional documents such as PDF files that will be contained on the companion site (https://www.elsevier.com/books-and-journals/book- companion/9780128110560). These can assist the reader with supplemental information related to the topic in the chapter they are contained in.

Readers can utilize the (above) link to navigate to the figures, and extra materials on the companion site. On the site, click on the, “Chapter Figures” under Quick Links. The affected chapters are highlighted accordingly. Simply click on the desired chapter to begin the process of downloading a zipped folder for the items listed in the narrative of that chapter. If readers elect to do so, all the materials can be downloaded prior to reading each chapter to allow quicker reference.

Initially, the author was skeptical about the use of the companion site, as it seemed to take the “flow” away from what was trying to be conveyed. But this is obviously not a novel and should be used as a reference guide for your cases. From a learning and direction point of view however, it also certainly added additional value and aided in the overall objective. The printed book has approximately 200 black- and-white images, while the eBook version has the same images in

https://www.elsevier.com/books-and-journals/book-companion/9780128110560
color. Students, private investigators, corporate forensic investigators, prosecutors, and judicial officers can benefit in using this book. The main target audience is law enforcement personnel. The point of view of the author is derived from an active commissioned police officer

(Detective), with over 28 years of experience and hundreds of actual forensic examinations.

Fundamental Concepts Part 1—Chapters 1–12 deal with the investigative (forensic) foundation. Readers will begin with understanding the types of mobile forensic examinations, what causes contamination, and how to properly prevent altering evidence. They continue with the legal process, an understanding of how mobile network and virtual network operators work, and suggestions on search warrant language. The cellular network, subscriber identity module, and device identifications are also explained. Part 1 concludes with how to properly triage mobile evidence that is on and off, the logical examination, troubleshooting, manual examinations, and report writing. At the end of Part 1 the reader should have a good understanding of the core elements needed for basic, mobile evidence investigations.

Intermediate Concepts Part 2—Chapters 13–18 provide the reader with more knowledge related to the physical examination, and the various encoding types located on mobile evidence. These chapters expand on the composition of the NAND and NOR memory. They address date/time stamp epochs and integer formats. How application and MMS data may be missed by forensic tools but decoded manually. Techniques are provided on how to perform advanced validation. By the end of Part 2, readers should have an understanding on how physical encoding will appear, various time stamps and their decoding, manual decoding MMS missed by tools, decoding application data,

and how to conduct and testify on advanced validation.

Advanced Concepts Part 3—The remaining Chapters 19–30 take the reader through advanced techniques that are nondestructive, and destructive. They start by addressing Android and iPhone user enabled security. Readers will understand how to manually decode the gesture pattern and create their own SHA-1 values that they decode with a rainbow table. Several commercial exploit tools are explained that allow the user to locate user enabled passcodes on specific Android and iPhones. They are introduced to the Joint Test Action Group (JTAG) concepts, specialized tools, and specific hardware-based tools that can be used for the JTAG acquisition. This expands into popular JTAG boxes and how to use them. Chapter 21 addresses phone disassembly and focuses on repairing water-damaged phones. The last few chapters cover destructive techniques. Thermal and nonthermal concepts are explained, which include milling and “lap and polishing” techniques. The reader will understand how to perform both types of chip-off processing, as well as how to read the chip after it has been prepared, and steps on how to create a forensic image. Regular expressions are briefly introduced and numerous examples are provided. At the end of the book, the reader is exposed to eMMC reading and the In-System Programming examination.

Summary The goal of this book is to educate readers on various steps they can employ to locate artifacts (off mobile evidence) they may have missed in the past. Years of practical examination experience on violent cases, courtroom testimony, forensic tool experience, as well work at the University of Washington’s Institute of Technology, assisted in the creation of this book. During the judicial process, the author has been referred to as an “expert.” The author has always been uncomfortable with the word expert. This implies that a person has “authoritative knowledge” over _______________________ (you fill in the blank).

Digital forensics, just like mobile phones, changes very rapidly. Just when you think you know something, you don’t. There are several techniques, tools, and methods that the reader will be exposed to within this book. By no means does this equate to expert advice. Imagine a coworker who works with you, whom you approach from time to time, for help. For some of you, you may need to imagine someone working somewhere else, but you respect and admire whoever this person is in your mind. He/she has a couple tidbits of information on occasion that seems to assist you with your digital forensic work. There is no magic in what he/she tells you, and he/she provides suggestions you may have not thought of. Any advice he/she renders seems to complement something that already works well for you. That is how you should think of the author who wrote this book —a friendly coworker who wants to offer suggestions. Your equal who may help you catch the bad guys or assist in locating answers for your employer. He would be offended if someone called him an expert. A nerd maybe, but not an expert.

PART 1 Basic, Fundamental Concepts OUTLINE

Chapter 1. Defining Cell Phone Forensics and Standards Chapter 2. Evidence Contamination and Faraday Methods Chapter 3. The Legal Process—Part 1 Chapter 4. The Legal Process—Part 2 Chapter 5. The Cellular Network Chapter 6. Subscriber Identity Module Chapter 7. Device Identification Chapter 8. Triaging Mobile Evidence Chapter 9. The Logical Examination Chapter 10. Troubleshooting Logical Examinations Chapter 11. Manual Examinations Chapter 12. Report Writing

C H A P T E R 1

Defining Cell Phone Forensics and Standards

Abstract This chapter provides a definition for cell phone forensics in three simple key words. Within this chapter, these are expanded on and provide the reader with a comprehensive understanding of the components involved in this unique forensic field. The logical and physical examination types are also discussed, and the reader is shown visual examples of each. As the chapter continues, it explains the specific standards that need to be followed, with reference to the guidelines on mobile forensics that are provided by the National Institute of Standards and Technology (NIST). Agencies and companies that are tasked with processing digital evidence must at times follow federal, state, and internal policies. There should also be minimum standards that these are built on. Building a standard operating procedure, an internal policy, or a guide should always include aspects from a number of sources such as NIST, any applicable set standard, and a review from any legal representative.

Keywords Cell phone forensics; File system examinations; Logical examinations; Mobile forensics standards; NIST; Physical examinations; Recovering cellular data; Validated data

INFORMATION IN THIS CHAPTER

• Defining cell phone forensics • Recovering • Data • Logical data • File system

• Physical data • Validating • Standards • National Institute of Standards and Training (NIST)

Introduction What is Cell Phone Forensics? Before we begin to answer this question, let us briefly address how the general public has recently begun to learn more about this field. At the time that this book was being written, many people who may have been uninterested in mobile forensics have learned aspects about this practice by reading about how the Federal Bureau of Investigation (FBI) and Apple had conflicting views on how to recover data from a suspected terrorist’s iPhone. An outside entity ultimately assisted in the case and was able to defeat user-enabled security and allow a forensic search to be conducted. There are many moving parts that are involved in that case, and it can be boiled down to the protection of user data weighing heavily in balance with due process. However, the purpose of this book is not to address those issues. During that particular period of unresolved issues between the FBI and Apple, more individuals asked the author’s opinion (about the case) than during any other criminal investigation he had been involved with up to that date. Some begin understanding a few of the elements that are involved with mobile forensics. Because of the nature of the terrorism case, people would actually want to hear more details than normal about this field. They would express valid points from both sides of the argument. The author would normally have “light-hearted” conversations with acquaintances regarding work. Now, they were now bringing up elements that dealt directly into their constitutional rights. Oftentimes the conversation led to answering the question that was posed at the start of this chapter.

Defining Cell Phone Forensics Cell Phone Forensics is the process of recovering cellular-related data through a forensic examination using validated means. To understand this, we must expand on the three key words that have been used in this definition.

Recovering To recover data, we must first actually have an incident in which the need has arisen to obtain the specific artifacts. For law enforcement, this will generally originate from an actual crime that has occurred. In the private sector, this could be a breach of network security or a financial loss. Within the elements of the case itself, there would be a mobile device that contains potential evidence related to the crime or incident. The key element that is necessary to recover potential data is the legal process. The legal process and its requirements are addressed in chapters 3 and 4. Once the legal process is met, the acquisition of the device can take place. In short, the ability to begin “recovering” data is tied to obtaining the legal process.

Data The actual artifacts that are located on mobile devices are categorized as logical and physical. Logical data is easy to understand. Within the target device, it can be viewed through the graphical user interface (GUI). For example, this may be a stored image, text message content, or a phone book contact. Vendors who sell mobile phones often invest in features that complement the user’s ability to use, manage, and interact with logical data. This will include the camera, sending and receiving messages, navigational assistance, and web browsing, to name a few.

Logical data will not require special tools, programs, or training to interpret. It will usually have its own story to tell. This is what most prosecutors will want to introduce to the jury. Fig. 1.1 depicts logical data as commonly viewed through the screen of a flip phone. This is a

(redacted) short message service (SMS) that simply indicates “Hello” as the content. The entire message with the date and time it was sent can logically be viewed by scrolling down within the screen. This message would be stored in a particular encoded fashion within the memory of this device. We will explain encoding in a later chapter, but for now let us understand that this message was created by the user. Without actually knowing it, this same user of the device turned on a series of bytes that in turn were encoded by the operating system (OS). These bytes then displayed on the GUI so that it could be understood by the user. All this was going on inside the phone’s memory with little to no thought of how it all works.

Physical data can be defined as the composition of logical data. These are the “ingredients” that make up what the user may be viewing or may have once seen, as in the case where the data have been deleted. Here is an example. Pretend for a minute that you are a bad guy. You and another bad guy have conspired to murder other individuals. The murder was committed using firearms. The (two) victim’s bodies were to be disposed of in a city landfill. Your coconspirator has a phone number of 12536065884. Your phone number is the same number that was used as the example in the top image in Fig. 1.1—“TO”: 514-5 (redacted). You send a message about this offense to your bad guy friend, but after it is sent, you delete it. Logically no one can see the message when they look in the “Sent” folder of the phone. Physically, however, an examiner could locate the message if certain circumstances were present within the file system. Using the values of the physical encoding, an examiner searches for the bad guy’s number, 2536065884, within the binary. The deleted message is located. Using special programs, the entire message can now be read.

At the bottom of Fig. 1.1 is an example of physical data related to this example. Later, we will explain much more about physical data, types of encoding, interpreting timestamps, and additional elements related to this example.

FIGURE 1.1 Example of logical data: short message service (SMS) sent message “Hello” and physical data example: deleted SMS related to homicide.

There are some things to remember about logical and physical data. Here are two lists that separate some of the main points of both data types.

Logical Data • Data may be limited and generally do not contain deleted artifacts. • It usually requires some form of application program interface or a

specific agent to pull the requested information off the target mobile device.

• Logical data can easily be interpreted, needing no specific training or programs.

• The data is more often used in court or judicial proceedings to illustrate a theory, corroborate the incident or a particular statement, or stand alone as evidence.

• The most commonly requested logical data related to mobile forensics is SMS or multimedia message service (MMS) content, followed by images. There is of course additional logical data increasingly being sought. This will generally be based on the supported device and will include but is not limited to contacts,

call history, chats, videos, web history, bookmarks, Global Positioning System artifacts, and user-installed applications.

• Some of the examples of logical data extractions that can be obtained with both open-source and commercial forensic programs include file system, Android backups, and Advanced Logical.

Physical Data • There are less commercially available tools for physical extractions

than there are for logical extractions. • Examination processing times are generally much longer. • Physical examinations increase the likelihood of recovering deleted

data. • The person performing a physical examination may require

additional training related to the forensic process or the specific program, utility, or hardware being utilized.

• Decoding of some data may require “hand carving” the artifacts using specialized programs and search techniques.

• The physical examination can include advanced nondestructive and destructive techniques to include Joint Test Action Group Boundary Scan or chip-off removal. These types of examinations can require additional specialized training and unique solder techniques and result in high continued costs for necessary equipment. Due to the nature of some physical examinations, examiners must conduct a high number of test examinations on nonevidential devices prior to working on actual cases.

Validating Our last key word in defining Cell Phone Forensics is the process of validation. If we were to place importance on any of the three key words in our definition, validation carries the most weight. It is often the most overlooked part of the forensic process. We will briefly discuss the aspects of validation as it pertains to our definition and expand on this in Chapter 18: Advanced Validation.

Many individuals who have attended mobile forensics training are generally excited about using their specialized equipment or practicing a technique that has been introduced to them. They quickly learn the idiosyncrasies of the program or hardware, pulling incriminating evidence off the phone used in a violent crime. Their supervisor, case agents, or prosecutors are quite pleased with the compelling results.

What may come next are the rigors of the judicial process. They are asked about their validation techniques. This may include a combination of areas to include a program, a utility, or a unique hardware solution. It may simply be the content of an SMS message or if the phone clock reflects the proper time zone, which may show as Coordinated Universal Time on the report created by the commercial forensic tool.

There are generally four ways in which data that is acquired off mobile devices during the forensic acquisition can be validated.

Visual Validation During visual validation, the examiner is simply utilizing the GUI of the device to confirm what the tool is reporting. If we revisit our previous SMS message from our logical data example, utilize a common commercial forensic tool to pull the data, and then compare the results visually on the GUI of the phone, we have conducted a visual validation as pictured at the top of Fig. 1.1.

The process of conducting a Visual Validation can be time consuming. This will be especially true when the case involved data acquired from a smartphone. There will be times when visual confirmation is used in conjunction with another form of validation. Visual validation, should at a minimum, be conducted in nearly every case when it is possible. Later in this book the reader will discover incidents where the phone may be damaged or a destructive technique is required such as removing the memory off the main board. Visual validation may not apply in those circumstances. Fig. 1.2 is an example of visual validation. The left image is of the GUI of the phone, and the right image would be from what a logical

acquisition tool would report.

FIGURE 1.2 Example of visual validation.

Cross Tool Examiners may utilize more than one forensic tool, utility, program, etc., to confirm stored data off a targeted mobile device. Some agencies or private entities may only have one or two forensic tools in their laboratories due to budgetary constraints. There may, however, be a secondary open-source tool that is available to support the target phone. The use of one product to confirm the findings of another is cross tool validation.

Our example in Fig. 1.3 provides validation from the results of one SMS entry using two free utilities: AccessData’s Forensic Tool Kit (FTK) Imager and an open-source tool called BitPim. In this example, we can see that both products are reporting the same type of message (outbox), with the same date, time, and content of the message. Of course, the dates and times need to be manually decoded, which we will discuss in a later chapter. In this example, the content of the message regarding drugs (got poop) is highlighted.