File System Forensics

Comprehensive forensic reference explaining how file systems function and how forensic tools might work on particular file systems File System Forensics delivers comprehensive knowledge of how file systems function and, more importantly, how digital forensic tools might function in relation to specific file systems. It provides a step-by-step approach for file content and metadata recovery to allow the reader to manually recreate and validate results from file system forensic tools. The book includes a supporting website that shares all of the data (i.e. sample file systems) used for demonstration in the text and provides teaching resources such as instructor guides, extra material, and more. Written by a highly qualified associate professor and consultant in the field, File System Forensics includes information on:

• The necessary concepts required to understand file system forensics for anyone with basic computing experience
• File systems specific to Windows, Linux, and macOS, with coverage of FAT, ExFAT, and NTFS
• Advanced topics such as deleted file recovery, fragmented file recovery, searching for particular files, links, checkpoints, snapshots, and RAID
• Issues facing file system forensics today and various issues that might evolve in the field in the coming years

File System Forensics is an essential, up-to-date reference on the subject for graduate and senior undergraduate students in digital forensics, as well as digital forensic analysts and other law enforcement professionals.

List of contents

Preface xvii 
Acknowledgements xxi 
Part I Preliminaries 1 
1 Introduction 3 
1.1 What is Digital Forensics? 4 
1.2 File System Forensics 5 
1.3 Digital Forensic Principles 5 
1.4 Digital Forensic Methodology 7 
1.4.1 Preparation 8 
1.4.2 Localisation/Preservation 8 
1.4.3 Acquisition 8 
1.4.4 Processing 9 
1.4.5 Analysis 9 
1.4.6 Reporting 9 
1.4.7 Quality Assurance 10 
1.4.8 Evidence Return 10 
1.5 About This Book 10 
1.5.1 Who Should Read This Book? 11 
1.6 Book Structure 12 
1.7 Summary 13 
Exercises 13 
Bibliography 14 
2 Linux as a Forensic Platform 17 
2.1 Open-Source Software 17 
2.1.1 Advantages of Open-Source Software 19 
2.1.2 Open Source ¿ Free 20 
2.2 Open-Source Software in Digital Forensics 20 
2.3 What is Linux? 21 
2.3.1 The Anatomy of the Linux OS 22 
2.3.2 Linux Distributions 27 
2.3.3 A (very) Brief History of Linux 28 
2.4 Using Linux 29 
2.4.1 User Accounts 30 
2.4.2 Basic Linux Commands 32 
2.4.2.1 Navigating the File System 32 
2.4.2.2 Getting Help 34 
2.4.2.3 Viewing/Editing Text Files 34 
2.4.2.4 Managing Directories 35 
2.4.2.5 Redirection and Pipes 35 
2.5 Linux as a Forensic Platform 36 
2.5.1 Commands for Digital Forensics 36 
2.5.1.1 Hashing 36 
2.5.1.2 Hex Viewers 38 
2.5.1.3 Archiving/Compression 39 
2.5.1.4 The file Command 40 
2.5.1.5 The strings Command 40 
2.5.1.6 Text Searching with (e)grep 41 
2.6 Summary 42 
Exercises/Discussion Topics 42 
Bibliography 43 
3 Mathematical Preliminaries 45 
3.1 Bits and Bytes 45 
3.2 Number Systems 48 
3.2.1 Notational Conventions 48 
3.2.2 Decimal 48 
3.2.3 Binary 49 
3.2.4 Hexadecimal 50 
3.2.5 Number Conversions 51 
3.2.6 Number Conversion with Bash 51 
3.2.7 Negative Numbers 53 
3.2.8 Floating-Point Numbers 53 
3.3 Representing Text 56 
3.3.1 Ascii 56 
3.3.2 Iso- 8859 57 
3.3.3 Unicode 59 
3.3.4 Utf- 8 60 
3.3.5 Utf- 16 61 
3.4 Representing Time 62 
3.4.1 Unix Time 63 
3.4.2 The Linux date Command 64 
3.5 Endianness and Raw Data 64 
3.6 Summary 66 
Exercises 67 
Bibliography 68 
4 Disks, Partitions and File Systems 69 
4.1 Disk Storage 70 
4.1.1 Traditional Rotational Hard Drives 71 
4.1.1.1 Optical Media 72 
4.1.2 Flash Drives 73 
4.1.3 Solid-State Drives 73 
4.2 Partitions 74 
4.2.1 Creating Partitions/File Systems on Linux 74 
4.2.1.1 Mounting File Systems on Linux 77 
4.2.2 Master Boot Record 78 
4.2.3 GUID Partition Table 80 
4.3 File Systems 83 
4.3.1 File System Concepts 83 
4.3.2 Comparison of File Systems 86 
4.4 Acquisition of File System Data 88 
4.4.1 Logical vs Physical Acquisition 88 
4.4.2 Acquisition Under Linux 88 
4.4.2.1 The dd Family 89 
4.4.2.2 Expert Witness Format (EWF) 90 
4.4.2.3 guymager 91 
4.5 Analysis of File Systems 92 
4.5.1 The Sleuth Kit 92 
4.5.1.1 Determine the Partition Layout 93 
4.5.1.2 Determine the File System Type 93 
4.5.1.3 List the Files 94 
4.5.1.4 Recover File Metadata 95 
4.5.1.5 Recover File Content 95 
4.5.1.6 Other TSK Commands 95 
4.5.2 Data Carving 96 
4.6 Summary 97 
Exercises 97 
Bibliography 98 
Part II Windows File Systems 99 
5 The FAT File System 101 
5.1 On-Disk Structures 101 
5.1.1 Layout 102 
5.1.2 Volume Boot Record 102 
5.1.3 File System Information (FSINFO) 102 
5.1.4 File Allocation Table 104 
5.1.5 Directory Entries 105 
5.1.6 FAT Date and Time 108 
5.1.7 Mapping Clusters to Sectors 109 
5.2 Analysis of FAT 32 109 
5.2.1 Creating FAT32 File Systems 109 
5.2.2 Supplied FAT32 Image Files 110 
5.2.3 FAT32 Manual Analysis 110 
5.2.3.1 Process the VBR 111 
5.2.3.2 Process the Root Directory 112 
5.2.3.3 Process Sub-directories 113 
5.2.3.4 Recover Metadata/Content 113 
5.3 FAT32 Advanced Analysis 115 
5.3.1 Deleted Files 116 
5.3.2 The Volume Label 117 
5.4 Summary 117 
Exercises 118 
Bibliography 118 
6 The ExFAT File System 121 
6.1 On-Disk Structures 121 
6.1.1 Volume Boot Record 122 
6.1.2 File Allocation Table 123 
6.1.3 Directory Entries 125 
6.1.3.1 Allocation Bitmap (Type: 0x81) 127 
6.1.3.2 Up-Case Table (Type: 0x82) 128 
6.1.3.3 Volume Label (Type: 0x83) 128 
6.1.3.4 File (Type: 0x85) 129 
6.1.3.5 Volume GUID (Type: 0xA0) 130 
6.1.3.6 Stream Extension (Type: 0xC0) 130 
6.1.3.7 Filename Extension 131 
6.1.3.8 Other Directory Entries 132 
6.2 Analysis of ExFAT 132 
6.2.1 Creating ExFAT File Systems 132 
6.2.2 Supplied ExFAT Image Files 132 
6.2.3 ExFAT Manual Analysis 132 
6.2.3.1 Step 1: Process the VBR 133 
6.2.3.2 Step 2: Process the Root Directory 133 
6.2.3.3 Step 3: Process Subdirectories 136 
6.2.3.4 Step 4: Recover Metadata 137 
6.2.3.5 Step 5: Recover Content 137 
6.3 ExFAT Advanced Analysis 139 
6.3.1 Long File Names 139 
6.3.2 Deleted Files 140 
6.3.3 Fragmented Files and Large Directories 141 
6.4 Summary 142 
Exercises 143 
Bibliography 143 
7 The NTFS File System 145 
7.1 On-Disk Structures 146 
7.1.1 $Boot 146 
7.1.2 Indexes 147 
7.1.3 Fixup Arrays 149 
7.1.4 Time in NTFS 150 
7.1.5 Master File Table 151 
7.1.6 MFT Record Structure 152 
7.1.6.1 MFT Record Header 152 
7.1.6.2 Browsing Attributes 155 
7.1.6.3 $STANDARD_INFORMATION (0x10) 155 
7.1.6.4 $ATTRIBUTE_LIST (0x20) 156 
7.1.6.5 $FILENAME (0x30) 156 
7.1.6.6 $OBJECT_ID (0x40) 157 
7.1.6.7 $SECURITY_DESCRIPTOR (0x50) 159 
7.1.6.8 $VOLUME_NAME (0x60) 162 
7.1.6.9 $VOLUME_INFORMATION (0x70) 162 
7.1.6.10 $DATA (0x80) 163 
7.1.6.11 $INDEX_ROOT (0x90) 163 
7.1.6.12 $INDEX_ALLOCATION (0xA0) 165 
7.1.6.13 $BITMAP (0xB0) 165 
7.1.6.14 $REPARSE_POINT (0xC0) 166 
7.1.6.15 $EA_INFORMATION (0xD0) and $EA (0xE0) 167 
7.2 Analysis of NTFS 167 
7.2.1 Creating NTFS File Systems 168 
7.2.2 Supplied NTFS Image Files 168 
7.2.3 NTFS Manual Analysis 168 
7.2.3.1 Process $Boot 169 
7.2.3.2 Recover $MFT 171 
7.2.3.3 Process Directories 173 
7.2.3.4 Recover File Metadata 177 
7.2.3.5 Recover File Content 182 
7.3 NTFS Advanced Analysis 185 
7.3.1 Further File System Information 185 
7.3.2 Deleted Files 186 
7.3.3 Fragmented Files 187 
7.3.4 Alternate Data Streams 190 
7.3.5 Large MFT Records 191 
7.4 Summary 194 
Exercises 194 
Bibliography 195 
Part III Linux File Systems 197 
8 The EXT2 File System 199 
8.1 On-Disk Structures 200 
8.1.1 The Superblock 201 
8.1.2 The Block Group Descriptor Table 204 
8.1.3 The Inode Table 205 
8.1.3.1 Mode/Permissions 207 
8.1.3.2 Inode Flags 208 
8.1.3.3 Block Pointers 208 
8.1.4 The Data and Inode Bitmaps 209 
8.1.5 Locating an Inode 209 
8.2 Analysis of ext 2 210 
8.2.1 Creating ext2 File Systems 210 
8.2.2 Supplied ext2 Image Files 210 
8.2.3 Ext2 Manual Analysis 211 
8.2.3.1 Process the Superblock 211 
8.2.3.2 Map the Block Groups 213 
8.2.3.3 Process Root Directory Inode 216 
8.2.3.4 Process the Root Directory 217 
8.2.3.5 Process Directories 219 
8.2.3.6 Process Files 219 
8.3 Ext2 Advanced Analysis 222 
8.3.1 Fragmented Files 222 
8.3.2 Links 223 
8.3.3 Deleted Files 225 
8.4 Summary 226 
Exercises 226 
Bibliography 227 
9 The EXT3/EXT4 File Systems 229 
9.1 Supplied Image Files 229 
9.2 The ext3 File System 229 
9.2.1 The Ext Journal 230 
9.2.2 HTree Directory Indexing 237 
9.3 The Ext4 File System 241 
9.3.1 Large Inodes 241 
9.3.1.1 Timestamps 241 
9.3.2 Ext4 Data Storage 244 
9.3.2.1 Extent-Based Storage 244 
9.3.2.2 Inline Storage 248 
9.3.2.3 Symbolic Links 248 
9.3.3 File Deletion in Ext 4 249 
9.3.4 Extended Attributes 252 
9.3.5 Ext4 Block Group Descriptors 255 
9.3.6 Flexible Block Groups 255 
9.4 Summary 258 
Exercises 259 
Bibliography 260 
10 The XFS File System 263 
10.1 On-Disk Structures 264 
10.1.1 Allocation Groups 264 
10.1.2 Addressing 266 
10.1.2.1 Inode Addressing 266 
10.1.3 XFS B+ Trees 267 
10.1.4 The Superblock 268 
10.1.4.1 Locating Superblocks 268 
10.1.5 XFS Signatures 271 
10.1.6 XFS Inodes 271 
10.1.7 Directories 273 
10.1.8 Extents 274 
10.1.9 Time in XFS 275 
10.2 Analysis of XFS 275 
10.2.1 Creating XFS File Systems 275 
10.2.2 Supplied XFS Image Files 275 
10.2.3 XFS Manual Analysis 276 
10.2.3.1 Process the Superblock 276 
10.2.3.2 Locate the Root Directory 277 
10.2.3.3 Process the Root Directory 279 
10.2.3.4 Process the Subdirectories 281 
10.2.3.5 Recover File Content/Metadata 281 
10.3 XFS Advanced Analysis 282 
10.3.1 AG Free Space Management 283 
10.3.1.1 AG Free List 285 
10.3.2 AG Inode Management 286 
10.3.3 Deleted Files 289 
10.3.4 Extended Attributes 290 
10.3.5 Links 291 
10.3.6 The XFS Journal 292 
10.4 Summary 300 
Exercises 301 
Bibliography 301 
11 The Btrfs File System 303 
11.1 On-Disk Structures 304 
11.1.1 The Superblock 305 
11.1.2 Btrfs Trees 305 
11.1.3 Btrfs Tree Structure 307 
11.1.3.1 Node Header Structure 307 
11.1.3.2 Internal Node Structure 309 
11.1.4 Btrfs Keys 309 
11.1.5 Btrfs Items 310 
11.1.6 Time in Btrfs 315 
11.1.7 Logical and Physical Addressing 315 
11.2 Analysis of Btrfs 317 
11.2.1 Creating Btrfs File Systems 317 
11.2.2 Supplied Btrfs Image Files 318 
11.2.3 Btrfs Analysis Methodology 318 
11.2.4 Manual Analysis of a Single Device File System 320 
11.2.4.1 Process the Superblock 320 
11.2.4.2 Process the CHUNK_ARRAY 321 
11.2.4.3 Locate the CHUNK_TREE 322 
11.2.4.4 Process the CHUNK_TREE 323 
11.2.4.5 Locate the Root Tree 326 
11.2.4.6 Locate the FS_TREE 327 
11.2.4.7 Processing the FS_TREE 328 
11.2.4.8 Process Directories 329 
11.2.4.9 Recovering Metadata 335 
11.2.4.10 Recovering File Contents 336 
11.3 Btrfs Advanced Analysis 338 
11.3.1 File Deletion 338 
11.3.2 Analysis of Internal Nodes 342 
11.3.3 Multiple Device Configuration 343 
11.3.4 Subvolumes and Snapshots 346 
11.4 Summary 350 
Exercises 350 
Bibliography 351 
Part IV Apple File Systems 353 
12 The HFS+ File System 355 
12.1 On-Disk Structures 355 
12.1.1 Forks 357 
12.1.2 Time in HFS+ 357 
12.1.3 Volume Header 358 
12.1.4 B-Trees 358 
12.1.5 Catalog File 362 
12.1.6 HFS+ Permissions 363 
12.1.7 Text Encoding 365 
12.1.8 Extents Overflow File 365 
12.1.9 Allocation File 366 
12.1.10 HFS+ Journal 367 
12.2 Analysis of HFS+ 369 
12.2.1 Creating HFS+ File Systems 369 
12.2.2 Supplied HFS+ Image Files 370 
12.2.3 HFS+ Manual Analysis 370 
12.2.3.1 Process the Volume Header 370 
12.2.3.2 Locate the Catalog File 371 
12.2.3.3 Process the Catalog B-Tree 373 
12.2.3.4 Gather Metadata 377 
12.2.3.5 Recover File Content 377 
12.3 HFS+ Advanced Analysis 380 
12.3.1 Deleted Files 380 
12.3.2 Index Nodes 381 
12.3.3 Fragmented Files 383 
12.3.4 Links 387 
12.4 Summary 390 
Exercises 391 
Bibliography 391 
13 The APFS File System 393 
13.1 On-Disk Structures 394 
13.1.1 Time in APFS 394 
13.1.2 Objects 394 
13.1.3 B-Trees 396 
13.1.4 Containers and Volumes 399 
13.1.5 Container Superblock 400 
13.1.6 Volume Superblock 402 
13.1.7 Object Maps 404 
13.1.8 File-Related Structures 405 
13.1.8.1 File System Keys 406 
13.1.8.2 Inode 407 
13.1.8.3 Directory Record 408 
13.1.8.4 Extent 410 
13.1.9 Checkpoints 410 
13.1.10 Other APFS Structures 412 
13.2 Analysis of APFS 412 
13.2.1 Creating APFS File Systems 412 
13.2.2 Supplied APFS Image Files 413 
13.2.3 APFS Manual Analysis 413 
13.2.3.1 Process the Container Superblock 414 
13.2.3.2 Process the Container Object Map 415 
13.2.3.3 Process the Volume Superblock 418 
13.2.3.4 Process the Volume Object Map 418 
13.2.3.5 Process the File System Tree 419 
13.3 APFS Advanced Analysis 425 
13.3.1 Deleted Files 425 
13.3.2 Checkpoint Recovery 426 
13.3.3 Multi-Level B-Trees 427 
13.3.4 Multiple Volumes 429 
13.3.5 Extended Attributes 430 
13.3.6 Links 431 
13.4 Summary 433 
Exercises 433 
Bibliography 434 
Part V The Future 435 
14 Future Challenges in Digital Forensics 437 
14.1 Challenges in Digital Forensics 437 
14.1.1 Data Volume 438 
14.1.2 Multi-Source Correlation 439 
14.1.3 New File Systems 440 
14.1.4 Encryption 440 
14.1.5 Cloud Storage 441 
14.1.6 Lack of Resources 441 
14.1.6.1 Human Resources 441 
14.1.6.2 Software Resources 442 
14.1.6.3 Hardware Resources 442 
14.1.7 Tool Validation/Datasets 443 
14.1.8 Lack of Standardisation 444 
14.1.9 Legal/Scientific Challenges 444 
14.1.10 Presentation of Evidence 445 
14.1.11 Human Error/Bias 446 
14.2 Where Do We Go from Here? 447 
14.2.1 Training/Education 448 
14.2.2 Free Open-Source Software (FOSS) 448 
14.2.3 Triage 449 
14.2.4 Artificial Intelligence (AI) 449 
14.2.5 Live Data Forensics 450 
14.2.6 Legal Solutions 451 
14.2.7 Data Set Development/Tool Testing 452 
14.2.8 Standardisation 452 
14.2.9 Information Sharing 453 
14.2.10 Virtualisation 453 
14.3 Summary 454 
Bibliography 454 
Index 457

Product details

• Authors: Fergus Toolan, Fergus (Norwegian Police University Colleg Toolan, Toolan Fergus
• Publisher: Wiley, John and Sons Ltd
• Languages: English
• Product format: Hardback
• Released: 14.03.2025
• EAN: 9781394289790
• ISBN: 978-1-394-28979-0
• No. of pages: 496
• Subjects: Natural sciences, medicine, IT, technology > IT, data processing > IT; computer science, Forensic Science, COMPUTERS / Computer Architecture, Computer architecture and logic design, COMPUTERS / Forensics