File System Structures and Artifacts

Lesson 12/47 | Study Time: 20 Min

Course: Computer and Cyber Forensics Professional – Course

File system structures and artifacts form the core of computer and cyber forensics, revealing how data is organized, accessed, and manipulated on storage devices to uncover hidden evidence like deleted files or user timelines. Investigators parse these structures to recover artifacts from metadata, slack space, and journals, turning raw disk sectors into investigative gold.

Core File System Components

Every file system follows a layered architecture, from boot sectors to data blocks, each hiding recoverable clues.

1. Boot Sector/Superblock: Initial sector with file system type, cluster size, and volume details—altered boots signal tampering.

2. Partition Table: Maps divisions (MBR/GPT); lost tables recoverable via tools like TestDisk.

3. Allocation Structures: Track used/free space—e.g., FAT chains or NTFS bitmaps expose orphans.

4. Metadata Zones: Inodes (Linux) or MFT (Windows) hold file attributes, timestamps (MACB: Modified, Accessed, Changed, Born).

Understanding hierarchy—root directories branching to leaves, reveals nesting for hidden data.

Note: These components manage allocation and metadata, where forensics thrives on inconsistencies or remnants.

Key File Systems and Their Structures

Common systems vary in complexity, each with unique forensic hotspots.

Note: Windows/Linux/macOS dominate enterprises; parse accordingly for cross-platform probes.

Critical Artifacts for Timelines and Recovery

Artifacts are the "digital fingerprints" in metadata and waste spaces.

Note: MACB timestamps correlate across files; anomalies like future dates flag manipulation.

1. Timestamps: $Standard_Information (SI) vs $File_Name (FN) in NTFS—discrepancies indicate timestomping.

2. Slack Space: End-of-cluster remnants from prior files; holds partial data for carving.

3. Unallocated Space: Freed clusters with deleted file headers—prime for recovery.

4. Volume Shadow Copies (VSCs): Windows backups preserving historical versions against overwrites.

5. Prefetch/Thumbs.db: Execution caches and previews linking user actions.

Carve by signatures (e.g., JPEG FF D8) in unallocated areas.

Analysis Techniques and Tools

Parse structures methodically to extract and correlate.

Note: Work on images only—tools automate but verify manually.

1. Timeline Generation: Super timelines merging MACB across all files via fls/plaso.

2. File Carving: Scalpel/Foremost recover sans metadata using headers/footers.

3. Metadata Parsing: Analyze MFT with analyzeMFT.py; spot alternate data streams (ADS).

4. Anti-Forensics Detection: Mismatched hashes, zeroed slack, or rapid timestamp changes.

Workflow: Mount read-only → Catalog → Keyword search → Timeline → Report.

Practical Implications in Investigations

In a breach, NTFS $LogFile reconstructs lateral movement; ext4 journals show cron jobs. SSD TRIM erases slack faster—image live systems first. Cross-drive analysis links USB artifacts across endpoints.

Challenges like encryption (EFS) require key recovery from RAM. By 2025, tools like Autopsy integrate AI for anomaly spotting, but structural knowledge grounds interpretations.

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Alexander Cruise

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Class Sessions

1- Evolution of Digital Crime and Cyber Forensics 2- Key Terminology and Scope 3- Digital Evidence Lifecycle and Forensic Principles 4- Legal, Regulatory, and Standards Context 5- Roles and Career Paths in Computer and Cyber Forensics 6- Structured Digital Investigation Methodologies 7- Scoping and Planning an Investigation 8- Evidence Sources in Enterprise Environments 9- Documentation, Case Notes, and Evidence Tracking 10- Working with Multidisciplinary Teams 11- Computer and Storage Architecture for Investigators 12- File System Structures and Artifacts 13- File and Artifact Recovery 14- Common User-Activity Artifacts 15- Principles of Forensically Sound Acquisition 16- Acquisition Strategies 17- Volatile vs Non-Volatile Data Acquisition 18- Handling Encrypted and Locked Systems 19- Evidence Handling, Transport, and Storage 20- Windows Forensics Essentials 21- Linux and Unix-Like System Forensics 22- macOS and Modern Desktop Environments 23- Memory Forensics Concepts 24- Timeline Construction Using OS and Memory Artifacts 25- Network Forensics Fundamentals 26- Enterprise Logging and Telemetry 27- Cloud Forensics (IaaS, PaaS, SaaS) 28- Email and Messaging Investigations 29- Timeline Building from Heterogeneous Logs 30- Modern Malware and Ransomware Landscape 31- Malware Forensics Concepts 32- Host-Level Artifacts of Compromise 33- Ransomware Incident Artifacts 34- Dark Web and Anonymous Network Forensics 35- Common Anti-Forensics Techniques 36- Detection of Anti-Forensics 37- Countering Anti-Forensics 38- Resilient Evidence Collection Strategies 39- Incident Response Frameworks and Phases 40- Forensics-Driven Incident Response 41- Threat Hunting Linked with Forensics 42- Post-Incident Activities 43- Forensic Report Structure 44- Writing for Multiple Audiences 45- Presenting and Defending Findings 46- Ethics, Confidentiality, and Professional Conduct 47- Continuous Learning and Certification Pathways