15.2 Digital Forensics Principles and Techniques

Digital forensics is all about uncovering digital evidence to solve crimes. It's like being a detective, but instead of searching for physical clues, you're digging through computers and phones to find hidden data.

In this part, we'll learn how to properly collect and analyze digital evidence. We'll cover techniques for preserving data integrity, recovering deleted files, and examining everything from computer memory to mobile devices.

Digital Evidence Acquisition

Understanding Digital Evidence and Forensic Imaging

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Top images from around the web for Understanding Digital Evidence and Forensic Imaging

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  basic forensics imaging kit | Asus eeepc (battery life 5 hou… | Flickr View original

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  disk imaging via tableau write blocker | Flickr - Photo Sharing! View original

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  tableau usb write blocker | Showing some of the data deliver… | Flickr View original

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• Digital evidence encompasses electronically stored information used in legal proceedings
• Digital evidence includes data from computers, smartphones, and other digital devices
• Forensic imaging creates bit-by-bit copies of digital storage media
• Forensic imaging preserves original evidence integrity for analysis
• Write blockers prevent accidental modification of original data during imaging
• Write blockers function by intercepting write commands to the storage device

Ensuring Evidence Integrity

• Hashing generates unique digital fingerprints for evidence verification
• Hashing algorithms (MD5, SHA-1, SHA-256) produce fixed-length output strings
• Hash values confirm data integrity throughout the investigation process
• Chain of custody documents evidence handling from collection to presentation
• Chain of custody includes details on who, what, when, where, and why of evidence handling
• Proper chain of custody ensures evidence admissibility in court proceedings

Data Types and Analysis

Volatile vs Non-volatile Data

• Volatile data exists temporarily in computer memory (RAM)
• Volatile data disappears when power is removed from the system
• Volatile data includes running processes, network connections, and open files
• Non-volatile data persists after power loss (hard drives, SSDs, USB drives)
• Non-volatile data includes file systems, user files, and system logs
• Investigators prioritize volatile data collection before system shutdown

Advanced Data Recovery Techniques

• File carving recovers deleted or partially overwritten files from unallocated space
• File carving uses file signatures and headers to identify and reconstruct data
• Metadata analysis examines file attributes (creation date, modification time, file permissions)
• Metadata provides crucial information about file history and user interactions
• Timeline analysis reconstructs chronological sequence of events on a system
• Timeline analysis correlates data from various sources (file system, logs, metadata)

Specialized Forensics

Memory and Network Forensics

• Memory forensics analyzes computer RAM contents for evidence
• Memory forensics captures running processes, malware, and encryption keys
• Memory forensics tools (Volatility, Rekall) extract and analyze RAM dumps
• Network forensics examines traffic and logs for suspicious activities
• Network forensics investigates intrusions, data exfiltration, and communication patterns
• Network forensics tools (Wireshark, Snort) capture and analyze network packets

Mobile Device Forensics

• Mobile device forensics extracts data from smartphones and tablets
• Mobile forensics recovers call logs, messages, location data, and app information
• Mobile forensics tools (Cellebrite, XRY) bypass device locks and extract data
• Mobile forensics addresses challenges of diverse operating systems and encryption
• Mobile forensics examines cloud-based data associated with mobile devices
• Mobile forensics considers legal and privacy implications of personal device analysis