Basic Digital Forensic Techniques
Acquire fundamental skills in collecting and preserving digital evidence during a security incident for analysis.
Basic Digital Forensic Techniques is a free Production Debugging & Incident Response Playbook lesson on CoddyKit — lesson 2 of 4. You can read the complete lesson below for free — then practise it hands-on in the browser with a built-in code editor and a 24/7 AI tutor. It is part of the Production Debugging & Incident Response Playbook learning path, one of 4 lessons in the course, and your progress syncs across the web and the CoddyKit app.
What is Digital Forensics?
Welcome to Basic Digital Forensic Techniques! In this lesson, we'll learn how to properly collect and preserve digital evidence during a security incident.
Digital forensics is the process of identifying, preserving, recovering, analyzing, and presenting facts about digital evidence. It's crucial for understanding breaches and for potential legal action.
The Forensic Process Overview
A typical digital forensic investigation follows several key stages:
- Identification: Recognizing a potential incident.
- Preservation: Protecting potential evidence from alteration.
- Collection: Acquiring the evidence.
- Analysis: Examining the collected data.
- Reporting: Documenting findings.
This lesson focuses on the crucial steps of Preservation and Collection.
Principle of Immutability
The golden rule in digital forensics is immutability: never alter the original evidence. Any change, no matter how small, can compromise the integrity and admissibility of the evidence.
Always work on copies of the data. This means creating bit-for-bit duplicates of storage devices and capturing volatile data without modifying the live system more than absolutely necessary.
Capturing Volatile Data First
Volatile data is information that exists only while a system is running and is lost when the system is powered off or rebooted. Examples include:
- System memory (RAM)
- Running processes
- Network connections and open ports
- Logged-on users
This data must be collected first, as it's highly perishable. Tools are used to extract this information from the live system.
Identifying Volatile Data (Example)
While we won't run code directly, understanding common commands helps identify volatile data:
netstat -an: Shows active network connections.ps aux: Lists running processes.who: Displays logged-in users.ipconfig(Windows) /ifconfig(Linux): Shows network interface configuration.
These commands provide a snapshot of the system's current state.
Imaging Non-Volatile Data
Non-volatile data persists even after a system is powered off. This primarily refers to data stored on hard drives, SSDs, USB drives, etc.
To preserve this evidence, a forensic image (a bit-for-bit copy) of the entire storage device is created. This image includes not just active files, but also deleted files, unallocated space, and file system metadata.
Verifying Evidence Integrity (Hashing)
After collecting any digital evidence (volatile or non-volatile), its integrity must be verified. This is done using cryptographic hashing.
A hash function generates a unique, fixed-size string (a 'fingerprint') from a block of data. If even a single bit changes in the original data, the hash value will be completely different.
You calculate the hash of the original evidence and its copy. If they match, you've proven the copy is identical to the original and hasn't been tampered with.
The Chain of Custody
Maintaining a chain of custody is vital for ensuring evidence is admissible in legal proceedings. It's a detailed, chronological record of who has had access to the evidence, when, and for what purpose.
Every transfer, examination, or storage event related to the evidence must be documented precisely. This proves the evidence has been protected from unauthorized access or alteration.
Practical Collection Best Practices
When collecting digital evidence:
- Isolate the system: Disconnect from networks to prevent further compromise or data loss.
- Document everything: Take photos, notes, and log all actions.
- Use write-blockers: Hardware or software tools that prevent any writes to the original evidence drive.
- Prioritize: Collect volatile data before non-volatile.
- Verify: Always use hashing to ensure integrity of copies.
Evidence Handling Check
You've just learned about critical steps in digital evidence collection. Let's test your understanding.
Forensic Fundamentals Recap
Great job! In this lesson, we covered the fundamental techniques for collecting and preserving digital evidence. You learned about:
- The importance of immutability and working on copies.
- Prioritizing volatile data collection.
- Creating forensic images of non-volatile data.
- Using hashing to verify evidence integrity.
- Maintaining a strict chain of custody.
These techniques are essential for any effective incident response and investigation.
Frequently asked questions
Is the “Basic Digital Forensic Techniques” lesson free?
Yes — the full text of “Basic Digital Forensic Techniques” is free to read here on the web, and the Production Debugging & Incident Response Playbook course includes 4 lessons in total. To practise it interactively (a built-in code editor and a 24/7 AI tutor) and unlock the rest of the Production Debugging & Incident Response Playbook course, upgrade to CoddyKit PRO.
What will I learn in “Basic Digital Forensic Techniques”?
Acquire fundamental skills in collecting and preserving digital evidence during a security incident for analysis. You practise Production Debugging & Incident Response Playbook with hands-on code you run directly in the browser, and a 24/7 AI tutor answers your questions as you work through the lesson.
Do I need any experience to start Production Debugging & Incident Response Playbook?
No prior experience is required. Production Debugging & Incident Response Playbook on CoddyKit is structured for beginners through advanced learners; this is — lesson 2 of 4, so you can start here or from the beginning and move at your own pace.
How long does the “Basic Digital Forensic Techniques” lesson take?
Most CoddyKit lessons take about 5–10 minutes. Each one is bite-sized and interactive, so you make steady progress and pick up exactly where you left off across the web and the app.
Can I write and run code in this Production Debugging & Incident Response Playbook lesson?
Yes. Every Production Debugging & Incident Response Playbook lesson includes a built-in code editor, so you write and run real code right in your browser and get instant AI feedback — no local setup required.
All lessons in this course
- Recognizing Security Breaches and Indicators
- Basic Digital Forensic Techniques
- Containment and Eradication Strategies
- Evidence Preservation and Chain of Custody