From Shell to Signal: Introducing a Linux DFIR Series

Linux is the backbone of modern computing infrastructure. It powers everything from cloud platforms and enterprise servers to embedded systems and containerized applications. Despite its ubiquity, Linux often remains underrepresented in digital forensics and incident response (DFIR) training and tooling, especially when compared to its Windows counterpart. This blog series aims to bridge that gap.

Over the coming posts, we'll build a practical, technically focused framework for Linux DFI, with a particular emphasis on Amazon Linux 2 and Amazon Linux 2023 - two distributions widely used across AWS environments. These systems are optimized for the cloud, but that optimization introduces unique challenges during investigations. From transient disk volumes to XFS file systems, cloud logging integrations to short-lived processes, the nature of forensic analysis in this environment is fundamentally different from traditional endpoints.

This series is built for practitioners facing that reality.

Why This Series?

Cloud platforms have transformed how we deploy, monitor, and secure infrastructure. However, many DFIR techniques haven't kept pace. When an EC2 instance exhibits suspicious behavior, responders often lack persistent access, historical visibility, or standard forensic tooling. Investigations can't rely on snapshots made weeks ago or hope that traditional log paths exist. What's needed is a new approach, one that understands how ephemeral infrastructure works and adapts DFIR techniques accordingly.

This series is intended for analysts, engineers, and security professionals who need to respond to incidents on Linux systems deployed in real-world environments. Whether you're triaging a misconfigured server, investigating suspicious behavior, or building detection coverage from the ground up, this content is designed to help you make sense of the noise and extract signal.

Where We're Starting

We'll begin with core concepts that are foundational to any investigation:

• Understanding the Linux operating system architecture

• Exploring the role of the kernel, init systems, and key directories

• Examining modern file systems like XFS and their metadata structures

• Identifying native logs in Amazon Linux and methods to extract valuable information

  
  

These initial posts will serve both as a refresher for experienced users and as onboarding for those looking to build DFIR skills from the ground up. The emphasis will be on clarity, practical use cases, and preparing you to work effectively in AWS-hosted environments.

Where We're Going

Once the groundwork is in place, we'll progressively delve into more advanced forensic techniques and response workflows, including:

• File recovery and timeline reconstruction on XFS

• Investigating memory-resident malware and acquiring volatile data

• Analyzing privilege escalation and persistence techniques

• Interpreting audit logs, journaling systems, and tamper-resistant logging

• Detecting anti-forensics and post-exploitation activity

• And so on...

Each post will build on prior topics while introducing tools, methods, and investigation strategies that reflect real-world challenges. The goal isn't to cover every tool; it's to develop a consistent, repeatable mindset for responding to Linux-based incidents effectively.

Acknowledging The True Experts

It's important to recognize the pioneers who have laid the groundwork in this field. Hal Pomeranz, a renowned expert in Linux forensics, has significantly contributed to the community through his research, tools, and training. His work has been instrumental in shaping modern approaches to Linux DFIR. 

Additionally, the SANS Institute's FOR577: Linux Incident Response and Threat Hunting course offers comprehensive training that equips professionals with the skills needed to identify, analyze, and respond to attacks on Linux platforms. The course emphasizes hands-on incident response and threat hunting tactics, providing practical experience through extensive labs.

Both Hal Pomeranz's teachings and the FOR577 course have been invaluable in advancing the practice of Linux forensics and incident response. Their work has set the standard for rigorous, real-world training in this space. This blog series is not intended to compete with or replicate those efforts. Instead, it’s a personal initiative—a way for me to document what I’m learning, develop my own research methods, and deepen my understanding through hands-on exploration. If anything, this series builds on the foundation they’ve helped create and reflects my attempt to grow within that ecosystem.

Who This Is For

This series is written for those who work with Linux in security-sensitive environments, whether you're on a blue team, red team, cloud platform team, or something in between. You don't need to be an expert in forensics to follow along. A working knowledge of the Linux command line and a desire to understand what systems are really doing beneath the surface will take you far. Along the way, we'll include reference material, scripts, walkthroughs, and lab-ready examples to make it easier to apply what you learn.

Why I'm Writing This

Forensic knowledge compounds. The more you investigate, the more you recognize patterns, artifacts, and subtle signs of compromise. But for that to happen, you need structured practice. You need to understand not only what is happening on a system, but why it's happening—and how you can prove it.

Writing this series is an opportunity to document, refine, and share those insights. The goal is to create something technically grounded, logically structured, and practically useful - not just another checklist, but a forensic field guide for working with Linux in the cloud.

What's Next

The first post will focus on how Linux is architected—from the kernel to user space—and what that means for forensic investigations. It will lay the foundation for understanding where evidence lives, how it's generated, and how it can be interpreted.

From there, we'll move deeper into the filesystem, log analysis, memory collection, and response automation, one layer at a time.

If you're looking to build a stronger foundation in Linux forensics or expand your response capabilities in AWS environments, this series is for you.

Let's get started.

Thanks for visiting,

 – TracerTick

Disclaimer: All views, thoughts, and opinions expressed on this blog are my own and do not represent the views of my employer or any affiliated organizations. The content here is intended for educational and informational purposes only.