Linux Endpoint Forensics with GRR Rapid Response

Introduction

GRR Rapid Response is an incident response framework focused on remote live forensics. It allows security professionals to perform detailed investigations on multiple endpoints from a central server. This advanced-level lab will guide you through setting up and using GRR Rapid Response to conduct endpoint forensics on Linux systems, covering installation, configuration, remote data collection, and analysis.

Pre-requisites

• Advanced knowledge of Linux operating systems and command-line interface
• Understanding of forensic principles and techniques
• Familiarity with network and system security concepts
• Basic knowledge of scripting and regular expressions

Lab Set-up and Tools

• A computer running a Linux distribution (e.g., Ubuntu)
• GRR Rapid Response installed
• Multiple Linux endpoints for testing (virtual machines recommended)
• Internet connection for downloading necessary packages

Installing GRR Rapid Response

1. Install dependencies:

   sudo apt update
   sudo apt install python3 python3-pip
   sudo pip3 install virtualenv

2. Clone the GRR repository:

   git clone https://github.com/google/grr.git
   cd grr

3. Set up a virtual environment:

   virtualenv venv
   source venv/bin/activate

4. Install GRR:

   pip install -e .

5. Initialize the GRR server:

   grr_config_updater initialize

Exercises

Exercise 1: Setting Up GRR Server

Objective: Install and configure the GRR server for endpoint management.

1. Configure the GRR server settings:

   grr_config_updater set_var --section=Server.server --varname="AdminUI.url" --value="http://localhost:8000"
2. Start the GRR server:

   grr_server --start
3. Access the GRR web interface at http://localhost:8000 and log in with the default credentials.

Expected Output: GRR server running and accessible via the web interface.

Exercise 2: Deploying GRR Agents on Endpoints

Objective: Install and configure GRR agents on Linux endpoints for remote forensic capabilities.

1. Generate the GRR client installer:

   grr_client_build build --platform linux
2. Transfer the installer to the Linux endpoint.
3. Install the GRR agent on the endpoint:

   sudo dpkg -i grr-client_*.deb
4. Verify that the endpoint appears in the GRR web interface.

Expected Output: GRR agents installed and communicating with the GRR server.

Exercise 3: Performing Live Forensics

Objective: Use GRR to collect live forensic data from a remote endpoint.

1. In the GRR web interface, select an endpoint and navigate to "Flows" > "Launch New Flow".
2. Choose "File Finder" and configure it to collect specific files (e.g., /var/log/auth.log).
3. Start the flow and wait for the data collection to complete.
4. Review the collected data in the GRR interface.

Expected Output: Collected forensic data from the remote endpoint, accessible in the GRR interface.

Exercise 4: Memory Analysis

Objective: Capture and analyze memory from a remote endpoint using GRR.

1. In the GRR web interface, select an endpoint and navigate to "Flows" > "Launch New Flow".
2. Choose "Memory Collector" to capture the memory image.
3. Start the flow and wait for the memory capture to complete.
4. Download the memory image and analyze it using Volatility:

   volatility -f memory.img --profile=LinuxProfile linux_pslist

Expected Output: Memory image captured and analyzed for forensic artifacts.

Exercise 5: Detecting Persistence Mechanisms

Objective: Identify and analyze persistence mechanisms on a remote endpoint.

1. In the GRR web interface, select an endpoint and navigate to "Flows" > "Launch New Flow".
2. Choose "ListProcesses" to list all running processes.
3. Start the flow and review the process list for suspicious entries.
4. Investigate the startup scripts and services:

   grr_client --list_startup_items
   grr_client --list_services

Expected Output: Identification of persistence mechanisms and analysis of suspicious processes and services.

Conclusion

By completing these exercises, you have gained advanced skills in using GRR Rapid Response for Linux endpoint forensics. You have learned to set up and configure the GRR server, deploy agents on endpoints, collect live forensic data, perform memory analysis, and detect persistence mechanisms. These skills are essential for conducting comprehensive remote forensic investigations and responding to security incidents effectively.

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