Rootkit Detection and Analysis in Linux

Introduction

Rootkits are malicious software designed to hide the existence of certain processes or programs from normal methods of detection, allowing continued privileged access to a system. Detecting and analyzing rootkits is a crucial skill for cybersecurity professionals. This lab will guide you through intermediate-level techniques for detecting and analyzing rootkits on a Linux system.

Category: Digital Forensics and Incident Response
Sub-Category: Linux Forensics
Level: Intermediate

Pre-requisites

Intermediate understanding of Linux commands and file system structure.
Basic knowledge of rootkits and their functionalities.
A Linux system or virtual machine with sudo privileges.
Familiarity with command-line interface (CLI).

Lab Setup and Tools

Lab Setup

Install a Linux distribution (e.g., Ubuntu, Fedora) on your system or set up a virtual machine using VirtualBox or VMware.
Ensure you have sudo access to install necessary tools and perform analysis.

Tools

chkrootkit - Rootkit detection tool
rkhunter - Rootkit Hunter, a rootkit scanner
unhide - Detect hidden processes and ports
strace - System call tracer
lsmod - Display loaded kernel modules
modinfo - Show information about a kernel module
strings - Find printable strings in files

Exercises

Exercise 1: Scanning for Rootkits with Chkrootkit

Objective: Learn how to use chkrootkit to scan for common rootkits and suspicious activities on a Linux system.

Step1: Install chkrootkit:

   sudo apt-get install chkrootkit

Expected Output: chkrootkit installed on the system.

Step2: Run chkrootkit scan

sudo chkrootkit

Expected Output: Scan results showing potential rootkits and suspicious files.

Step3: Analyze chkrootkit results:

less /var/log/chkrootkit.log

Expected Output: Detailed log of the scan results for further analysis.

Exercise 2: Scanning for Rootkits with Rootkit Hunter (rkhunter)

Objective: Understand how to use rkhunter to detect rootkits, backdoors, and local exploits on a Linux system.

Step1: Install rkhunter:

sudo apt-get install rkhunter

Expected Output: rkhunter installed on the system.

Step2: Update rkhunter database:

sudo rkhunter --update

Expected Output: rkhunter database updated with the latest rootkit signatures.

Step3: Run rkhunter scan:

sudo rkhunter --check

Expected Output: Scan results showing potential rootkits and suspicious files.

Step4: Analyze rkhunter results:

less /var/log/rkhunter.log

Expected Output: Detailed log of the scan results for further analysis.

Exercise 3: Detecting Hidden Processes and Ports with Unhide

Objective: Learn how to use unhide to detect hidden processes and network ports that may indicate the presence of a rootkit.

Step1: Install unhide

sudo apt-get install unhide

Expected Output: unhide installed on the system.

Step2: Detect hidden processes:

sudo unhide proc

Expected Output: List of hidden processes detected on the system.

Step3: Detect hidden network ports:

sudo unhide-tcp

Expected Output: List of hidden network ports detected on the system.

Exercise 4: Analyzing Kernel Modules for Rootkits

Objective: Understand how to analyze loaded kernel modules to detect and investigate suspicious modules that may be part of a rootkit.

Step1: List loaded kernel modules:

lsmod

Expected Output: List of currently loaded kernel modules.

Step2: Get detailed information about a module:

modinfo <module_name>

Expected Output: Detailed information about the specified kernel module.

Step3: Check for suspicious modules:

lsmod | grep -i "rootkit"

Expected Output: Check if any loaded modules have names that might indicate they are rootkits.

Exercise 5: Using Strace to Monitor System Calls

Objective: Learn how to use strace to trace system calls and signals, helping to detect abnormal behavior that might indicate rootkit activity.

Step1: Install strace:

sudo apt-get install strace

Expected Output: strace installed on the system.

Step2: Trace system calls of a running process:

sudo strace -p <pid>

Expected Output: Real-time display of system calls made by the specified process.

Step3: Analyze strace output:

sudo strace -o strace_output.txt -p <pid>
less strace_output.txt

Expected Output: Detailed trace of system calls written to a file for further analysis.

Conclusion

By completing these exercises, you will gain an intermediate-level understanding of rootkit detection and analysis on Linux systems, enabling you to effectively identify and investigate rootkit infections.

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