Analyzing Linux Kernel Rootkits
Overview
Linux kernel rootkits operate at ring 0, modifying kernel data structures to hide processes, files, network connections, and kernel modules from userspace tools. Detection requires either memory forensics (analyzing physical memory dumps with Volatility3) or cross-view analysis (comparing /proc, /sys, and kernel data structures for inconsistencies). This skill covers using Volatility3 Linux plugins to detect syscall table hooks, hidden kernel modules, and modified function pointers, supplemented by live system scanning with rkhunter and chkrootkit.
Prerequisites
- Volatility3 installed (pip install volatility3)
- Linux memory dump (acquired via LiME, AVML, or /proc/kcore)
- Volatility3 Linux symbol table (ISF) matching the target kernel version
- rkhunter and chkrootkit for live system scanning
- Reference known-good kernel image for comparison
Steps
Step 1: Acquire Memory Dump
Capture Linux physical memory using LiME kernel module or AVML for cloud instances.
Step 2: Analyze with Volatility3
Run linux.check_syscall, linux.lsmod, linux.hidden_modules, and linux.check_idt plugins to detect rootkit artifacts.
Step 3: Cross-View Analysis
Compare module lists from /proc/modules, lsmod, and /sys/module to identify modules hidden from one view but present in another.
Step 4: Live System Scanning
Run rkhunter and chkrootkit to detect known rootkit signatures, suspicious files, and modified system binaries.
Expected Output
JSON report containing detected syscall hooks, hidden kernel modules, modified IDT entries, suspicious /proc discrepancies, and rkhunter findings.