/analyzing-bootkit-and-rootkit-samples

name: analyzing-bootkit-and-rootkit-samples
description: 'Analyzes bootkit and advanced rootkit malware that infects the Master Boot Record (MBR), Volume Boot Record
  (VBR), or UEFI firmware to gain persistence below the operating system. Covers boot sector analysis, UEFI module inspection,
  and anti-rootkit detection techniques. Activates for requests involving bootkit analysis, MBR malware investigation, UEFI
  persistence analysis, or pre-OS malware detection.

  '
domain: cybersecurity
subdomain: malware-analysis
tags:
- malware
- bootkit
- rootkit
- UEFI
- MBR-analysis
version: 1.0.0
author: mahipal
license: Apache-2.0
nist_csf:
- DE.AE-02
- RS.AN-03
- ID.RA-01
- DE.CM-01

Analyzing Bootkit and Rootkit Samples

When to Use

• A system shows signs of compromise that persist through OS reinstallation
• Antivirus and EDR are unable to detect malware despite clear evidence of compromise
• UEFI Secure Boot has been disabled or shows integrity violations
• Memory forensics reveals rootkit behavior (hidden processes, hooked system calls)
• Investigating nation-state level threats known to deploy bootkits (APT28, APT41, Equation Group)

**Do not use** for standard user-mode malware; bootkits and rootkits operate at a fundamentally different level requiring specialized analysis techniques.

Prerequisites

• Disk imaging tools (dd, FTK Imager) for acquiring MBR/VBR sectors
• UEFITool for UEFI firmware volume analysis and module extraction
• chipsec for hardware-level firmware security assessment
• Ghidra with x86 real-mode and 16-bit support for MBR code analysis
• Volatility 3 for kernel-level rootkit artifact detection
• Bootable Linux live USB for offline system analysis

Workflow

Step 1: Acquire Boot Sectors and Firmware

Extract MBR, VBR, and UEFI firmware for offline analysis:

# Acquire MBR (first 512 bytes of disk)
dd if=/dev/sda of=mbr.bin bs=512 count=1

# Acquire first track (usually contains bootkit code beyond MBR)
dd if=/dev/sda of=first_track.bin bs=512 count=63

# Acquire VBR (Volume Boot Record - first sector of partition)
dd if=/dev/sda1 of=vbr.bin bs=512 count=1

# Acquire UEFI System Partition
mkdir /mnt/efi
mount /dev/sda1 /mnt/efi
cp -r /mnt/efi/EFI /analysis/efi_backup/

# Dump UEFI firmware (requires chipsec or flashrom)
# Using chipsec:
python chipsec_util.py spi dump firmware.rom

# Using flashrom:
flashrom -p internal -r firmware.rom

# Verify firmware dump integrity
sha256sum firmware.rom

Step 2: Analyze MBR/VBR for Bootkit Code

Examine boot sector code for malicious modifications:

# Disassemble MBR code (16-bit real mode)
ndisasm -b16 mbr.bin > mbr_disasm.txt

# Compare MBR with known-good Windows MBR
# Standard Windows MBR begins with: EB 5A 90 (JMP 0x5C, NOP)
# Standard Windows 10 MBR: 33 C0 8E D0 BC 00 7C (XOR AX,AX; MOV SS,AX; MOV SP,7C00h)

python3 << 'PYEOF'
with open("mbr.bin", "rb") as f:
    mbr = f.read()

# Check MBR signature (bytes 510-511 should be 0x55AA)
if mbr[510:512] == b'\x55\xAA':
    print("[*] Valid MBR signature (0x55AA)")
else:
    print("[!] Invalid MBR signature")

# Check for known bootkit signatures
bootkit_sigs = {
    b'\xE8\x00\x00\x5E\x81\xEE': "TDL4/Alureon bootkit",
    b'\xFA\x33\xC0\x8E\xD0\xBC\x00\x7C\x8B\xF4\x50\x07': "Standard Windows MBR (clean)",
    b'\xEB\x5A\x90\x4E\x54\x46\x53': "Standard NTFS VBR (clean)",
}

for sig, name in bootkit_sigs.items():
    if sig in mbr:
        print(f"[{'!' if 'clean' not in name else '*'}] Signature match: {name}")

# Check partition table entries
print("\nPartition Table:")
for i in range(4):
    offset = 446 + (i * 16)
    entry = mbr[offset:offset+16]
    if entry != b'\x00' * 16:
        boot_flag = "Active" if entry[0] == 0x80 else "Inactive"
        part_type = entry[4]
        start_lba = int.from_bytes(entry[8:12], 'little')
        size_lba = int.from_bytes(entry[12:16], 'little')
        print(f"  Partition {i+1}: Type=0x{part_type:02X} {boot_flag} Start=LBA {start_lba} Size={size_lba} sectors")
PYEOF

Step 3: Analyze UEFI Firmware for Implants

Inspect UEFI firmware volumes for unauthorized modules:

# Extract UEFI firmware components with UEFITool
# GUI: Open firmware.rom -> Inspect firmware volumes
# CLI:
UEFIExtract firmware.rom all

# List all DXE drivers (most common target for UEFI implants)
find firmware.rom.dump -name "*.efi" -exec file {} \;

# Compare against known-good firmware module list
# Each UEFI module has a GUID - compare against vendor baseline

# Verify Secure Boot configuration
python chipsec_main.py -m common.secureboot.variables

# Check SPI flash write protection
python chipsec_main.py -m common.bios_wp

# Check for known UEFI malware patterns
yara -r uefi_malware.yar firmware.rom

Known UEFI Bootkit Detection Points:
━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━
LoJax (APT28):
  - Modified SPI flash
  - Added DXE driver that drops agent to Windows
  - Persists through OS reinstall and disk replacement

BlackLotus:
  - Exploits CVE-2022-21894 to bypass Secure Boot
  - Modifies EFI System Partition bootloader
  - Installs kernel driver during boot

CosmicStrand:
  - Modifies CORE_DXE firmware module
  - Hooks kernel initialization during boot
  - Drops shellcode into Windows kernel memory

MoonBounce:
  - SPI flash implant in CORE_DXE module
  - Modified GetVariable() function
  - Deploys user-mode implant through boot chain

ESPecter:
  - Modifies Windows Boot Manager on ESP
  - Patches winload.efi to disable DSE
  - Loads unsigned kernel driver

Step 4: Detect Kernel-Level Rootkit Behavior

Analyze the running system for rootkit artifacts:

# Memory forensics for rootkit detection
# SSDT hook detection
vol3 -f memory.dmp windows.ssdt | grep -v "ntoskrnl\|win32k"

# Hidden processes (DKOM)
vol3 -f memory.dmp windows.psscan > psscan.txt
vol3 -f memory.dmp windows.pslist > pslist.txt
# Diff to find hidden processes

# Kernel callback registration (rootkits register callbac