/analyzing-uefi-bootkit-persistence

name: analyzing-uefi-bootkit-persistence
description: 'Analyzes UEFI bootkit persistence mechanisms including firmware implants in SPI flash, EFI System Partition
  (ESP) modifications, Secure Boot bypass techniques, and UEFI variable manipulation. Covers detection of known bootkit families
  (BlackLotus, LoJax, MosaicRegressor, MoonBounce, CosmicStrand), ESP partition forensic inspection, chipsec-based firmware
  integrity verification, and Secure Boot configuration auditing. Activates for requests involving UEFI malware analysis,
  firmware persistence investigation, boot chain integrity verification, or Secure Boot bypass detection.

  '
domain: cybersecurity
subdomain: firmware-security
tags:
- UEFI
- bootkit
- firmware
- Secure-Boot
- chipsec
- ESP
- persistence
version: 1.0.0
author: mukul975
license: Apache-2.0
d3fend_techniques:
- Platform Hardening
- Restore Object
- Platform Monitoring
- Firmware Verification
- Firmware Embedded Monitoring Code
nist_csf:
- ID.RA-01
- PR.PS-01
- PR.PS-02

Analyzing UEFI Bootkit Persistence

When to Use

• A compromised system re-establishes C2 communication after OS reinstallation or disk replacement
• Secure Boot has been tampered with, disabled, or shows unexpected Machine Owner Key (MOK) enrollment
• Firmware integrity verification fails against vendor-provided baselines
• Memory forensics reveals rootkit components loading during early boot phase
• Investigating advanced persistent threat (APT) campaigns known to deploy UEFI implants
• Auditing firmware security posture for enterprise endpoint hardening

**Do not use** for standard MBR-based bootkits on legacy BIOS systems without UEFI; use MBR/VBR bootkit analysis instead.

Prerequisites

• chipsec framework for SPI flash dumping, UEFI variable inspection, and firmware security modules
• UEFITool / UEFIExtract for firmware volume parsing and DXE driver extraction
• Python 3.8+ with struct, hashlib, subprocess, and os modules
• Bootable Linux live USB for offline analysis (avoid running compromised OS)
• Volatility 3 for memory forensics of boot-phase artifacts
• YARA with UEFI malware rule sets for pattern-based detection
• Access to vendor firmware baselines for integrity comparison

Workflow

Step 1: Dump SPI Flash Firmware

Acquire the UEFI firmware from the SPI flash chip for offline analysis:

# Using chipsec to dump SPI flash contents
python chipsec_util.py spi dump firmware_dump.rom

# Using flashrom as an alternative
flashrom -p internal -r firmware_dump.rom

# Verify dump integrity
sha256sum firmware_dump.rom

# Read SPI flash descriptor information
python chipsec_util.py spi info

# Check SPI flash region access permissions
python chipsec_main.py -m common.spi_access

# Verify BIOS write protection is enabled
python chipsec_main.py -m common.bios_wp

# Check SPI flash controller lock
python chipsec_main.py -m common.spi_lock

Step 2: Inspect UEFI Variables

Enumerate and analyze UEFI variables for unauthorized modifications:

# List all UEFI variables on a live system
python chipsec_util.py uefi var-list

# List UEFI variables from a SPI flash dump
python chipsec_util.py uefi var-list-spi firmware_dump.rom

# Read specific Secure Boot variables
python chipsec_util.py uefi var-read SecureBoot 8BE4DF61-93CA-11D2-AA0D-00E098032B8C
python chipsec_util.py uefi var-read SetupMode 8BE4DF61-93CA-11D2-AA0D-00E098032B8C
python chipsec_util.py uefi var-read PK 8BE4DF61-93CA-11D2-AA0D-00E098032B8C
python chipsec_util.py uefi var-read KEK 8BE4DF61-93CA-11D2-AA0D-00E098032B8C
python chipsec_util.py uefi var-read db D719B2CB-3D3A-4596-A3BC-DAD00E67656F

# Dump UEFI key databases for analysis
python chipsec_util.py uefi keys

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

Step 3: Analyze EFI System Partition (ESP)

Inspect the ESP for unauthorized or modified boot components:

# Mount ESP (typically the first FAT32 partition, ~100-500MB)
mkdir /mnt/esp
mount /dev/sda1 /mnt/esp

# List all files on ESP with timestamps
find /mnt/esp -type f -exec ls -la {} \;

# Check for BlackLotus indicators - custom directory under ESP:/system32/
ls -la /mnt/esp/system32/ 2>/dev/null

# Verify Windows Boot Manager signature
sigcheck -a /mnt/esp/EFI/Microsoft/Boot/bootmgfw.efi

# Hash all EFI binaries for comparison against known-good values
find /mnt/esp -name "*.efi" -exec sha256sum {} \;

# Check for unauthorized .efi files outside standard directories
find /mnt/esp -name "*.efi" | grep -v "Microsoft\|Boot\|ubuntu\|grub"

# Look for grubx64.efi planted by BlackLotus
find /mnt/esp -name "grubx64.efi" -exec sha256sum {} \;

# Examine MeasuredBoot logs for anomalies (Windows)
# Logs located at C:\Windows\Logs\MeasuredBoot\

Step 4: Scan Firmware for Known Bootkit Signatures

Analyze the firmware dump for known UEFI malware patterns:

# Extract all firmware modules with UEFIExtract
UEFIExtract firmware_dump.rom all

# Generate firmware module whitelist from vendor baseline
python chipsec_main.py -m tools.uefi.whitelist -a generate,baseline.json,firmware_vendor.rom

# Compare current firmware against whitelist
python chipsec_main.py -m tools.uefi.whitelist -a check,baseline.json,firmware_dump.rom

# Scan firmware with UEFI-specific YARA rules
yara -r uefi_bootkits.yar firmware_dump.rom

# Scan extracted modules individually
find firmware_dump.rom.dump -name "*.efi" -exec yara -r uefi_bootkits.yar {} \;

# Check for modified CORE_DXE module (targeted by MoonBounce, CosmicStrand)
# Compare GUID and hash against vendor baseline

Step 5: Detect Secure Boot Bypass Mechanisms

Check for known Secure Boot bypass techniques:

# Check if Secure Boot is enabled
python chipsec_main.py -m common.secureboot.variables

# Verify SMM (System Management Mode) protections
python chipsec_main.py -m common.smm

# Check SMM BIOS write protection
python chipsec_main.py -m common.bios_smi

# On W