UEFITool

Advanced UEFITool Techniques for Firmware Reverse Engineering

Overview

Advanced UEFITool usage focuses on in-depth firmware parsing, targeted module extraction, safe on-image edits, and workflows that speed reverse engineering and vulnerability discovery.

Key techniques

1. Tree navigation & GUID identification

   • Traverse firmware tree to locate Volume/FS/Section nodes.
   • Map module GUIDs against known databases (Tiano, vendor OIDs) to identify DXE drivers, PEI modules, OROMs.

2. Selective extraction of modules

   • Extract DXE/PEI/UEFI apps and option ROMs as PE/ELF blobs for disassembly.
   • Preserve padding and alignments; use “Extract body” vs “Extract as is” depending on analysis tool needs.

3. PE/PE32 parsing and fixups

   • Use UEFITool’s PE parser to reconstruct PE headers and RDATA; fix missing imports and section attributes before loading in IDA/Ghidra/Binary Ninja.
   • Rebase and apply relocations if present; restore entry points.

4. Automated batch processing

   • Use UEFITool command-line to extract multiple images/modules programmatically for large-scale firmware corpora.
   • Combine with scripts (Python) to tag modules by GUID, export metadata CSV and feed into static analysis pipelines.

5. In-image patching and rebuilding

   • Replace or patch modules inside the firmware (e.g., removing signatures, swapping drivers) and rebuild images for testing.
   • Verify checksums and flash descriptor boundaries; keep a copy of original image and changes log.

6. NVRAM and variable analysis

   • Locate and extract NVRAM/variable store (NvVars) sections; parse UEFI variables for configuration, secure boot state, or hidden data.
   • Use efi variables parsers after extraction; detect persistent data-hiding techniques.

7. Finding and extracting SMM/SMRAM code

   • Identify SMM-related modules (using GUIDs and section types) and extract for offline analysis—watch for encrypted/compressed blobs.
   • Combine with SMM-specific tools to unpack and analyze privileged code.

8. Decompressing and unpacking blobs

   • Detect compressed sections (LZMA, Tiano compression) and decompress using appropriate tools (TianoCore utilities, python libs).
   • Handle vendor-specific packing or XOR/obfuscation patterns with custom scripts.

9. Cross-referencing with firmware databases

   • Match module versions and GUIDs with online repos (TianoCore, vendor repos, “awesome-uefi-security”) to find known vuln alerts and fixes.

10. Integration with reverse-engineering tools

    • Prepare modules for IDA/Ghidra/Binary Ninja: correct headers, supply type libraries (EDK II), and use plugins (efiXplorer, efiSeek, efi-resolver).
    • Export symbol hints and type info where available to speed analysis.

Safety and best practices

• Always work on copies; preserve original images and document edits.
• Validate rebuilt images with checksums and test in emulated environments (QEMU, virtual machines) before flashing.
• Keep an eye on license/firmware EULAs and legal constraints when sharing extracted modules.

Quick workflow (summary)

1. Load image → inspect tree → identify target GUIDs.
2. Extract modules (body/as-is) → decompress/fix PE headers.
3. Load into disassembler with UEFI-specific plugins → search for vulnerabilities.
4. Patch or replace modules in-image → rebuild → test in emulator.

If you want, I can provide a 6–8 step command-line script (UEFITool + Python) to batch-extract and prepare modules for IDA/Ghidra.