tool mini-review: UEFI Reverse

UEFI Reverse (uefireverse) is a collection of tools to help with analysis of UEFI-based firwmare, written by Jethro Beekman (jethrogb). It consists of four tools.

1) EFI PE Run (efiperun): Load and run EFI PE image files on Linux.

DISCLAIMER: This program loads and runs PE image files. It does this without any protection mechanisms. Certain memory sections will be mapped writable and executable simultaneously. Do not run this on untrusted software. Think carefully before running this on trusted software. Load and run EFI PE image files on your favorite operation system (Linux). PE images are just x86 code that will run fine as long as the environment is correct. efiperun is to EFI as Wine is to Windows, but much less advanced. This tool is not meant for long-term use and only for debugging. There’s instrumentation everywhere, which is great for debugging but makes things slow.Memory generally doesn’t get freed. Most EFI functionality is not implemented. Functions that are implemented only provide the bare minimum. This tool aims to aid in debugging/reverse engineering by providing a framework that you can extend as necessary. By default, this program will load a PE image specified on the command-line, call the entry point, and exit once that returns. If the entry point does not return in 10 seconds, the program will abort with SIGALRM. Beyond running images, you can also extend this execution, with a “debug module”, an extension to efiperun that can run code before and after loading a PE image. This is useful to install protocols beforehand that the PE image will use or to access the protocols that the PE image installed afterwards.

See the tool’s readme, there are more ways to hook into the execution process.

2) GUID DataBase (guiddb): Create C source listing of TianoCore GUIDs.

A few programs that Scan EDK-II .DEC build files for GUIDs, and output them in C-source file format.

(There are about 4 GUID tools by different authors. One of these days, I’ll need to compare the various UEFI GUID tools’s output to see which’re more accurate…)

3) Memory Dump (memdmp): Tools to dump UEFI memory.

First, there’s a patch against UEFI Shell’s “memmap” dump memory command to pipe that to a file called “mdmp”. Then, run “dmp2seg” to convert that output file into many files with the actual memory contents. Then, run “make_elf.rb” to make a single ELF file with all the memory contents. The ELF file is not executable or anything, it’s just a convenient format to store memory segments.

4) Tree (tree): Ruby firmware tree on your filesystem.

A class file that will provides a Ruby tree abstraction for a firmware tree on your filesystem previously extracted by UEFITool’s UEFIExtract tool.

UEFI Reverse is a collection of some specialized UEFI research tools that may help augment your toolbox.

UEFI Reverse-aside, Jethro also has some TPMv2 project as well, that is worth checking out, if you use Linux and are into TPMs…

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