GEF - GDB Enhanced Features

TL;DR: GEF is a kick-ass set of commands for X86, ARM, MIPS, PowerPC and SPARC to make GDB cool again for exploit dev.

GEF is aimed to be used mostly by exploiters and reverse-engineers. It provides additional features to GDB using the Python API to assist during the process of dynamic analysis or exploit development.

GEF fully relies on GDB API and other Linux specific source of information (such as /proc/pid). As a consequence, some of the features might not work on custom or harden systems such as GrSec. It has full support for Python2 and Python3 indifferently (as more and more distro start pushing gdb compiled with Python3 support).

Quick start

Install

Simply make sure you have GDB 7.x+.

# via the install script
$ wget -q -O- https://github.com/hugsy/gef/raw/master/gef.sh | sh

# manually
$ wget -q -O ~/.gdbinit-gef.py https://github.com/hugsy/gef/raw/master/gef.py
$ echo source ~/.gdbinit-gef.py >> ~/.gdbinit

Then just start playing (for local files):

$ gdb -q /path/to/my/bin
gef➤  gef help

Or (for remote debugging):

remote:~ $ gdbserver 0.0.0.0:1234 /path/to/file
Running as PID: 666

And:

local:~ $ gdb -q
gef➤  gef-remote -t your.ip.address:1234 -p 666

Update

If your host/VM is connected to Internet, you can update gef easily to the latest version (even without git installed)

$ python /path/to/gef.py --update
Updated

For example,

$ python ~/.gdbinit-gef.py --update
Updated

If no updates are available, gef will respond No update instead.

Show me

x86

ARM

PowerPC

MIPS

SPARC v9

Dependencies

There are none: GEF works out of the box! However, to enjoy all the coolest features, it is highly recommended to install:

{Cap,Key}stone

capstone (by Nguyen Anh Quynh) is an alternative disassembly engine, and keystone is an (arguably the best) assembly engine. You can use pip to simply and quickly install it.

$ pip2 install capstone keystone-engine  # for Python2.x
$ pip3 install capstone keystone-engine  # for Python3.x

capstone and keystone are under very active development and improvement, so it is recommended to compile and install them from git.

$ git clone https://github.com/keystone-engine/keystone.git
$ mkdir -p keystone/build && cd keystone/build
$ cmake .. && make -j8
$ sudo make install
$ cd ../bindings/python && sudo make install # or sudo make install3 for Python3

capstone provides an alternative to the gdb disassembler, which could be useful specifically when dealing with complex/uncommon instructions.

keystone allows to generate opcodes, which can, for example, then be used as part of a shellcode.

Unicorn

unicorn (also written by Nguyen Anh Quynh) is a lightweight Qemu-based framework to emulate any architecture currently supported by GDB (and even some more). Install is simple through the released packages but I would recommend instead to rely on the GIT master branch.

$ git clone https://github.com/unicorn-engine/unicorn.git && cd unicorn && ./make.sh && sudo ./make.sh install

unicorn integration in gef allows to emulate the behaviour to specific instructions (or block of instructions) based on the runtime context, without actually running it, and therefore sparing the trouble of saving the context/running the new context/restoring the old context. Additionally, gef can generate a standalone unicorn Python script, if you want/need to reproduce steps outside the debugger.

ROPGadget

ROPgadget (written by Jonathan Salwan) is simply the best cross-platform ROP gadget finder. It has been totally integrated inside gef to benefit of all of its awesomeness.

$ pip[23] install ropgadget

Ropper

Ropper (written by Sascha Schirra) is another gadget finder. It supports opening multiple files and provides an awesome search option to find accurate gadgets.

$ pip[23] install ropper

One-liner

Some of the optional dependencies can be installed using Python package installer, pip. Simply run this

$ pip[23] install ropgadget ropper capstone

But why not PEDA?

Yes ! Why not ?! PEDA is a fantastic tool to do the same, but is only to be used for x86-32 or x86-64. Whereas GEF supports all the architecture supported by GDB (currently x86, ARM, AARCH64, MIPS, PowerPC, SPARC) but is designed to integrate new architectures very easily as well!

Bugs & Feedbacks

To discuss gef, gdb, exploitation or other topic, feel free to join the channel ##gef on Freenode IRC network. You can also to me (hugsy) via the channel. For those who do not have an IRC client (like weechat or irssi), simply click here.

For bugs or feature requests, just go here and provide thorough description if you want help.

Contribution

gef was created and maintained by myself, @_hugsy_, but kept fresh thanks to all the contributors.

Open-Source Rewards

I love Open-Source, and just like my other projects I've decided to offer a 🍺 4 🐛 (a.k.a beer4bugs) bounty for GEF, to thank everybody who helps keeping the project living and always better.

The rule is simple, provide a (substantial) contribution to GEF, such as:

Submitting a Pull-Request for a new feature/command
Submitting a Pull-Request for a new architecture support
Or sending a relevant issue request (like a bug, crash, or else)

Poke me on the IRC ##gef channel about it, and next time we meet in person (like at a conference), I'll be happy to pay you a beer.

I do also accept beers if you think that the tool is cool 😉

Cheers 🍻

lillypad/gef