BinTut
Dynamic or live demonstration of classical exploitation techniques
of typical memory corruption vulnerabilities,
from debugging to payload generation and exploitation,
for educational purposes
Official Mirrors
- https://gitlab.com/imtheforce/bintut
- https://bitbucket.org/fourthorigin/bintut
- https://github.com/NoviceLive/bintut
What's BinTut
BinTut is a set of tutorials, as well as exercises.
Tutorials
See Get Started for usage information.
If you are a fan of Faiz, Burst Mode or Single Mode should
sound familiar and inspiring.
Burst Mode
Watch and replay to obtain general understanding of the process.
Use -b / --burst to control the interval (in seconds).
Note that -b0 means Single Mode, which is the default.
Single Mode
Play and examine various contents such as the stack, registers or memory addresses, carefully and step by step, to acquire comprehensive and detailed knowledge of the process.
Use Enter or Ctrl + D to step.
You can execute normal GDB commands via the promt.
But note that BinTut won't synchronize the display
when you execute state-changing commands,
e.g. stepi or nexti,
which are discouraged for the time being.
Another bad news is that readline does not work
Exercises
Write exploits that work outside debuggers
when you understand the principles and techniques
via watching and replaying (i.e. rewatching),
careful playing (i.e., Single Mode),
and most importantly,
reading the source code responsible for exploit generation,
which resides in a file named exploits.py.
Installation
Notice
If pip is used to install BinTut, make sure that you use the pip version corresponding to the Python version shipped with GDB. For more details, see #1.
pip install bintut may or may not work for the time being.
Therefore it's recommended to just clone this repository
and run without installation
as long as necessary libraries are installed
by pip install -r requirements.txt.
Warning
BinTut does not work inside virtualenv at present.
Tested Platforms
Arch GNU/Linux
Current version of Arch GNU/Linux ships GDB with Python 3, in which I developed BinTut.
The latest release version should work fine.
Install
lib32-glibcsudo pacman -S lib32-glibc
Install Python 3 and
pip3.sudo pacman -S python python-pip
Install BinTut using
pip3sudo pip3 install bintut
You are ready!
bintut -b0.1 jmp-esp
Fedora GNU/Linux
The latest Fedora Workstation comes with GDB with Python 3, which has been tested and BinTut is known to work properly as in Arch GNU/Linux.
Install
glibc.i686to support 32-bit programs if needed.sudo dnf install glibc.i686
Install
BinTutfrom PyPI.sudo pip3 install bintut
Give it a try.
bintut -b0.1 frame-faking
Debian GNU/Linux
GDB from the stable branch of Debian GNU/Linux ships with Python 2.
Latest source from Git works with minor problems.
Add support to 32-bit programs if necessary.
sudo dpkg --add-architecture i386 sudo apt-get update sudo apt-get install libc6:i386
Clone the latest source code from Git and install requirements.
git clone https://github.com/NoviceLive/bintut.git cd bintut sudo apt-get install python-pip gdb pip2 install -r requirements.txt
Run it without installation.
python2 ./bintut.py -b0.1 frame-faking
Kali GNU/Linux
GDB from the latest rolling version of Kali GNU/Linux ships with Python 3.
Enable
i386support according to aforementioned instructions.Install
pip3apt-get install python3-pip
Install the latest BinTut release using
pip3pip3 install bintut
Start hacking!
bintut -b0.1 jmp-esp
Requirements
GDB
Python scripting support is required.
BinTut is developed with Python 3, but it's intended to be Python 2 compatible.
Therefore, when Python 2 yells at you, feel free to create an issue or send me a pull request.
Known unresolved issues existing on Python 2
- Can't display disassembly after returning to shellcode.
- Can't print the payload for some courses.
Ropper
Show information about binary files and find gadgets to build rop chains for different architectures.
pyelftools
Python library for analyzing ELF files and DWARF debugging information.
Pat
Customizable Lazy Exploit Pattern Utility.
Colorama
Simple cross-platform colored terminal text in Python.
Click
Python composable command line utility.
Get Started
See bintut --help and give it a shot
via bintut --burst 0.1 frame-faking.
./bintut.py --help Usage: bintut.py [OPTIONS] [COURSE] Teach You A Binary Exploitation For Great Good. Options: -V, --version Show the version and exit. -l, --list List available courses. -6, --x64 Use x64 courses. -A, --aslr Enable ASLR. -b, --burst FLOAT Use this burst mode interval. [default: 0] -v, --verbose Be verbose. -q, --quiet Be quiet. -h, --help Show this message and exit.
Available Courses
Other courses might be added later.
Stack-based buffer overflow
1. plain
Return to plain shellcode.
Linux x86 / x64.
NX: Disabled.
ASLR: Disabled.
Stack Protector: Disabled.
2. nop-slide
Return to NOPs plus shellcode.
Linux x86 / x64.
NX: Disabled.
ASLR: Disabled.
Stack Protector: Disabled.
This course is not demonstrative enough and shall be updated when the author finds a scenario where nop-slide really stands out.
3. jmp-esp
Return to shellcode via JMP ESP / RSP.
Linux x86 / x64.
NX: Disabled.
ASLR: Disabled.
Stack Protector: Disabled.
4. off-by-one NULL
Variant of plain stack-based buffer overflow.
Linux x86 / x64.
NX: Disabled.
ASLR: Disabled.
Stack Protector: Disabled.
5. ret2lib
Return to functions.
Linux x86.
NX: Enabled.
ASLR: Disabled.
Stack Protector: Disabled.
Notes for x64
Either on Linux or Windows, the ABI of x64, unlike that of x86, passes some arguments, first six or four integral arguments on Linux or Windows respectively, via registers, which may not be controlled without resort to certain gadgets.
Therefore, it may be discussed in the section for ROP.
6. frame-faking
Return to chained functions via LEAVE RET gadget.
Linux x86.
NX: Enabled.
ASLR: Disabled.
Stack Protector: Disabled.
Notes for x64
See Notes for x64.
Bug Reports
Create issues.
BinTut might or might not work on your system, but bug reports with necessary information are always welcome.
Tips
Remember to include bintut --version in your report.
You can just submit the verbose log (stderr) if out of words,
e.g., bintut -v -b0.1 frame-faking 2>log.txt.
TODO List & You Can Contribute
Improve the code if you find something that can be done better.
The codebase of BinTut can always be improved by those who have a deeper understanding of Python than the author.
Also, there are hardcoded behaviors which can be generalized.
Change color scheme to red highlight when content changes.
Currently, our color scheme remains unchanged, in predefined colors, which is just not eye-catching or obvious when we want to observe some significant changes in certain registers or specific memory locations.
Here is an example of such change, the least-significant-byte of saved EBP / RBP being cleared due to an off-by-one NULL write.
Ref. That's what you will expect in OllyDbg and probably many other debuggers will also behave in this manner.
Ref. Some GDB enhancement projects have already implemented this.
Synchronize the display when executing state-changing commands.
Add course variants that does not allow NULL bytes.
For example, add variant courses using
strcpyinstead offreadto trigger overflow, in order to demonstrate the techniques to survive in severe environments, which happen to be the case of our real world.Use a better combination of chained functions for
frame-faking.What follows is the current choice.
Yes, two consecutive
/bin/shandexit.elif post == 'frame-faking': payload = ( Faked(offset=offset, address=addr) + Faked(b'system', ['/bin/sh']) + Faked(b'execl', ['/bin/sh', '/bin/sh', 0]) + Faked(b'exit', [0]))Support demonstration on Windows and MacOS.