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https://github.com/christhecoolhut/zeratool

Automatic Exploit Generation (AEG) and remote flag capture for exploitable CTF problems
https://github.com/christhecoolhut/zeratool

aeg angr buffer-overflow ctf shellcode solver

Last synced: 29 days ago
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Automatic Exploit Generation (AEG) and remote flag capture for exploitable CTF problems

Host: GitHub
URL: https://github.com/christhecoolhut/zeratool
Owner: ChrisTheCoolHut
License: gpl-3.0
Created: 2018-06-23T16:27:24.000Z (over 6 years ago)
Default Branch: master
Last Pushed: 2023-09-10T17:51:53.000Z (about 1 year ago)
Last Synced: 2024-08-30T15:28:36.506Z (3 months ago)
Topics: aeg, angr, buffer-overflow, ctf, shellcode, solver
Language: Python
Size: 2.6 MB
Stars: 1,103
Watchers: 33
Forks: 148
Open Issues: 8
Metadata Files:
- Readme: README.md
- License: LICENSE

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README

# Zeratool v2.2
Automatic Exploit Generation (AEG) and remote flag capture for exploitable CTF problems

This tool uses [angr](https://github.com/angr/angr) to concolically analyze binaries by hooking printf and looking for [unconstrained paths](https://github.com/angr/angr-doc/blob/master/docs/examples.md#vulnerability-discovery). These program states are then weaponized for remote code execution through [pwntools](https://github.com/Gallopsled/pwntools) and a series of script tricks. Finally the payload is tested locally then submitted to a remote CTF server to recover the flag.

[![asciicast](https://asciinema.org/a/457964.svg)](https://asciinema.org/a/457964)

## Version 2.2 changes

Zeratool now supports remote libc leaking with buffer overflows. When a `puts` or `printf` call is present, Zeratool will leak out remote GOT entries and submit them to an online libc searching database to find offsets without the need for a local copy of the library.

[See remote libc leak in action!](https://asciinema.org/a/LL2ASZkIwEdwR0xsnzMb3oFLp)

Zeratool supports some basic ret2dlresolve chaining for 64bit binaries. See the example below on how to run it.

## Version 2.1 changes

Zeratool now supports some smart rop chain generation. During a buffer overflow
Zeratool will attempt to leak a libc address and compute the base address and build a execve(/bin/sh,NULL,NULL) chain or system(/bin/sh) chain.

## Installing
Zeratool has been tested on Ubuntu 16.04 through 20.04. Please install [radare2](https://github.com/radareorg/radare2) first

pip install zeratool

## Usage
Zeratool is a python script which accept a binary as an argument and optionally a linked libc library, and a CTF Server connection information

```
[chris:~/Zeratool] zerapwn.py -h
usage: zerapwn.py [-h] [-l LIBC] [-u URL] [-p PORT] [-v] [--force_shellcode] [--force_dlresolve] [--skip_check] [--no_win] [--format_only] [--overflow_only] file

positional arguments:
file File to analyze

optional arguments:
-h, --help show this help message and exit
-l LIBC, --libc LIBC libc to use
-u URL, --url URL Remote URL to pwn
-p PORT, --port PORT Remote port to pwn
-v, --verbose Verbose mode
--force_shellcode Set overflow pwn mode to point to shellcode
--force_dlresolve Set overflow pwn mode to use ret2dlresolve
--skip_check Skip first check and jump right to exploiting
--no_win Skip win function checking
--format_only Only run format strings check
--overflow_only Only run overflow check

```

## Exploit Types
Zeratool is designed around weaponizing buffer overflows and format string vulnerabilities and currently supports a couple types:

* Buffer Overflow
* Point program counter to win function
* Point program counter to shellcode
* Point program counter to rop chain
* Rop chains will attempt to leak a libc function
* Rop chains will then execve(/bin/sh) or system(/bin/sh)
* Can attempt a ret2dlresolve ropchain
* Can attempt to use puts/printf to leak remote libc
* Format String
* Point GOT entry to win function
* Point GOT entry to shellcode

## Examples
Checkout the samples.sh file. The file contains several examples of Zeratool automatically solving exploitable CTF problems.

```
#!/bin/bash
# Buffer Overflows with win functions
zerapwn.py tests/bin/bof_win_32
zerapwn.py tests/bin/bof_win_64
# Buffer Overflows with ropping
zerapwn.py tests/bin/bof_nx_32
zerapwn.py tests/bin/bof_nx_64
# Buffer Overflow with ropping and libc leak
zerapwn.py tests/bin/bof_nx_64 -l tests/bin/libc.so.6_amd64

#Format string leak
zerapwn.py tests/bin/read_stack_32
zerapwn.py tests/bin/read_stack_64
#Format string point to win function
zerapwn.py challenges/medium_format
#Format string point to shellcode
#zerapwn.py challenges/hard_format #This one sometimes needs to be run twice

# Buffer overflow point to shellcode
# Turn off aslr
# echo 0 | sudo tee /proc/sys/kernel/randomize_va_space
zerapwn.py tests/bin/bof_32 --force_shellcode
zerapwn.py tests/bin/bof_64 --force_shellcode

# Remote libc leak
socat TCP4-LISTEN:7903,tcpwrap=script,reuseaddr,fork EXEC:./bof_nx_64
zerapwn.py tests/bin/bof_nx_64 -u localhost -p 7903 --skip_check --overflow_only

# Ret2dlresolve
zerapwn.py tests/bin/bof_dlresolve_64 --force_dlresolve --skip_check --overflow_only --no_win
```

[Long Asciinema with Three Solves](https://asciinema.org/a/188001)

## Run the tests!
Tox and Pytest are used to verify that Zeratool is working correctly.
```
tox .
```

## FAQ
Q. Why doesn't Zeratool work against my simple exploitable?

A. Zeratool is held together by scotch tape and dreams.