Penetration Testing mailing list archives
Overflowing Scripts fail to work
From: Paul Sebastian Ziegler <psz () observed de>
Date: Sat, 22 Apr 2006 10:30:43 +0200
Hallo list! I've been on this for quite some time and after failing to find out anything on the Internet I've finally decided to propose this question here. Any help would be greatly appreciated! Due to interest I have started to try to understand buffer-overflow-attacks. The theory is fine with me. But now I'm getting quite some trouble when trying to write exploiting scripts. Let me show you what I mean: The program I'll be using consists of those few lines of C-code. ###Content of test.c####################### #include <stdio.h> int main(int argc, char *argv[]) { char buffer[512]; setuid(0); seteuid(0); strcpy(buffer, argv[1]); printf("%s\n",buffer); return(0); } ########################################### This is more or less the average "vulnerable" Program. Ok; now I compile it and then have a go at it from the shell: -------------------------------------------------------------- xyz@localhost ~ $ ./test `python -c "print 'A' * 524"` AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA Speicherzugriffsfehler (core dumped) -------------------------------------------------------------- As expected the program crashes with a segmentation fault. When firing up gdb with the coredump it can also be seen that the segmentation fault was caused by the registers being filled with "41". So far so good. Now for the part that puzzles me: I put exactly the same thing into a script: ###Content of exp.py######################## #! /bin/env python import os os.system("./test "+("A" * 524)) ############################################ Now when I'm running it I get no overflow at all: ------------------------------------------------------------- xyz@localhost ~ $ ./exp.py AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA -------------------------------------------------------------- To make sure I increased the number of As until 10000. Still nothing happens. I don't know what do do with this. Some more information that might be of need: I'm running Gentoo-Linux with a 2.6.16-Kernel with the Gentoo-Patchset applied. Python version and C-Compiler: Python 2.4.2 (#1, Feb 5 2006, 10:03:22) [GCC 3.3.6 (Gentoo 3.3.6, ssp-3.3.6-1.0, pie-8.7.8)] on linux2 Any help would be greatly appreciated. Thanks in advance! If anyone should need any other information please tell me. MfG Paul ------------------------------------------------------------------------------ This List Sponsored by: Cenzic Concerned about Web Application Security? Why not go with the #1 solution - Cenzic, the only one to win the Analyst's Choice Award from eWeek. As attacks through web applications continue to rise, you need to proactively protect your applications from hackers. Cenzic has the most comprehensive solutions to meet your application security penetration testing and vulnerability management needs. You have an option to go with a managed service (Cenzic ClickToSecure) or an enterprise software (Cenzic Hailstorm). Download FREE whitepaper on how a managed service can help you: http://www.cenzic.com/news_events/wpappsec.php And, now for a limited time we can do a FREE audit for you to confirm your results from other product. Contact us at request () cenzic com for details. ------------------------------------------------------------------------------
Current thread:
- Overflowing Scripts fail to work Paul Sebastian Ziegler (Apr 23)
- Re: Overflowing Scripts fail to work Don Bailey (Apr 24)
- Re: Overflowing Scripts fail to work Bill Weiss (Apr 24)
- Re: Overflowing Scripts fail to work Gilles DEMARTY (Apr 24)
- Re: Overflowing Scripts fail to work Peter Kosinar (Apr 25)