Bugtraq mailing list archives

Bypass XSS filter in PHPNUKE 7.9=>x

From: max () jestsuper pl
Date: 14 Dec 2005 17:00:37 -0000
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[Bypass XSS filter in PHPNUKE 7.9=>x cXIb8O3.21]

Author: Maksymilian Arciemowicz ( cXIb8O3 )
Date: 14.12.2005
from SECURITYREASON.COM

- --- 0.Description ---
PHP-Nuke is a Web Portal System, storytelling software, news system, online community or whatever you want to call it. 
Its goal is to have an automated web site to distribute news and articles with user system. Each user can submit 
comments to discuss the articles, similar to Slashdot and many others. Features: web admin, polls/surveys with comment, 
statistics, user customizable box, themes manager, friendly admin GUI, moderation system, sections manager, banner 
system, backend/headlines generation, Yahoo like search engine, Ephemerids manager, file manager, download manager, faq 
manager, advanced blocks system, reviews system, newsletter, content management, encyclopedia generator, md5 password 
encryption, phpBB Forums integration, support for 25 languages, 100% modular and more. Written 100% in PHP and requires 
Apache, PHP and a SQL Database Server. Supports MySQL, PostgreSQL, Adabas, mSQL and many others.

- --- 1. Bypass XSS filter ---

In PHPnuke is (file includes/mainfile.php).

- -168-193---
if (!defined('ADMIN_FILE') && !file_exists('includes/nukesentinel.php')) {
  foreach ($_GET as $sec_key => $secvalue) {
    if ((eregi("<[^>]*script*\"?[^>]*>", $secvalue)) ||
        (eregi("<[^>]*object*\"?[^>]*>", $secvalue)) ||
        (eregi("<[^>]*iframe*\"?[^>]*>", $secvalue)) ||
        (eregi("<[^>]*applet*\"?[^>]*>", $secvalue)) ||
        (eregi("<[^>]*meta*\"?[^>]*>", $secvalue)) ||
        (eregi("<[^>]*style*\"?[^>]*>", $secvalue)) ||
        (eregi("<[^>]*form*\"?[^>]*>", $secvalue)) ||
        (eregi("<[^>]*img*\"?[^>]*>", $secvalue)) ||
        (eregi("<[^>]*onmouseover*\"?[^>]*>", $secvalue)) ||
        (eregi("<[^>]*body*\"?[^>]*>", $secvalue)) ||
        (eregi("\([^>]*\"?[^)]*\)", $secvalue)) ||
        (eregi("\"", $secvalue)) ||
        (eregi("forum_admin", $sec_key)) ||
        (eregi("inside_mod", $sec_key))) {
        die ($htmltags);
     }
  }

  foreach ($_POST as $secvalue) {
    if ((eregi("<[^>]*onmouseover*\"?[^>]*>", $secvalue)) || (eregi("<[^>]script*\"?[^>]*>", $secvalue)) || 
(eregi("<[^>]*body*\"?[^>]*>", $secvalue)) || (eregi("<[^>]style*\"?[^>]*>", $secvalue))) {
      die ($htmltags);
    }
  }
}
- -168-193---

This functions deletes from input html tags like:

        - <script>
        - <object>
        - <iframe>
        - <applet>
        - <meta>
        - <style>
        - <form>
        - <img>
        - <onmouseover>
        - <body>
        
etc.

Ok. But if we sent to script:

# <iframe src=http://securityreason?    < Hi

The function don't find wrong tags.
And broswer read this 

"<iframe src=http://securityreason?    < Hi"

and change "<" to ">".
Result:

# <iframe src=http://securityreason?    > Hi

I have checked this in IE, Mozilla, Opera, Links, Lynx etc.
Only don't work in konqueror.

- --- 2. XSS ---

2.0 http://[HOST]/[DIR]/modules.php?name=Search

Insert:

<iframe src=http://securityreason.com?phpnuke79 <

And have you xss.

2.1 http://[HOST]/[DIR]/modules.php?name=Web_Links

Insert:

<iframe src=http://securityreason.com?phpnuke79 <

and more.

- --- 3. How to fix ---

Change xss filter in mainfile.php

- ---
if (!defined('ADMIN_FILE')) {
        foreach ($_GET as $sec_key => $secvalue) {
                if ((eregi("<[^>]*script*\"?[^>]*>", $secvalue)) ||
                (eregi("<[^>]*object*\"?[^>]*>", $secvalue)) ||
                (eregi("<[^>]*iframe*\"?[^>]*>", $secvalue)) ||
                (eregi("<[^>]*applet*\"?[^>]*>", $secvalue)) ||
                (eregi("<[^>]*meta*\"?[^>]*>", $secvalue)) ||
                (eregi("<[^>]*style*\"?[^>]*>", $secvalue)) ||
                (eregi("<[^>]*form*\"?[^>]*>", $secvalue)) ||
                (eregi("<[^>]*img*\"?[^>]*>", $secvalue)) ||
                (eregi("<[^>]*onmouseover*\"?[^>]*>", $secvalue)) ||
                (eregi("\([^>]*\"?[^)]*\)", $secvalue)) ||
                (eregi("\"", $secvalue)) ||
                (eregi("forum_admin", $sec_key)) ||
                (eregi("inside_mod", $sec_key))) {
                        die ("<center><img src=images/logo.gif><br><br><b>The html tags you attempted to use are not 
allowed</b><br><br>[ <a href=\"javascript:history.go(-1)\"><b>Go Back</b></a> ]");
                }
        }
        
        foreach ($_POST as $secvalue) {
                if ((eregi("<[^>]*onmouseover*\"?[^>]*>", $secvalue)) || (eregi("<[^>]script*\"?[^>]*>", $secvalue)) || 
(eregi("<[^>]style*\"?[^>]*>", $secvalue))) {
                        die ("<center><img src=images/logo.gif><br><br><b>The html tags you attempted to use are not 
allowed</b><br><br>[ <a href=\"javascript:history.go(-1)\"><b>Go Back</b></a> ]");
                }
        }
} 
- ---

to

- ---
if (!defined('ADMIN_FILE')) {
        foreach ($_GET as $sec_key => $secvalue) {
        if((eregi("<[^>]*script*\"?[^>]*", $secvalue)) ||
                (eregi("<[^>]*object*\"?[^>]*", $secvalue)) ||
                (eregi("<[^>]*iframe*\"?[^>]*", $secvalue)) ||
                (eregi("<[^>]*applet*\"?[^>]*", $secvalue)) ||
                (eregi("<[^>]*meta*\"?[^>]*", $secvalue)) ||
                (eregi("<[^>]*style*\"?[^>]*", $secvalue)) ||
                (eregi("<[^>]*form*\"?[^>]*", $secvalue)) ||
                (eregi("<[^>]*img*\"?[^>]*", $secvalue)) ||
                (eregi("<[^>]*onmouseover *\"?[^>]*", $secvalue)) ||
                (eregi("<[^>]*body *\"?[^>]*", $secvalue)) ||
                (eregi("\([^>]*\"?[^)]*\)", $secvalue)) ||
                (eregi("\"", $secvalue)) ||
                (eregi("forum_admin", $sec_key)) ||
                (eregi("inside_mod", $sec_key))) 
                {
                        die ($htmltags);
                }

        }

        foreach ($_POST as $secvalue) {
                if ((eregi("<[^>]*iframe*\"?[^>]*", $secvalue)) ||
                (eregi("<[^>]*object*\"?[^>]*", $secvalue)) ||
                (eregi("<[^>]*applet*\"?[^>]*", $secvalue)) ||
                (eregi("<[^>]*meta*\"?[^>]*", $secvalue)) ||
                (eregi("<[^>]*form*\"?[^>]*", $secvalue)) ||
                (eregi("<[^>]*img*\"?[^>]*", $secvalue)) ||
                (eregi("<[^>]*onmouseover*\"?[^>]*", $secvalue)) ||
                (eregi("<[^>]script*\"?[^>]*", $secvalue)) ||
                (eregi("<[^>]*body*\"?[^>]*", $secvalue)) ||
                (eregi("<[^>]style*\"?[^>]*", $secvalue))) 
                {
                        die ($htmltags);
                }
        }
}
- ---

thx nukefixes.com


- --- 4. Greets ---

sp3x, nukefixes.com

- --- 5.Contact ---
Author: Maksymilian Arciemowicz < cXIb8O3 >
Email: max [at] jestsuper [dot] pl or cxib [at] securityreason [dot] com
GPG-KEY: http://securityreason.com/key/Arciemowicz.Maksymilian.gpg
SecurityReason.Com
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Current thread:

Bypass XSS filter in PHPNUKE 7.9=>x max (Dec 14)
- Re: Bypass XSS filter in PHPNUKE 7.9=>x Paul Laudanski (Dec 17)