[MajorSecurity #25] Advanced Guestbook 2.4 for phpBB - Multiple XSS and 
SQL-Injection Vulnerabilities

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Software: Advanced Guestbook for phpBB


Version: 2.4


Type: Cross site scripting + SQL Injection


Made public: July, 22th 2006 


Author: Dreamy and Kooky


Page: http://www.phpbbhacks.com/viewhack.php?id=966



Credits:

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Discovered by: David Vieira-Kurz

http://www.majorsecurity.de


Original Advisory:

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http://www.majorsecurity.de/advisory/major_rls25.txt


Affected Products:

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Advanced Guestbook for phpBB 2.4


Description:

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Advanced Guestbook is a PHP-based guestbook script. 

It includes many useful features such as preview, templates, e-mail 
notification, picture upload, page spanning , 

html tags handling, smilies, advanced guestbook codes and language support. 

The admin script lets you modify, view, and delete messages. Requires PHP4 and 
MySQL.


Requirements:

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register_globals = On


Vulnerabilities:

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XSS:

Input passed directly to the "entry" parameter in "guestbook.php" is not 
properly sanitised before being returned to the user.

This can be exploited to execute arbitrary HTML and script code in a user's 
browser session in context of an affected site.

It works with a script code like this:


>"><script%20%0a%0d>alert(123456789)%3B</script>


SQL Injection:

Input passed directly to the "entry" parameter in "guestbook.php" is not 
properly sanitised before being used in a SQL query.

This can be exploited to manipulate SQL queries by injecting arbitrary SQL code.


Solution:

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Edit the source code to ensure that input is properly sanitised.

You should work with "htmlspecialchars()" or "htmlentities()" php-function to 
ensure that html tags

are not going to be executed. You should also work with the "intval()" 
php-function to ensure that the input

is numeric. 


Example:

<?php

  $pass = htmlentities($_POST['pass']);

  echo htmlspecialchars("<script");

  $id = intval($_POST['id']);

?>


Set "register_globals" to "Off".

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