You probably need this UrlToolkit ruleset:
UrlToolkit {
ToolkitID = grav
Match base64_encode[^(]*\([^)]*\) DenyAccess
Match (<|%3C)([^s]*s)+cript.*(>|%3E) DenyAccess
Match GLOBALS(=|\[|\%[0-9A-Z]{0,2}) DenyAccess
Match _REQUEST(=|\[|\%[0-9A-Z]{0,2}) DenyAccess
Match ^/(.git|cache|bin|logs|backup|webserver-configs)/(.*) DenyAccess
Match ^/(system|vendor)/(.*)\.(txt|xml|md|html|yaml|php|pl|py|cgi|twig|sh|bat)$ DenyAccess
Match ^/(user)/(.*)\.(txt|md|yaml|php|pl|py|cgi|twig|sh|bat)$ DenyAccess
Match \.md$ DenyAccess
Match ^/(LICENSE.txt|composer.lock|composer.json|\.htaccess)$ DenyAccess
RequestURI exists Return
Match .* Rewrite /index.php
}
Please note that I haven't tested it. So, it could contain some minor mistakes or typos.