alert http $EXTERNAL_NET any -> $HOME_NET $HTTP_PORTS (msg:"ET SCAN HTTP OPTIONS invalid method case"; flow:established,to_server; content:"options"; http_method; nocase; content:!"OPTIONS"; http_method; reference:url,www.w3.org/Protocols/rfc2616/rfc2616-sec9.html; classtype:bad-unknown; sid:2011034; rev:6; metadata:created_at 2010_07_30, confidence Medium, signature_severity Informational, updated_at 2019_07_26;)