alert http $EXTERNAL_NET any -> $HOME_NET any (msg:"ET INFO Hide Referer Service (nullrefer .net)"; flow:established,to_client; http.location; content:"https://nullrefer.net/?"; fast_pattern; startswith; classtype:misc-activity; sid:2059249; rev:1; metadata:attack_target Client_Endpoint, created_at 2025_01_14, deployment Perimeter, confidence High, signature_severity Informational, updated_at 2025_01_14;)