alert http $HOME_NET any -> $EXTERNAL_NET any (msg:"ET HUNTING Possible External IP Check"; flow:established,to_server; http.uri; content:".php?action=check_ip&ip="; fast_pattern; http.header_names; content:!"Referer|0d 0a|"; classtype:misc-activity; sid:2051870; rev:1; metadata:attack_target Client_Endpoint, created_at 2024_04_01, deployment Perimeter, confidence High, signature_severity Informational, tag Description_Generated_By_Proofpoint_Nexus, updated_at 2024_04_01; target:src_ip;)