alert http $HOME_NET any -> $EXTERNAL_NET any (msg:"ET INFO HTTP Request for ISO File Direct to IP"; flow:established,to_server; http.method; content:"GET"; http.host; pcre:"/^(?:\d{1,3}\.){3}\d{1,3}(?:\x3a\d+)?$/"; http.request_line; content:".iso HTTP/1."; fast_pattern; classtype:misc-activity; sid:2030205; rev:2; metadata:attack_target Client_Endpoint, created_at 2020_05_22, deployment Perimeter, confidence High, signature_severity Informational, tag Description_Generated_By_Proofpoint_Nexus, updated_at 2020_05_22;)