alert http $EXTERNAL_NET any -> $HOME_NET any (msg:"ET DELETED Nulprot Checkin Response"; flow:established,from_server; content:"200"; http_stat_code; content:"Encryption|3a| on|0d 0a|Content-Length|3a| "; http_header; depth:32; classtype:trojan-activity; sid:2007669; rev:11; metadata:created_at 2010_07_30, signature_severity Unknown, tag Description_Generated_By_Proofpoint_Nexus, updated_at 2019_07_26;)