alert http $HOME_NET any -> $EXTERNAL_NET any (msg:"ET MALWARE Sisproc update"; flow:to_server,established; http.uri; content:"/poll/update.txt"; http.header_names; content:!"Referer|0d 0a|"; reference:md5,f8b3fb4e5f8f1b3bd643e58f1015f9fc; classtype:trojan-activity; sid:2017725; rev:6; metadata:created_at 2013_11_16, signature_severity Major, tag Description_Generated_By_Proofpoint_Nexus, updated_at 2020_04_27;)