alert tcp $EXTERNAL_NET any -> $HOME_NET any (msg:"ET MALWARE Dropper.Win32.Npkon Server Responce"; flow:from_server,established; content:"|40 1f|"; offset:1; depth:2; content:"|01|"; distance:1; within:1; content:"|10 00 00 00|"; distance:1; within:4; dsize:26; reference:md5,a7f4a7d08fa650a5f09a00519b944b0b; classtype:trojan-activity; sid:2013794; rev:1; metadata:created_at 2011_10_24, signature_severity Major, tag Description_Generated_By_Proofpoint_Nexus, updated_at 2019_07_26;)