alert http $HOME_NET any -> $EXTERNAL_NET any (msg:"ET MALWARE Athena DDoS Bot Checkin"; flow:established,to_server; http.method; content:"POST"; nocase; http.header_names; content:!"Referer|0d 0a|"; http.request_body; content:"a=%"; depth:3; fast_pattern; content:"&b="; distance:0; content:"&c="; distance:0; pcre:"/^a=(?:%[0-9A-Fa-f]{2})+\x26b=[0-9A-Za-z]+(?:%3[dD]){0,2}\x26c=(?:%[0-9A-Fa-f]{2})+$/"; reference:md5,19ca0d830cd7b44e5de1ab85f4e17d82; classtype:command-and-control; sid:2017633; rev:5; metadata:created_at 2013_04_26, signature_severity Major, updated_at 2020_05_15;)