alert http $HOME_NET any -> $EXTERNAL_NET any (msg:"ET MALWARE W32/Numnet.Downloader CnC Checkin 2"; flow:established,to_server; http.uri; content:"/check_counter.php?pid="; fast_pattern; content:"&mid="; http.user_agent; content:"internet"; bsize:8; reference:md5,fbc732c7cd1bbd84956b1e76b53384da; classtype:command-and-control; sid:2015021; rev:3; metadata:created_at 2012_07_04, signature_severity Major, updated_at 2020_04_21;)