alert http $HOME_NET any -> $EXTERNAL_NET any (msg:"ET MALWARE Blackenergy Bot Checkin to C&C"; flow:established,to_server; http.method; content:"POST"; nocase; http.header; content:"Cache-Control|3a| no-cache"; http.request_body; content:"id="; content:"&build_id="; fast_pattern; pcre:"/id=x.+_[0-9A-F]{8}&build_id=./"; reference:url,asert.arbornetworks.com/2007/10/blackenergy-ddos-bot-analysis-available; classtype:command-and-control; sid:2007668; rev:18; metadata:created_at 2010_07_30, signature_severity Major, updated_at 2020_04_22;)