alert http $HOME_NET any -> $EXTERNAL_NET any (msg:"ET MALWARE H1N1 Loader CnC Beacon M1"; flow:established,to_server; http.method; content:"POST"; http.uri; content:"/gate.php"; fast_pattern; endswith; http.header; content:"Accept|3a 20|*/*|0d 0a|accept-Encoding|3a 20|none|0d 0a|accept-Language|3a 20|"; depth:53; http.request_body; pcre:"/^[A-Za-z0-9/_]+={0,2}$/"; http.header_names; content:!"Referer|0d 0a|"; reference:url,kernelmode.info/forum/viewtopic.php?f=16&t=3851; classtype:command-and-control; sid:2021139; rev:4; metadata:attack_target Client_Endpoint, created_at 2015_05_22, deployment Perimeter, signature_severity Major, tag c2, updated_at 2020_10_01, mitre_tactic_id TA0010, mitre_tactic_name Exfiltration, mitre_technique_id T1041, mitre_technique_name Exfiltration_Over_C2_Channel;)