alert http $HOME_NET any -> $EXTERNAL_NET any (msg:"ET MALWARE AHK/BKDR_HTV.ZKGD-A CnC Checkin"; flow:established,to_server; threshold:type limit, count 1, seconds 30, track by_src; http.method; content:"POST"; http.uri; content:".php"; endswith; http.request_body; content:"&string="; depth:8; fast_pattern; pcre:"/^[A-F0-9]+$/R"; http.content_type; content:"|20|Charset=UTF-8"; endswith; http.header_names; content:!"Referer"; reference:url,blog.trendmicro.co.jp/archives/19054; classtype:command-and-control; sid:2027155; rev:3; metadata:affected_product Windows_XP_Vista_7_8_10_Server_32_64_Bit, attack_target Client_Endpoint, created_at 2019_04_04, deployment Perimeter, malware_family BKDR_HTV_ZKGD_A, performance_impact Low, confidence High, signature_severity Major, updated_at 2020_09_17;)