ET RETIRED Win32/Koi Stealer CnC Checkin (POST) M1

alert http $HOME_NET any -> $EXTERNAL_NET any (
    msg:"ET RETIRED Win32/Koi Stealer CnC Checkin (POST) M1";
    flow:established,to_server;
    urilen:65;
    http.method;
    content:"GET";
    http.uri;
    content:"/index.php?id="; startswith; fast_pattern;
    content:"&subid="; distance:36; within:7;
    pcre:"/^\/index\.php\?id=[a-f0-9]{8}-([a-f0-9]{4}-){3}[a-f0-9]{12}\&subid=[a-zA-Z0-9]{8}$/";
    http.header_names;
    content:"|0d 0a|Host|0d 0a|Connection|0d 0a 0d 0a|"; bsize:22;
    reference:md5,ef24aa4c496b5d9803e7e37ae0f8e649;
    classtype:trojan-activity;
    sid:2049816; rev:2;
    metadata:affected_product Windows_XP_Vista_7_8_10_Server_32_64_Bit, affected_product Windows_11, attack_target Client_Endpoint, created_at 2023_12_21, deployment Perimeter, former_category MALWARE, malware_family Win32_Koi, performance_impact Moderate, confidence High, signature_severity Major, updated_at 2025_04_17, reviewed_at 2025_04_17;
    target:src_ip;
)