ET MALWARE BlackMatter CnC Activity

alert http $HOME_NET any -> $EXTERNAL_NET any (
    msg:"ET MALWARE BlackMatter CnC Activity";
    flow:established,to_server;
    http.request_line;
    content:"POST /?"; startswith;
    http.header;
    content:"Accept|3a 20|*/*|0d 0a|Connection|3a 20|keep-alive|0d 0a|Accept-Encoding|3a 20|gzip, deflate, br|0d 0a|Content-Type|3a 20|text/plain|0d 0a|User-Agent|3a 20|"; startswith;
    http.header_names;
    content:"|0d 0a|Accept|0d 0a|Connection|0d 0a|Accept-Encoding|0d 0a|Content-Type|0d 0a|User-Agent|0d 0a|Host|0d 0a|Content-Length|0d 0a|Cache-Control|0d 0a 0d 0a|"; bsize:104;
    http.user_agent;
    content:"/";
    content:!"/"; distance:0;
    reference:md5,d0512f2063cbd79fb0f770817cc81ab3;
    classtype:command-and-control;
    sid:2033643; rev:1;
    metadata:affected_product Windows_XP_Vista_7_8_10_Server_32_64_Bit, attack_target Client_Endpoint, created_at 2021_08_02, deployment Perimeter, malware_family DarkSide, performance_impact Low, confidence High, signature_severity Major, tag Ransomware, tag Description_Generated_By_Proofpoint_Nexus, updated_at 2021_08_02;
)