ET MALWARE Suspected TA399/SideWinder Related Activity (GET)

alert http $HOME_NET any -> $EXTERNAL_NET any (
    msg:"ET MALWARE Suspected TA399/SideWinder Related Activity (GET)";
    flow:established,to_server;
    http.method;
    content:"GET";
    http.uri;
    content:"/@/@/"; startswith; fast_pattern;
    content:".txt"; endswith;
    http.header_names;
    content:"|0d 0a|Host|0d 0a|Accept|0d 0a 0d 0a|"; bsize:18;
    reference:md5,7d025c9837fe3dd3438439b7e4341b87;
    reference:md5,b9bf6ad9cba6f6fde0f6a13ba36032e2;
    reference:url,mp.weixin.qq.com/s?__biz=MzI2MDc2MDA4OA==&mid=2247508655&idx=1&sn=b808c9a435b473e5dc957d1b34a79432&chksm=ea6655d8dd11dcce5db489b200b67463f251c5900402b9a1cb18c9e1d9d1c56adee066eb165e&scene=178&cur_album_id=1539799351089283075;
    classtype:trojan-activity;
    sid:2051558; rev:1;
    metadata:affected_product Windows_XP_Vista_7_8_10_Server_32_64_Bit, affected_product Windows_11, attack_target Client_Endpoint, tls_state plaintext, created_at 2024_03_08, deployment Perimeter, malware_family Sidewinder, confidence Medium, signature_severity Major, tag TA399, tag Description_Generated_By_Proofpoint_Nexus, updated_at 2024_03_08;
    target:src_ip;
)