ET MALWARE PurpleFox Backdoor/Rootkit Download Server Response M4

alert http $EXTERNAL_NET any -> $HOME_NET any (
    msg:"ET MALWARE PurpleFox Backdoor/Rootkit Download Server Response M4";
    flow:established,to_client;
    http.stat_code;
    content:"200";
    http.content_type;
    content:"application/octet-stream"; bsize:24;
    http.server;
    content:"HFS|20|"; startswith; fast_pattern;
    http.cookie;
    content:"HFS_SID_="; startswith;
    http.header;
    content:"|0d 0a|Content|2d|Disposition|3a 20|attachment|3b 20|filename|2a 3d|UTF|2d|8|27 27|";
    content:"|3b 20|filename="; distance:1; within:11;
    content:"|0d 0a|"; distance:1; within:2; endswith;
    http.response_body;
    content:"Rar|21 1A 07|"; startswith;
    content:"|2e|lnk"; within:150;
    reference:md5,930d405c7653dcf36c04e75224a2ff9d;
    reference:url,www.trendmicro.com/en_us/research/22/c/purple-fox-uses-new-arrival-vector-and-improves-malware-arsenal.html;
    classtype:command-and-control;
    sid:2035622; rev:1;
    metadata:created_at 2022_03_28, confidence High, signature_severity Major, tag Description_Generated_By_Proofpoint_Nexus, updated_at 2022_03_28;
)