ET MALWARE SPEAR CnC Beacon

alert http $HOME_NET any -> $EXTERNAL_NET any (
    msg:"ET MALWARE SPEAR CnC Beacon";
    flow:to_server,established;
    http.method;
    content:"GET";
    http.uri;
    content:".asp?"; fast_pattern;
    pcre:"/\.asp\?(?:[A-Za-z0-9+*]{4})*(?:[A-Za-z0-9+*]{2}==|[A-Za-z0-9+*]{3}=|[A-Za-z0-9+*]{4})$/";
    http.user_agent;
    content:"|20|MSIE|20|";
    http.header_names;
    content:!"Accept";
    content:!"Referer|0d 0a|";
    reference:url,blog.cylance.com/spear-a-threat-actor-resurfaces;
    reference:md5,a69ac85c7e723ae37377516d7054fa0b;
    classtype:command-and-control;
    sid:2021118; rev:6;
    metadata:attack_target Client_Endpoint, created_at 2015_05_20, deployment Perimeter, performance_impact Moderate, signature_severity Major, tag c2, updated_at 2024_04_22, mitre_tactic_id TA0010, mitre_tactic_name Exfiltration, mitre_technique_id T1041, mitre_technique_name Exfiltration_Over_C2_Channel;
)