ET MALWARE Unknown Possibly Ransomware (Dropped by RIG) CnC Beacon

alert http $HOME_NET any -> $EXTERNAL_NET !80 (
    msg:"ET MALWARE Unknown Possibly Ransomware (Dropped by RIG) CnC Beacon";
    flow:established,to_server;
    urilen:1;
    http.method;
    content:"POST";
    http.header;
    content:"Accept|3a 20|*|0d 0a|"; fast_pattern;
    http.request_body;
    content:"|0a|"; offset:64; depth:1;
    pcre:"/^[A-Za-z0-9+/]{64}\x0a/";
    http.content_type;
    content:"application/octet-stream"; bsize:24;
    http.header_names;
    content:!"Referer|0d 0a|";
    reference:md5,26b21902548e3b821387c90d729bace6;
    classtype:command-and-control;
    sid:2024233; rev:7;
    metadata:affected_product Windows_XP_Vista_7_8_10_Server_32_64_Bit, attack_target Client_Endpoint, created_at 2017_04_21, deployment Perimeter, confidence Medium, signature_severity Major, tag c2, updated_at 2020_10_09, mitre_tactic_id TA0010, mitre_tactic_name Exfiltration, mitre_technique_id T1041, mitre_technique_name Exfiltration_Over_C2_Channel;
)