ET MALWARE MSIL/Hidden-Tear Variant Ransomware CnC Checkin

alert http $HOME_NET any -> $EXTERNAL_NET any (
    msg:"ET MALWARE MSIL/Hidden-Tear Variant Ransomware CnC Checkin";
    flow:established,to_server;
    http.uri;
    content:".php?rid=ClsgIFVzZXItSUQgIF0gID"; fast_pattern;
    pcre:"/\.php\?rid=(?:[A-Za-z0-9+/]{4})*(?:[A-Za-z0-9+/]{2}==|[A-Za-z0-9+/]{3}=|[A-Za-z0-9+/]{4})$/i";
    http.header;
    content:"Ransom|3a 20|Client|0d 0a|";
    http.header_names;
    content:!"User-Agent|0d 0a|";
    content:!"Referer|0d 0a|";
    reference:md5,b991a99335b01bed8da4401fee1f2d45;
    classtype:command-and-control;
    sid:2024204; rev:3;
    metadata:affected_product Windows_XP_Vista_7_8_10_Server_32_64_Bit, attack_target Client_Endpoint, created_at 2017_04_12, deployment Perimeter, malware_family Ransomware, malware_family Hidden_Tear, confidence High, signature_severity Major, tag Ransomware, updated_at 2020_08_05, mitre_tactic_id TA0040, mitre_tactic_name Impact, mitre_technique_id T1486, mitre_technique_name Data_Encrypted_for_Impact;
)