ET MALWARE Buran Ransomware Activity M1

alert http $HOME_NET any -> $EXTERNAL_NET any (
    msg:"ET MALWARE Buran Ransomware Activity M1";
    flow:established,to_server;
    http.method;
    content:"GET";
    http.user_agent;
    content:"BURAN"; fast_pattern; bsize:5;
    http.referer;
    content:!".";
    pcre:"/^[a-f0-9]{8}-[a-f0-9]{4}-[a-f0-9]{4}-[a-f0-9]{4}-[a-f0-9]{12}$/i";
    http.header_names;
    content:!"Connection";
    content:!"Cache";
    content:!"Accept";
    classtype:trojan-activity;
    sid:2027446; rev:3;
    metadata:affected_product Windows_XP_Vista_7_8_10_Server_32_64_Bit, attack_target Client_Endpoint, created_at 2019_06_10, deployment Perimeter, malware_family Buran, confidence High, signature_severity Major, tag Ransomware, tag Description_Generated_By_Proofpoint_Nexus, updated_at 2020_08_31, mitre_tactic_id TA0040, mitre_tactic_name Impact, mitre_technique_id T1486, mitre_technique_name Data_Encrypted_for_Impact;
)