ET MALWARE Observed Malicious SSL Cert (MINEBRIDGE/MINEDOOR CnC)

alert tls $EXTERNAL_NET any -> $HOME_NET any (
    msg:"ET MALWARE Observed Malicious SSL Cert (MINEBRIDGE/MINEDOOR CnC)";
    flow:from_server,established;
    tls.cert_subject;
    content:"CN=conversia91.top"; nocase; fast_pattern; endswith;
    tls.cert_issuer;
    content:"C=US, O=Let's Encrypt, CN=Let's Encrypt Authority X3";
    reference:url,www.fireeye.com/blog/threat-research/2020/01/stomp-2-dis-brilliance-in-the-visual-basics.html;
    classtype:domain-c2;
    sid:2029388; rev:3;
    metadata:attack_target Client_and_Server, created_at 2020_02_06, deployment Perimeter, malware_family MINEBRIDGE, malware_family MINEDOOR, performance_impact Low, confidence High, signature_severity Major, tag SSL_Malicious_Cert, tag Description_Generated_By_Proofpoint_Nexus, updated_at 2020_10_28, mitre_tactic_id TA0011, mitre_tactic_name Command_And_Control, mitre_technique_id T1071, mitre_technique_name Application_Layer_Protocol;
)