ET MALWARE Observed Malicious SSL Cert (Malicious Browser Ext CnC)

alert tls $EXTERNAL_NET any -> $HOME_NET any (
    msg:"ET MALWARE Observed Malicious SSL Cert (Malicious Browser Ext CnC)";
    flow:established,to_client;
    tls.cert_subject;
    content:"CN=*.dealctr.com"; bsize:16; fast_pattern;
    tls.cert_issuer;
    content:"C=US, O=Let's Encrypt, CN=Let's Encrypt Authority X3"; bsize:52;
    reference:url,darkreader.org/blog/attention/;
    reference:url,github.com/rainyrainyday/HomebrewOverlay;
    classtype:domain-c2;
    sid:2029921; rev:1;
    metadata:affected_product Web_Browsers, attack_target Client_and_Server, created_at 2020_04_15, deployment Perimeter, performance_impact Low, confidence High, signature_severity Major, tag SSL_Malicious_Cert, tag Description_Generated_By_Proofpoint_Nexus, updated_at 2020_04_15, mitre_tactic_id TA0011, mitre_tactic_name Command_And_Control, mitre_technique_id T1071, mitre_technique_name Application_Layer_Protocol;
)