ET INFO Google DNS Over HTTPS Certificate Inbound

Query · suricata

flow:established,to_client;
threshold:type both, track by_src, count 1, seconds 300;
tls.cert_subject;
content:"CN=dns.google"; endswith; fast_pattern;
tls.cert_issuer;
content:"C=US, O=Google Trust Services";
target:src_ip;
Raw source ET INFO Google DNS Over HTTPS Certificate Inbound · Suricata
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Published by Emerging Threats Open ↗, licensed under BSD 3-Clause ↗. Line breaks added for readability; the rule is otherwise unchanged. 
alert tls $EXTERNAL_NET any -> $HOME_NET any (
    msg:"ET INFO Google DNS Over HTTPS Certificate Inbound";
    flow:established,to_client;
    threshold:type both, track by_src, count 1, seconds 300;
    tls.cert_subject;
    content:"CN=dns.google"; endswith; fast_pattern;
    tls.cert_issuer;
    content:"C=US, O=Google Trust Services";
    reference:url,developers.google.com/speed/public-dns/docs/doh/;
    reference:md5,206a146a84eb6c2cca82ac245615349a;
    reference:md5,8064d8e4bfa66d1b6f665faf1ddf46b2;
    classtype:misc-activity;
    sid:2049796; rev:5;
    metadata:affected_product Any, attack_target Client_Endpoint, created_at 2019_08_21, deployment Perimeter, performance_impact Low, confidence High, signature_severity Informational, tag DoH, updated_at 2023_12_20, reviewed_at 2024_04_22, former_sid 2838109;
    target:src_ip;
)

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