ET INFO AhaDNS DNS Over HTTPS Certificate Inbound

Query · suricata

flow:established,to_client;
tls.cert_subject;
content:"ahadns.net"; fast_pattern;
pcre:"/CN=(?:[^\r\n]+?\.)?doh\x2e\w{2}\x2eahadns\.net(?!\.)/";
threshold:type both, count 1, seconds 600, track by_src;
Raw source ET INFO AhaDNS DNS Over HTTPS Certificate Inbound · Suricata
Esc
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 AhaDNS DNS Over HTTPS Certificate Inbound";
    flow:established,to_client;
    tls.cert_subject;
    content:"ahadns.net"; fast_pattern;
    pcre:"/CN=(?:[^\r\n]+?\.)?doh\x2e\w{2}\x2eahadns\.net(?!\.)/";
    threshold:type both, count 1, seconds 600, track by_src;
    reference:url,github.com/curl/curl/wiki/DNS-over-HTTPS;
    classtype:misc-activity;
    sid:2039433; rev:1;
    metadata:attack_target Client_Endpoint, created_at 2022_10_18, deployment Perimeter, confidence High, signature_severity Informational, tag DoH, tag Description_Generated_By_Proofpoint_Nexus, updated_at 2022_10_18;
)

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