alert tls $EXTERNAL_NET any -> $HOME_NET any (
msg:"ET INFO DNS Over HTTPS Certificate Inbound (cnnic-chinatelecom-chinamobile-chinaunicom--bili-d .dahi .icu)";
flow:established,to_client;
tls.cert_subject;
content:"cnnic-chinatelecom-chinamobile-chinaunicom--bili-d.dahi.icu"; fast_pattern;
pcre:"/CN=(?:[^\r\n]+?\.)?cnnic\-chinatelecom\-chinamobile\-chinaunicom\-\-bili\-d\.dahi\.icu(?!\.)/";
reference:url,github.com/curl/curl/wiki/DNS-over-HTTPS;
classtype:misc-activity;
sid:2045823; rev:1;
metadata:attack_target Client_Endpoint, created_at 2023_05_23, deployment Perimeter, confidence High, signature_severity Informational, tag Description_Generated_By_Proofpoint_Nexus, updated_at 2023_05_23;
)