alert tls $EXTERNAL_NET any -> $HOME_NET any (msg:"ET INFO Usable Privacy DNS Over HTTPS Certificate Inbound"; flow:established,to_client; tls.cert_subject; content:"CN=adfree.usableprivacy.net"; bsize:27; fast_pattern; threshold:type both, count 1, seconds 600, track by_src; classtype:misc-activity; sid:2039556; rev:1; metadata:attack_target Client_Endpoint, created_at 2022_10_25, deployment Perimeter, confidence High, signature_severity Informational, tag DoH, tag Description_Generated_By_Proofpoint_Nexus, updated_at 2022_10_25, reviewed_at 2024_10_08;)