alert tls $EXTERNAL_NET any -> $HOME_NET any (msg:"ET INFO Keweon Center DNS Over HTTPS Certificate Inbound"; flow:established,to_client; tls.cert_subject; content:"CN=doh.asecdns.com"; fast_pattern; bsize:18; threshold:type both, count 1, seconds 600, track by_src; reference:url,serverinfo.keweon.center/; classtype:misc-activity; sid:2035157; rev:1; metadata:attack_target Client_Endpoint, created_at 2022_02_09, deployment Perimeter, performance_impact Low, confidence High, signature_severity Major, tag DoH, tag Description_Generated_By_Proofpoint_Nexus, updated_at 2022_02_09;)