alert tls $EXTERNAL_NET any -> $HOME_NET any (msg:"ET INFO URL Shortener (s .yam .com) in TLS SNI"; flow:established,to_client; tls.cert_subject; content:"s.yam.com"; fast_pattern; pcre:"/CN=(?:[^\r\n]+?\.)?s\.yam\.com(?!\.)/"; classtype:misc-activity; sid:2045632; rev:1; metadata:attack_target Client_Endpoint, created_at 2023_05_10, deployment Perimeter, confidence High, signature_severity Informational, tag Description_Generated_By_Proofpoint_Nexus, updated_at 2023_05_10;)