alert tls $HOME_NET any -> $EXTERNAL_NET any (msg:"ET INFO Observed URL Shortener Domain (url .rw in TLS SNI)"; flow:established,to_server; tls.sni; bsize:6; content:"url.rw"; fast_pattern; reference:url,url.rw/p/urlrw-vs-bitly; classtype:misc-activity; sid:2059280; rev:1; metadata:attack_target Client_Endpoint, created_at 2025_01_15, deployment Perimeter, performance_impact Low, confidence High, signature_severity Informational, tag Description_Generated_By_Proofpoint_Nexus, updated_at 2025_01_15, reviewed_at 2025_03_14;)