alert tls $HOME_NET any -> $EXTERNAL_NET any (msg:"ET HUNTING TryCloudFlare Domain in TLS SNI"; flow:established,to_server; tls.sni; dotprefix; content:".trycloudflare.com"; endswith; reference:url,developers.cloudflare.com/cloudflare-one/connections/connect-networks/do-more-with-tunnels/trycloudflare/; reference:url,www.proofpoint.com/uk/blog/threat-insight/threat-actor-abuses-cloudflare-tunnels-deliver-rats; classtype:misc-activity; sid:2058175; rev:1; metadata:attack_target Client_and_Server, created_at 2024_12_10, deployment Perimeter, performance_impact Low, confidence High, signature_severity Major, tag Description_Generated_By_Proofpoint_Nexus, updated_at 2024_12_10;)