alert tls $HOME_NET any -> $EXTERNAL_NET any (msg:"ET INFO Observed Network Tunneling Service Domain (tunnl .gg) in TLS SNI"; flow:established,to_server; tls.sni; dotprefix; content:".tunnl.gg"; endswith; fast_pattern; reference:url,tunnl.gg; classtype:misc-activity; sid:2066010; rev:1; metadata:affected_product Any, attack_target Client_and_Server, created_at 2025_12_04, deployment Perimeter, performance_impact Low, confidence High, signature_severity Informational, tag Network_Tunneling, updated_at 2025_12_04, mitre_tactic_id TA0011, mitre_tactic_name Command_And_Control, mitre_technique_id T1572, mitre_technique_name Protocol_Tunneling;)