alert tls $HOME_NET any -> $EXTERNAL_NET any (msg:"ET INFO Observed Microsoft Dev Tunnels Domain (devtunnels .ms in TLS SNI)"; flow:established,to_server; tls.sni; dotprefix; content:".devtunnels.ms"; endswith; fast_pattern; reference:url,learn.microsoft.com/en-us/azure/developer/dev-tunnels/security#domains; classtype:misc-activity; sid:2069122; rev:1; metadata:affected_product Any, attack_target Client_and_Server, created_at 2026_05_04, deployment Perimeter, performance_impact Low, confidence High, signature_severity Informational, tag Remote_Access, tag Network_Tunneling, updated_at 2026_05_04, mitre_tactic_id TA0011, mitre_tactic_name Command_And_Control, mitre_technique_id T1219, mitre_technique_name Remote_Access_Software;)