alert tls $HOME_NET any -> $EXTERNAL_NET any (msg:"ET INFO Proxy Service Domain in TLS SNI (proxyjet .io)"; flow:established,to_server; tls.sni; dotprefix; content:".proxyjet.io"; endswith; fast_pattern; reference:url,cloud.google.com/blog/topics/threat-intelligence/disrupting-largest-residential-proxy-network; classtype:misc-activity; sid:2068316; rev:1; metadata:attack_target Client_Endpoint, created_at 2026_03_18, deployment Perimeter, confidence High, signature_severity Informational, tag Residential_Proxy_Service, tag Description_Generated_By_Proofpoint_Nexus, tag VPN_Services, updated_at 2026_03_18, mitre_tactic_id TA0011, mitre_tactic_name Command_And_Control, mitre_technique_id T1572, mitre_technique_name Protocol_Tunneling;)