alert tls $HOME_NET any -> $EXTERNAL_NET any (msg:"ET INFO Observed VNT VPN Domain (vnt .8443 .eu .org in TLS SNI)"; flow:established,to_server; tls.sni; bsize:15; content:"vnt.8443.eu.org"; fast_pattern; reference:url,rustvnt.com; reference:url,github.com/vnt-dev/vnt; classtype:misc-activity; sid:2065349; rev:1; metadata:attack_target Client_and_Server, created_at 2025_10_23, deployment Perimeter, confidence High, signature_severity Informational, tag Description_Generated_By_Proofpoint_Nexus, tag VNT, tag VPN, updated_at 2025_10_23, mitre_tactic_id TA0011, mitre_tactic_name Command_And_Control, mitre_technique_id T1572, mitre_technique_name Protocol_Tunneling;)