alert tls $HOME_NET any -> $EXTERNAL_NET any (msg:"ET INFO Observed Free Hosting Domain Domain (b4a .io in TLS SNI)"; flow:established,to_server; tls.sni; dotprefix; content:".b4a.io"; endswith; fast_pattern; reference:url,github.com/BadSamuraiDev/bs-lists/; classtype:misc-activity; sid:2068641; rev:1; metadata:affected_product Any, attack_target Client_and_Server, created_at 2026_04_08, deployment Perimeter, performance_impact Low, confidence High, signature_severity Informational, tag Free_Hosting, updated_at 2026_04_08, mitre_tactic_id TA0001, mitre_tactic_name Initial_Access, mitre_technique_id T1566, mitre_technique_name Phishing;)