alert tls $HOME_NET any -> $EXTERNAL_NET any (msg:"ET MALWARE Observed Ducktail Malware Related Domain in TLS SNI (ductai .xyz)"; flow:established,to_server; tls.sni; dotprefix; content:".ductai.xyz"; endswith; fast_pattern; reference:md5,bdab780d4cfc976a87cc13c4f4db7253; reference:md5,dd839a9c131edba4718cea2d467f34a7; classtype:domain-c2; sid:2048258; rev:2; metadata:attack_target Client_Endpoint, created_at 2023_09_26, deployment Perimeter, deprecation_reason Age, performance_impact Low, confidence High, signature_severity Major, tag SSL_Malicious_Cert, tag Description_Generated_By_Proofpoint_Nexus, updated_at 2024_04_29, reviewed_at 2024_04_29, mitre_tactic_id TA0011, mitre_tactic_name Command_And_Control, mitre_technique_id T1071, mitre_technique_name Application_Layer_Protocol; target:src_ip;)