alert tls $HOME_NET any -> $EXTERNAL_NET any (msg:"ET MALWARE Observed IcedID CnC Domain in TLS SNI"; flow:established,to_server; tls.sni; content:"circleoccupy.best"; bsize:17; classtype:domain-c2; sid:2030566; rev:1; metadata:affected_product Windows_XP_Vista_7_8_10_Server_32_64_Bit, attack_target Client_Endpoint, created_at 2020_07_21, deployment Perimeter, malware_family IcedID, performance_impact Low, confidence High, signature_severity Major, tag SSL_Malicious_Cert, tag Description_Generated_By_Proofpoint_Nexus, updated_at 2020_07_21, mitre_tactic_id TA0011, mitre_tactic_name Command_And_Control, mitre_technique_id T1071, mitre_technique_name Application_Layer_Protocol;)