alert tls $HOME_NET any -> $EXTERNAL_NET any (msg:"ET MALWARE ASNAROK Domain in TLS SNI"; flow:established,to_server; tls.sni; content:"ragnarokfromasgard.com"; bsize:22; reference:url,news.sophos.com/en-us/2020/04/26/asnarok/; classtype:command-and-control; sid:2030034; rev:1; metadata:attack_target Networking_Equipment, created_at 2020_04_27, deployment Perimeter, performance_impact Low, confidence High, signature_severity Major, tag Description_Generated_By_Proofpoint_Nexus, updated_at 2020_04_27, mitre_tactic_id TA0011, mitre_tactic_name Command_And_Control, mitre_technique_id T1071, mitre_technique_name Application_Layer_Protocol;)