alert tls $HOME_NET any -> $EXTERNAL_NET any (msg:"ET MALWARE Observed TA444 Domain (systemupdate .store in TLS SNI)"; flow:established,to_server; tls.sni; bsize:18; content:"systemupdate.store"; fast_pattern; reference:url,twitter.com/tiresearch1/status/1701155845608964391; classtype:trojan-activity; sid:2048031; rev:2; metadata:attack_target Client_Endpoint, created_at 2023_09_11, deployment Perimeter, confidence High, signature_severity Major, tag Description_Generated_By_Proofpoint_Nexus, updated_at 2023_10_16, reviewed_at 2023_10_16, mitre_tactic_id TA0011, mitre_tactic_name Command_And_Control, mitre_technique_id T1071, mitre_technique_name Application_Layer_Protocol;)