alert tls $HOME_NET any -> $EXTERNAL_NET any (msg:"ET MALWARE Observed Ursnif Domain in TLS SNI (higmon .cyou)"; flow:established,to_server; tls.sni; content:"higmon.cyou"; bsize:11; fast_pattern; reference:url,www.mandiant.com/resources/blog/rm3-ldr4-ursnif-banking-fraud; classtype:trojan-activity; sid:2039663; rev:2; metadata:attack_target Client_Endpoint, created_at 2022_11_02, deployment Perimeter, deprecation_reason Age, malware_family ursnif, confidence High, signature_severity Major, tag SSL_Malicious_Cert, tag Description_Generated_By_Proofpoint_Nexus, updated_at 2024_08_28, reviewed_at 2024_08_28, mitre_tactic_id TA0011, mitre_tactic_name Command_And_Control, mitre_technique_id T1071, mitre_technique_name Application_Layer_Protocol;)