alert tls $HOME_NET any -> $EXTERNAL_NET any (msg:"ET MALWARE Lumma Stealer Domain in TLS SNI (deckerh .cyou)"; flow:established,to_server; tls.sni; bsize:12; content:"deckerh.cyou"; fast_pattern; classtype:trojan-activity; sid:2071737; rev:1; metadata:affected_product Windows_XP_Vista_7_8_10_Server_32_64_Bit, attack_target Client_Endpoint, created_at 2026_08_21, deployment Perimeter, malware_family LummaStealer, performance_impact Low, confidence High, signature_severity Major, updated_at 2026_08_21;)