alert tls $HOME_NET any -> $EXTERNAL_NET any (msg:"ET MALWARE Observed TA406 Related Domain in TLS SNI"; flow:established,to_server; tls.sni; bsize:15; content:"downwarding.com"; fast_pattern; reference:md5,d2ed41719424bb024535afa1b2d17f3a; classtype:domain-c2; sid:2048040; rev:1; metadata:attack_target Client_Endpoint, created_at 2023_09_12, deployment Perimeter, performance_impact Low, confidence Medium, signature_severity Major, tag SSL_Malicious_Cert, tag Description_Generated_By_Proofpoint_Nexus, updated_at 2023_09_12, reviewed_at 2024_04_15, mitre_tactic_id TA0011, mitre_tactic_name Command_And_Control, mitre_technique_id T1071, mitre_technique_name Application_Layer_Protocol;)