alert tls $HOME_NET any -> $EXTERNAL_NET any (msg:"ET MALWARE TA446 Domain in TLS SNI (transfer-dns .com)"; flow:established,to_server; tls.sni; bsize:16; content:"transfer-dns.com"; fast_pattern; reference:url,github.com/Insikt-Group/Research/blob/master/BlueCharlie%2C%20Previously%20Tracked%20as%20TAG-53%2C%20Continues%20to%20Deploy%20New%20Infrastructure%20in%202023/BlueCharlie%2C%20Previously%20Tracked%20as%20TAG-53%2C%20Continues%20to%20Deploy%20New%20Infrastructure%20in%202023.csv; classtype:trojan-activity; sid:2047276; rev:2; metadata:attack_target Client_Endpoint, created_at 2023_08_09, deployment Perimeter, deprecation_reason Age, performance_impact Low, confidence High, signature_severity Major, tag TA446, tag Description_Generated_By_Proofpoint_Nexus, updated_at 2023_09_14, reviewed_at 2023_09_14, mitre_tactic_id TA0011, mitre_tactic_name Command_And_Control, mitre_technique_id T1071, mitre_technique_name Application_Layer_Protocol;)