alert tls $HOME_NET any -> $EXTERNAL_NET any (msg:"ET MALWARE Observed TONESHELL Domain (dl6yfsl .com in TLS SNI)"; flow:established,to_server; tls.sni; bsize:11; content:"dl6yfsl.com"; fast_pattern; reference:url,web-assets.esetstatic.com/wls/en/papers/white-papers/ceranakeeper.pdf; classtype:domain-c2; sid:2056422; rev:1; metadata:affected_product Windows_XP_Vista_7_8_10_Server_32_64_Bit, attack_target Client_Endpoint, created_at 2024_10_02, deployment Perimeter, malware_family CeranaKeeper, confidence High, signature_severity Major, tag Description_Generated_By_Proofpoint_Nexus, updated_at 2024_10_02, mitre_tactic_id TA0011, mitre_tactic_name Command_And_Control, mitre_technique_id T1071, mitre_technique_name Application_Layer_Protocol;)