alert tls $HOME_NET any -> $EXTERNAL_NET any (msg:"ET MALWARE Observed DarkSide Ransomware CnC Domain in TLS SNI"; flow:established,to_server; tls.sni; content:"securebestapp20.com"; bsize:19; fast_pattern; reference:md5,222792d2e75782516d653d5cccfcf33b; classtype:domain-c2; sid:2032958; rev:1; metadata:attack_target Client_Endpoint, created_at 2020_12_29, deployment Perimeter, malware_family DarkSide, confidence High, signature_severity Major, tag SSL_Malicious_Cert, tag Ransomware, tag Description_Generated_By_Proofpoint_Nexus, updated_at 2020_12_29, mitre_tactic_id TA0011, mitre_tactic_name Command_And_Control, mitre_technique_id T1071, mitre_technique_name Application_Layer_Protocol;)