alert tls $EXTERNAL_NET any -> $HOME_NET any (msg:"ET MALWARE ABUSE.CH SSL Blacklist Malicious SSL certificate detected (Dridex)"; flow:established,to_client; tls.cert_subject; content:!"ST="; content:!"L="; content:"C=CH"; fast_pattern; pcre:"/O=(?!GoDaddy)[A-Z][a-z]+\s[A-Z][a-z]+\s(?:NL|Pty|Inc|Corp|Ltd)\.?,.+CN=[a-z]{5,}\.[a-z]{2,3}(?:$|,)/R"; reference:url,sslbl.abuse.ch; classtype:domain-c2; sid:2022279; rev:3; metadata:attack_target Client_and_Server, created_at 2015_12_18, deployment Perimeter, performance_impact Low, confidence High, signature_severity Major, tag SSL_Malicious_Cert, tag Description_Generated_By_Proofpoint_Nexus, updated_at 2022_03_14, 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;)