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.certs; content:"|30 09 06 03 55 04 06 13 02|YU|31|"; fast_pattern; tls.cert_subject; content:!"ST="; content:"O="; distance:0; pcre:"/^(?!GoDaddy)[A-Z][a-z]+\s[A-Z][a-z]+\s[A-Z]/Rs"; content:"CN="; distance:0; pcre:"/^[a-z]{5,}\.[a-z]{2}/R"; reference:url,sslbl.abuse.ch; classtype:domain-c2; sid:2022521; rev:4; metadata:attack_target Client_and_Server, created_at 2016_02_15, deployment Perimeter, performance_impact Low, confidence High, signature_severity Major, tag SSL_Malicious_Cert, updated_at 2024_04_05, mitre_tactic_id TA0011, mitre_tactic_name Command_And_Control, mitre_technique_id T1071, mitre_technique_name Application_Layer_Protocol;)