alert tls $EXTERNAL_NET any -> $HOME_NET any (msg:"ET MALWARE ABUSE.CH SSL Blacklist Malicious SSL certificate detected (Dridex/Trickbot CnC)"; flow:established,to_client; tls.cert_serial; content:"00:"; startswith; tls.cert_subject; content:"O=Global Security"; fast_pattern; content:"OU=IT Department"; content:"example."; distance:0; reference:url,sslbl.abuse.ch; classtype:domain-c2; sid:2021013; rev:8; metadata:attack_target Client_and_Server, created_at 2015_04_27, deployment Perimeter, deprecation_reason False_Positive, malware_family TrickBot, malware_family Dridex, performance_impact Low, confidence High, signature_severity Major, tag SSL_Malicious_Cert, updated_at 2024_04_09, mitre_tactic_id TA0011, mitre_tactic_name Command_And_Control, mitre_technique_id T1071, mitre_technique_name Application_Layer_Protocol;)