alert tls $EXTERNAL_NET any -> $HOME_NET any (msg:"ET MALWARE Observed Malicious SSL/TLS Certificate (SilentLibrarian)"; flow:from_server,established; tls.cert_subject; content:"CN=logon.bradley.zedu.me"; fast_pattern; classtype:domain-c2; sid:2037823; rev:2; metadata:attack_target Client_and_Server, created_at 2022_07_26, deployment Perimeter, malware_family SilentLibrarian, performance_impact Low, confidence High, signature_severity Major, tag SSL_Malicious_Cert, tag Description_Generated_By_Proofpoint_Nexus, updated_at 2023_03_13, mitre_tactic_id TA0042, mitre_tactic_name Resource_Development, mitre_technique_id T1587, mitre_technique_name Develop_Capabilities;)