alert tls $EXTERNAL_NET any -> $HOME_NET any (msg:"ET MALWARE EMAIL SSL Cert APT1"; flow:established,to_client; tls.cert_serial; content:"2F:09:DD:E0:FF:81:B7:6C:BF:2F:17:92:0C:D8:BD:57"; tls.cert_subject; content:"CN=EMAIL"; reference:url,www.mandiant.com/apt1; classtype:targeted-activity; sid:2016464; rev:4; metadata:attack_target Client_Endpoint, created_at 2013_02_22, deployment Perimeter, confidence High, signature_severity Major, tag SSL_Malicious_Cert, updated_at 2022_03_18;)