alert tls $EXTERNAL_NET any -> $HOME_NET any (msg:"ET MALWARE SERVER SSL Cert APT1"; flow:established,to_client; tls.cert_serial; content:"52:55:38:16:FB:0D:1A:8A:4B:45:04:CB:06:BC:C4:AF"; tls.cert_subject; content:"CN=SERVER"; reference:url,www.mandiant.com/apt1; classtype:targeted-activity; sid:2016467; 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_24;)