alert tls $EXTERNAL_NET any -> $HOME_NET any (msg:"ET MALWARE FAKE YAHOO SSL Cert APT1"; flow:established,to_client; tls.cert_serial; content:"0A:38:C9:27:08:6F:96:4B:BE:75:DC:9F:C0:1A:C6:28"; tls.cert_subject; content:"CN=mail.yahoo.com"; reference:url,www.mandiant.com/apt1; classtype:targeted-activity; sid:2016470; 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_21;)