alert tcp $EXTERNAL_NET any -> $SMTP_SERVERS 25 (msg:"ET MALWARE Asprox phishing email detected"; flow:established,to_server; content:"From|3a20|"; depth:6; content:"|0d0a|Bcc|3a20|"; within:150; flowbits:isset,ET.asproxmessageid; reference:url,www.secureworks.com/research/threats/danmecasprox; classtype:trojan-activity; sid:2008222; rev:5; metadata:attack_target Client_Endpoint, created_at 2010_07_30, deployment Perimeter, signature_severity Major, tag Phishing, updated_at 2019_07_26;)