alert tcp $EXTERNAL_NET any -> $SMTP_SERVERS 25 (msg:"ET MALWARE USPS Inbound SPAM"; flow:established,to_server; content:"Content-Disposition|3A| attachment|3b|"; nocase; content:"filename=|22|USPS_Document.zip"; nocase; classtype:trojan-activity; sid:2012276; rev:2; metadata:created_at 2011_02_03, signature_severity Major, updated_at 2019_07_26;)