alert smtp $HOME_NET any -> $EXTERNAL_NET any (msg:"ET MALWARE Snake Keylogger Exfil via SMTP"; flow:established,to_server; content:"Subject|3a 20|"; content:"|20 7c 20|Snake Tracker|0d 0a|"; within:200; fast_pattern; reference:md5,b8eb18c7a33fec016ff3c1777f3819c2; classtype:trojan-activity; sid:2044767; rev:1; metadata:affected_product Windows_XP_Vista_7_8_10_Server_32_64_Bit, attack_target Client_Endpoint, created_at 2023_03_27, deployment Perimeter, malware_family Snake_Keylogger, performance_impact Low, confidence High, signature_severity Critical, tag Description_Generated_By_Proofpoint_Nexus, updated_at 2023_03_27; target:src_ip;)