alert http $HOME_NET any -> $EXTERNAL_NET any (msg:"ET RETIRED Win32/HackTool.Agent.CS SMTP Scanner CnC Checkin"; flow:established,to_server; http.method; content:"GET"; http.uri; content:"/ssa/scan.php"; fast_pattern; http.header_names; content:!"Referer"; classtype:trojan-activity; sid:2037754; rev:2; metadata:attack_target SMTP_Server, created_at 2022_07_13, deployment Perimeter, former_category MALWARE, malware_family Win32_HackTool_Agent_CS, performance_impact Low, confidence Medium, signature_severity Major, tag Description_Generated_By_Proofpoint_Nexus, updated_at 2024_09_17, reviewed_at 2024_09_17;)