alert http $EXTERNAL_NET any -> any any (msg:"ET MALWARE Possible PHP.MAILER WebShell Register Shutdown Function Request Inbound"; flow:established,to_server; http.method; content:"POST"; http.uri; content:".php"; endswith; http.request_body; content:"r=register_shutdown_function"; startswith; fast_pattern; content:"&d="; distance:0; content:"&s="; distance:0; content:"&c="; distance:0; reference:url,blog.trendmicro.com/trendlabs-security-intelligence/spam-campaign-abuses-php-functions-for-persistence-uses-compromised-devices-for-evasion-and-intrusion/; classtype:trojan-activity; sid:2027970; rev:3; metadata:attack_target Server, created_at 2019_09_09, deployment Perimeter, performance_impact Low, confidence Medium, signature_severity Major, updated_at 2020_09_17;)