From webshell weak signals to meaningful alert in four steps

This post explains a practical method to detect webshell activity by correlating weak network signals (Palo Alto "Vulnerability" alerts) with endpoint indicators (script/file modifications in web-accessible directories). It covers webshell basics, limitations of network-only alerts, and demonstrates how to combine SIEM, firewall alerts, and EDR watchlists (e.g., Carbon Black) to create higher-fidelity, actionable detections.