The rule "Web Server Suspicious User Agent Requests" is designed to identify unusual spikes in web server traffic that originate from suspicious user-agent strings commonly associated with reconnaissance tools. Such spikes can indicate potential scanning activities by attackers attempting to probe for vulnerabilities in web applications or servers. The rule focuses on various HTTP logs from different server types (Nginx, Apache, etc.) and checks for known malicious user-agent patterns typically used in vulnerability assessment tools, leading to detection and appropriate response measures. The rule also provides a framework for investigation, helping analysts differentiate between legitimate traffic and potential reconnaissance attempts, while offering triage steps for incident response. False positives such as approved vulnerability scanning may be present, hence a careful analysis of traffic is encouraged before taking action.