An intrusion detection system for detecting intrusion events in a computer network and assessing the vulnerability of the network components to the detected events. The intrusion detection system comprises a scanner, one or more sensors and a security console for operation within a networked computing environment. A sensor of the inventive intrusion detection system can monitor the networked computing environment for possible intrusion events representing an unauthorized access or use of the network resources. In response to detecting an intrusion event, the sensor can generate a scan request for handling by a scanner. This request initiates a scan of the target computer by the scanner to determine the vulnerability of the target to the attack. Based on this vulnerability analysis, the inventive intrusion detection system can evaluate the severity of the detected intrusion event and issue an alert having a priority corresponding to the severity of the intrusion.