A combination of more frequent and less frequent security monitoring may be used to defeat worm or virus attacks. At periodic intervals, a risk assessment scan may be implemented to determine whether or not a worm attack has occurred. Prior thereto, an intermediate detection by an anomaly detection agent may determine whether or not a worm attack may have occurred. If a potential worm attack may have occurred, intermediate action, such as throttling of traffic, may occur. Then, at the next risk assessment scan, a determination may be made as to whether the attack is actually occurring and, if so, more effective and performance altering techniques may be utilized to counter the attack.