Methods, apparatuses and computer program products that implement embodiments of the present invention for protecting a computer network, include receiving, in a security server, alerts of multiple different types, indicative of potentially malicious activity in the network, that are detected by multiple different protection appliances deployed in the network. The alerts in the security server are correlated so as to identify a first alert of a first type from a first protection appliance in the network and a second alert of a second type, different from the first type from a second protection appliance in the network that are together indicative of a single attack on the network. Finally, a consolidated alert is issued responsively to the attack.