There is provided a method comprising: detecting a new process start at a network node of a computer network; determining that said process requires external code modules; observing the times at which one or more external code modules required by the new process are loaded relative to the process starting time; determining that the usage of an external code module required by the new process is anomalous when the time elapsed between the start of the process and loading of said external code module lies outside predetermined expected boundaries; and taking further action to protect the network node and/or the computer network based on determining that the usage of the external code module required by the detected new process is anomalous.