An apparatus, a computer program product and a method for dimensionality reduction comprising: obtaining a set of Application Programming Interface (API) functions of a system invocable by a program, and a set of artifacts. Each artifact is associated with at least one API function and indicative of a functionality thereof. The method further comprising: clustering the API functions based on an analysis of the artifacts to create a set of clusters smaller than the set of API functions, such that each cluster comprises API functions having a similar functionality; and performing a dimensionality reduction to a feature vector using the set of clusters.