Abstract: The techniques disclosed herein identify ransomware attacks as they are occurring, improving the security and functionality of computer systems. Ransomware attacks are identified using a new probabilistic machine learning model that better handles the unique properties of ransomware data. Ransomware data includes a list of computing operations, some of which are labeled as being associated with ransomware attacks. In contrast to deterministic machine learning techniques that learn weights, probabilistic machine learning techniques learn the parameters of a distribution function. In some configurations, a radial Spike and Slab distribution function is used within a Bayesian neural network framework to better handle sparse, missing, and imbalanced data. Once trained, the machine learning model may be provided with real-time operations, e.g., from a cloud service security module, from which to infer whether a ransomware attack is taking place.

Abstract: A method classifies missing labels. The method computes, using a neural network model trained on training data, rank-based statistics of a feature of a time series segment to attempt to select two candidate labels from the training data that the segment most likely belongs to. The method classifies the segment using k-NN-based classification applied to the training data, responsive to the two candidate labels being present in the training data. The method classifies the segment by hypothesis testing, responsive to only one candidate label being present in the training data. The method classifies the segment into a class with higher values of the rank-based statistics from among a plurality of classes with different values of the rank-based statistics, responsive to no candidate labels being present in the training data. The method corrects a prediction by an applicable one of the classifying steps by majority voting with time windows.