An Empirical Evaluation of the Usefulness of Word Embedding Techniques in Deep Learning-Based Vulnerability Prediction

Abstract

Software security is a critical consideration for software development companies that want to provide their customers with high-quality and dependable software. The automated detection of software vulnerabilities is a critical aspect in software security. Vulnerability prediction is a mechanism that enables the detection and mitigation of software vulnerabilities early enough in the development cycle. Recently the scientific community has dedicated a lot of effort on the design of Deep learning models based on text mining techniques. Initially, Bag-of-Words was the most promising method but recently more complex models have been proposed focusing on the sequences of instructions in the source code. Recent research endeavors have started utilizing word embedding vectors, which are widely used in text classification tasks like semantic analysis, for representing the words (i.e., code instructions) in vector format. These vectors could be trained either jointly with the other layers of the neural network, or they can be pre-trained using popular algorithms like word2vec and fast-text. In this paper, we empirically examine whether the utilization of word embedding vectors that are pre-trained separately from the vulnerability predictor could lead to more accurate vulnerability prediction models. For the purposes of the present study, a popular vulnerability dataset maintained by NIST was utilized. The results of the analysis suggest that pre-training the embedding vectors separately from the neural network leads to better vulnerability predictors with respect to their effectiveness and performance.