How Wrong Am I? - Studying Adversarial Examples and their Impact on Uncertainty in Gaussian Process Machine Learning Models.

Machine learning models are vulnerable to adversarial examples: minor, in many cases imperceptible, perturbations to classification inputs. Among other suspected causes, adversarial examples exploit ML models that offer no well-defined indication as to how well a particular prediction is supported by training data, yet are forced to confidently extrapolate predictions in areas of high entropy. In contrast, Bayesian ML models, such as Gaussian Processes (GP), inherently model the uncertainty accompanying a prediction in the well-studied framework of Bayesian Inference. This paper is first to explore adversarial examples and their impact on uncertainty estimates for Gaussian Processes. To this end, we first present three novel attacks on Gaussian Processes: GPJM and GPFGS exploit forward derivatives in GP latent functions, and Latent Space Approximation Networks mimic the latent space representation in unsupervised GP models to facilitate attacks. Further, we show that these new attacks compute adversarial examples that transfer to non-GP classification models, and vice versa. Finally, we show that GP uncertainty estimates not only differ between adversarial examples and benign data, but also between adversarial examples computed by different algorithms.