Title: STRATA: Simple, Gradient-free Attacks for Models of Code. Abstract: Adversarial examples are imperceptible perturbations in the input to a neural model that result in misclassification. Generating adversarial examples for source code poses an additional challenge compared to the domains of images and natural language, because source code perturbations must adhere to strict semantic guidelines so the resulting programs retain the functional meaning of the code. We propose a simple and efficient gradient-free method for generating state-of-the-art adversarial examples on models of code that can be applied in a white-box or black-box setting. Our method generates untargeted and targeted attacks, and empirically outperforms competing gradient-based methods with less information and less computational effort.