A number of critical monitoring and decision systems make decisions based on image, video, audio, voice commands, and other sensor inputs. The decisions nowadays are often made by Artificial Intelligence (AI) systems with complex algorithms such as those based on deep neural networks (DNNs), which have achieved state-of-the-art performance in computer vision, speech recognition, and other areas. However, AI-based algorithms, such as DNNs, have been shown to be easily fooled by adversarial perturbations which slightly modify a legitimate input (such as image or voice) in a specific direction and are perceptually indistinguishable from the original. This presents a significant security risk for the aforementioned systems. This project tackles the problem of detecting such "forgeries" by constructing detectors based on fundamental theories of statistical inference, that are well suited to detecting weak signal perturbations. The general approach is closely related to steganalysis (detection of secret patterns embedded in cover signals).