<p>Many machine learning algorithms lack a procedure for testing/validating the integrity of training data so that attacks on training data remain a simple but yet effective way to derail those algorithms—they can result in devastating consequences, particularly in security-sensitive systems. The difficulty in designing an effective testing procedure is that the distribution of the training data may change naturally with time. Thus, the question is how to distinguish a natural change in the distribution and a change due to adversary’s attack. This work offers a partial answer with a modification of the existing <i>conditional generative adversarial networks</i> (CGAN) framework, where a generative model aims not only to avoid detection by a discriminator but also to design a poisoning sample which will result in the largest prediction error if a classifier is trained on the data that includes the sample. Simultaneous training of the validating and generative models results in a procedure that detects corrupted data which is nearly as optimal as the poisoning sample. The modified CGAN framework is then specialized for support vector machines (SVMs) and general classification models.</p>