Recent researches show that deep learning model is susceptible to backdoor attacks where the backdoor embedded in the model will be triggered when a backdoor instance arrives . In this paper, a novel backdoor detection method based on adversarial examples is proposed. The proposed method leverages intentional adversarial perturbations to detect whether the image contains a trigger, which can be applied in two scenarios (sanitize the training set in training stage and detect the backdoor instances in inference stage). Specifically, given an untrusted image, the adversarial perturbation is added to the input image intentionally, if the prediction of  model on the perturbed image is consistent with that on the unperturbed image, the input image will be considered as a backdoor instance. The proposed adversarial perturbation based method requires low computational resources and maintains the visual quality of the images. Experimental results show that, the  proposed defense method reduces the backdoor attack success rates from 99.47\%, 99.77\% and 97.89\% to 0.37\%, 0.24\% and 0.09\% on Fashion-MNIST, CIFAR-10 and GTSRB datasets, respectively. Besides, the proposed method maintains the visual quality of the image as the added perturbation is very small. In addition, for attacks under different settings (trigger transparency, trigger size and trigger pattern), the false acceptance rates of the proposed method are as low as 1.2\%, 0.3\% and 0.04\% on Fashion-MNIST, CIFAR-10 and GTSRB datasets, respectively , which demonstrates that the proposed method can achieve high defense performance against backdoor attacks under different attack settings  .
Recent researches show that deep learning model is susceptible to backdoor attacks . Many defenses against backdoor attacks have been proposed. However, existing defense works require high computational overhead or backdoor attack information such as the trigger size, which is difficult to satisfy in realistic scenarios . In this paper, a novel backdoor detection method based on adversarial examples is proposed. The proposed method leverages intentional adversarial perturbations to detect whether an image contains a trigger, which can be applied in both the training stage and the inference stage (sanitize the training set in training stage and detect the backdoor instances in inference stage). Specifically, given an untrusted image, the adversarial perturbation is added to the image intentionally. If the prediction of the model on the perturbed image is consistent with that on the unperturbed image, the input image will be considered as a backdoor instance. Compared with most existing defense works, the proposed adversarial perturbation based method requires low computational resources and maintains the visual quality of the images. Experimental results show that, the backdoor detection rate of the proposed defense method is 99.63\%, 99.76\% and 99.91\% on Fashion-MNIST, CIFAR-10 and GTSRB datasets, respectively. Besides, the proposed method maintains the visual quality of the image as the l2 norm of the added perturbation are as low as 2.8715, 3.0513 and 2.4362 on Fashion-MNIST, CIFAR-10 and GTSRB datasets, respectively . In addition, it is also demonstrated that the proposed method can achieve high defense performance against backdoor attacks under different attack settings (trigger transparency, trigger size and trigger pattern). Compared with the existing defense work (STRIP), the proposed method has better detection performance on all the three datasets, and is more efficient than STRIP .
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