Deep neural networks are vulnerable to adversarial attacks, often leading to erroneous outputs. Adversarial training has been recognized as one of the most effective methods to counter such attacks. However, existing adversarial training techniques have predominantly been tested on balanced datasets, whereas real-world data often exhibit a long-tailed distribution, casting doubt on the efficacy of these methods in practical scenarios. In this paper, we delve into adversarial training under long-tailed distributions. Through an analysis of the previous work "RoBal", we discover that utilizing Balanced Softmax Loss alone can achieve performance comparable to the complete RoBal approach while significantly reducing training overheads. Additionally, we reveal that, similar to uniform distributions, adversarial training under long-tailed distributions also suffers from robust overfitting. To address this, we explore data augmentation as a solution and unexpectedly discover that, unlike results obtained with balanced data, data augmentation not only effectively alleviates robust overfitting but also significantly improves robustness. We further investigate the reasons behind the improvement of robustness through data augmentation and identify that it is attributable to the increased diversity of examples. Extensive experiments further corroborate that data augmentation alone can significantly improve robustness. Finally, building on these findings, we demonstrate that compared to RoBal, the combination of BSL and data augmentation leads to a +6.66% improvement in model robustness under AutoAttack on CIFAR-10-LT. Our code is available at https://github.com/NISPLab/AT-BSL .

深度神经网络在对抗攻击中易受攻击，现有的对抗训练方法在平衡数据集上表现良好，但实际情况中长尾分布的数据样本下该方法的有效性存疑。本文研究了长尾分布下的对抗训练，发现仅利用平衡Softmax损失函数可以在降低训练开销的同时达到与之前方法相当的性能；此外，通过数据增强技术，我们发现长尾分布下的对抗训练不仅可以减轻过拟合问题，而且可以显著提高鲁棒性；我们还发现增加训练样本的多样性是提高鲁棒性的原因。在CIFAR-10-LT上的AutoAttack中，与RoBal相比，平衡Softmax损失函数与数据增强的组合能够使模型的鲁棒性提高6.66%。

重温长尾分布下的对抗训练