Despite the promise of Federated Learning (FL) for privacy-preserving model training on distributed data, it remains susceptible to backdoor attacks. These attacks manipulate models by embedding triggers (specific input patterns) in the training data, forcing misclassification as predefined classes during deployment. Traditional single-trigger attacks and recent work on cooperative multiple-trigger attacks, where clients collaborate, highlight limitations in attack realism due to coordination requirements. We investigate a more alarming scenario: non-cooperative multiple-trigger attacks. Here, independent adversaries introduce distinct triggers targeting unique classes. These parallel attacks exploit FL's decentralized nature, making detection difficult. Our experiments demonstrate the alarming vulnerability of FL to such attacks, where individual backdoors can be successfully learned without impacting the main task. This research emphasizes the critical need for robust defenses against diverse backdoor attacks in the evolving FL landscape. While our focus is on empirical analysis, we believe it can guide backdoor research toward more realistic settings, highlighting the crucial role of FL in building robust defenses against diverse backdoor threats. The code is available at \url{https://anonymous.4open.science/r/nba-980F/}.

随着Federated Learning（FL）在分布式数据上进行隐私保护模型训练的潜力，但它仍然容易受到后门攻击的影响。本研究探讨了FL面临的一种更令人担忧的情况：非合作的多触发器攻击。这些并行攻击利用了FL的去中心化特性，使得检测变得困难。实验结果显示了FL对此类攻击的显著脆弱性，即使影响主任务，也可以成功学习到单独的后门。该研究强调在不断发展的FL领域中，需要对各种后门攻击进行强大的防御。

联合学习中的非合作后门攻击：新的威胁景观