BehaviorGuard: Online Backdoor Defense for Deep Reinforcement Learning

Fuente: arXiv
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Hauptverfasser: Yu, Yinbo, Yin, Xueyu, Wang, Jiadai, Tian, Chunwei, Xu, Sai, Zhu, Qi, Zhang, Daoqiang
Format: Preprint
Veröffentlicht: 2026
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author Yu, Yinbo
Yin, Xueyu
Wang, Jiadai
Tian, Chunwei
Xu, Sai
Zhu, Qi
Zhang, Daoqiang
author_facet Yu, Yinbo
Yin, Xueyu
Wang, Jiadai
Tian, Chunwei
Xu, Sai
Zhu, Qi
Zhang, Daoqiang
contents Backdoor attacks pose a serious threat to deep reinforcement learning (DRL). Current defenses typically rely on reward anomalies to reverse-engineer triggers and model finetuning to remove backdoors. However, complex trigger patterns undermine their robustness, and fine-tuning entails high costs, limiting practical utility. Therefore, we shift defense concerns to trigger-agnostic backdoor output behaviors and propose BehaviorGuard, an online behavior-based backdoor detection and mitigation framework for DRL. Specifically, we find that regardless of attacks, backdoored policies induce consistent shifts in action distributions to ensure reliable activation, leaving detectable traces in high-quantile regions and distribution tails, even in the absence of triggers. Based on this, we design a novel metric that captures behavioral drift in action distributions to identify and suppress backdoor actions at runtime. To our knowledge, this is the first online backdoor defense that counters attacks both in single- and multi-agent DRL. Evaluated across diverse benchmarks with different backdoor attacks, BehaviorGuard consistently surpasses prior methods in both efficacy and efficiency.
format Preprint
id arxiv_https___arxiv_org_abs_2605_05977
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle BehaviorGuard: Online Backdoor Defense for Deep Reinforcement Learning
Yu, Yinbo
Yin, Xueyu
Wang, Jiadai
Tian, Chunwei
Xu, Sai
Zhu, Qi
Zhang, Daoqiang
Artificial Intelligence
Backdoor attacks pose a serious threat to deep reinforcement learning (DRL). Current defenses typically rely on reward anomalies to reverse-engineer triggers and model finetuning to remove backdoors. However, complex trigger patterns undermine their robustness, and fine-tuning entails high costs, limiting practical utility. Therefore, we shift defense concerns to trigger-agnostic backdoor output behaviors and propose BehaviorGuard, an online behavior-based backdoor detection and mitigation framework for DRL. Specifically, we find that regardless of attacks, backdoored policies induce consistent shifts in action distributions to ensure reliable activation, leaving detectable traces in high-quantile regions and distribution tails, even in the absence of triggers. Based on this, we design a novel metric that captures behavioral drift in action distributions to identify and suppress backdoor actions at runtime. To our knowledge, this is the first online backdoor defense that counters attacks both in single- and multi-agent DRL. Evaluated across diverse benchmarks with different backdoor attacks, BehaviorGuard consistently surpasses prior methods in both efficacy and efficiency.
title BehaviorGuard: Online Backdoor Defense for Deep Reinforcement Learning
topic Artificial Intelligence
url https://arxiv.org/abs/2605.05977