arXiv:2603.23269cs.CRcs.AI2026-03

针对大模型越狱攻击中冗余搜索问题,提出智能筛选敏感词元的高效测试框架。

Not All Tokens Are Created Equal: Query-Efficient Jailbreak Fuzzing for LLMs

  • 基于替代模型评估每个词元对拒绝行为的贡献,识别敏感区域
  • 在仅25次查询下仍提升20%-40%成功率,70%以上查询量减少
  • 适用于安全测试人员快速评估大模型漏洞,尤其适合资源受限场景

大型语言模型虽广泛应用,却易受越狱提示攻击而输出违规内容。现有方法通常将所有词元视为同等重要,忽视其对触发模型拒绝行为的差异化贡献,导致在查询受限情况下产生大量冗余搜索,降低攻击效率并阻碍全面漏洞评估。本文开展词元级拒绝行为分析,发现词元贡献高度不均而非均匀分布;同时观察到跨模型拒绝倾向具有强一致性,支持使用替代模型估计目标模型的词元贡献。据此提出TriageFuzz框架,融合替代模型与拒绝引导的进化策略,通过轻量评分器自适应加权候选提示,精准定位敏感词元区域。在六个开源模型及三个商用API上的实验表明,该方法以显著更低的查询成本实现相当甚至更高的攻击成功率:90%成功率下查询量减少超70%;极端限制下(仅25次查询)攻击成功率提升20%-40%。

原文摘要 · Abstract (English)

Large Language Models(LLMs) are widely deployed, yet are vulnerable to jailbreak prompts that elicit policy-violating outputs. Although prior studies have uncovered these risks, they typically treat all tokens as equally important during prompt mutation, overlooking the varying contributions of individual tokens to triggering model refusals. Consequently, these attacks introduce substantial redundant searching under query-constrained scenarios, reducing attack efficiency and hindering comprehensive vulnerability assessment. In this work, we conduct a token-level analysis of refusal behavior and observe that token contributions are highly skewed rather than uniform. Moreover, we find strong cross-model consistency in refusal tendencies, enabling the use of a surrogate model to estimate token-level contributions to the target model's refusals. Motivated by these findings, we propose TriageFuzz, a token-aware jailbreak fuzzing framework that adapts the fuzz testing approach with a series of customized designs. TriageFuzz leverages a surrogate model to estimate the contribution of individual tokens to refusal behaviors, enabling the identification of sensitive regions within the prompt. Furthermore, it incorporates a refusal-guided evolutionary strategy that adaptively weights candidate prompts with a lightweight scorer to steer the evolution toward bypassing safety constraints. Extensive experiments on six open-source LLMs and three commercial APIs demonstrate that TriageFuzz achieves comparable attack success rates (ASR) with significantly reduced query costs. Notably, it attains a 90% ASR with over 70% fewer queries compared to baselines. Even under an extremely restrictive budget of 25 queries, TriageFuzz outperforms existing methods, improving ASR by 20-40%.

越狱攻击安全测试高效探索词元分析

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