通过分散拒绝信号,让大模型更难被恶意攻击破解。
An Embarrassingly Simple Defense Against LLM Abliteration Attacks
- 将拒绝理由拆解到多个词位置,避免单一信号被攻击
- 攻击后拒绝率下降不超过10%,远优于基准模型的70-80%下降
- 适合关注模型安全、对抗攻击防护的研究者与开发者
大型语言模型通常通过安全微调来拒绝有害指令。最近一种称为‘抹除攻击’(abliteration)的方法,识别并压制最能引发拒绝行为的单一潜在方向,从而诱导模型生成有害内容。本文提出一种防御策略,从根本上改变模型表达拒绝的方式:构建一个扩展拒绝数据集,其中对有害提示的回复在拒绝前提供详细理由,将拒绝信号分布到多个词元位置。在 Llama-2-7B-Chat 和 Qwen2.5-Instruct(1.5B 与 3B 参数)上使用该数据集进行微调,使模型在遭受抹除攻击时仍保持高拒绝率——拒绝率最多下降10%,而基线模型下降达70-80%。全面评估显示,扩展拒绝微调有效中和了抹除攻击,同时维持模型通用性能,并增强多种对齐场景下的鲁棒性。
原文摘要 · Abstract (English)
Large language models (LLMs) are typically aligned to refuse harmful instructions through safety fine-tuning. A recent attack, termed abliteration, identifies and suppresses the single latent direction most responsible for refusal behavior, thereby enabling models to generate harmful content. We propose a defense that fundamentally alters how models express refusal. We construct an extended-refusal dataset in which responses to harmful prompts provide detailed justifications before refusing, distributing the refusal signal across multiple token positions. Fine-tuning Llama-2-7B-Chat and Qwen2.5-Instruct (1.5B and 3B parameters) on this dataset yields models that maintain high refusal rates under abliteration: refusal rates drop by at most 10%, compared to 70-80% drops in baseline models. Comprehensive evaluations of safety and utility demonstrate that extended-refusal fine-tuning effectively neutralizes abliteration attacks while preserving general model performance and enhancing robustness across multiple alignment scenarios.
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