arXiv:2604.07754cs.CRcs.CL2026-04ACL

研究微调方法如何让大模型失准,又如何修复,揭示攻防不对称性。

The Art of (Mis)alignment: How Fine-Tuning Methods Effectively Misalign and Realign LLMs in Post-Training

  • 对比6种微调方法,发现攻击时用ORPO最有效,防御时用DPO更优。
  • DPO虽能重对齐模型,但会降低模型实用性,存在权衡。
  • 发现模型有抗攻击差异,多轮攻击留有残余影响,适合安全研究者参考。

大语言模型部署面临重大伦理与安全挑战。尽管已有对齐技术提升模型安全性,但攻击者可利用这些技术造成模型失准(即‘误对齐’),并将其发布于公开平台以扩大危害。因此,在部署第三方未信任模型前,需进行额外的安全对齐(称为‘再对齐’)。本研究探讨了微调方法在误对齐、再对齐及其相互作用中的效果。通过在四个主流安全对齐的LLM上评估四种监督微调(SFT)和两种偏好微调(PFT)方法,我们发现攻击与防御之间存在机制不对称:奇数比值偏好优化(ORPO)在误对齐中最为有效,而直接偏好优化(DPO)在再对齐中表现最佳,但代价是模型实用性下降。此外,我们识别出模型特异性抗性、多轮对抗动态的残留效应等关键发现。这些结果强调了构建鲁棒防护机制和定制化安全对齐策略的重要性。代码已开源:https://github.com/zhangrui4041/The-Art-of-Mis-alignment。

原文摘要 · Abstract (English)

The deployment of large language models (LLMs) raises significant ethical and safety concerns. While LLM alignment techniques are adopted to improve model safety and trustworthiness, adversaries can exploit these techniques to undermine safety for malicious purposes, resulting in \emph{misalignment}. Misaligned LLMs may be published on open platforms to magnify harm. To address this, additional safety alignment, referred to as \emph{realignment}, is necessary before deploying untrusted third-party LLMs. This study explores the efficacy of fine-tuning methods in terms of misalignment, realignment, and the effects of their interplay. By evaluating four Supervised Fine-Tuning (SFT) and two Preference Fine-Tuning (PFT) methods across four popular safety-aligned LLMs, we reveal a mechanism asymmetry between attack and defense. While Odds Ratio Preference Optimization (ORPO) is most effective for misalignment, Direct Preference Optimization (DPO) excels in realignment, albeit at the expense of model utility. Additionally, we identify model-specific resistance, residual effects of multi-round adversarial dynamics, and other noteworthy findings. These findings highlight the need for robust safeguards and customized safety alignment strategies to mitigate potential risks in the deployment of LLMs. Our code is available at https://github.com/zhangrui4041/The-Art-of-Mis-alignment.

大模型安全对齐研究微调方法

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