An Embarrassingly Simple Defense Against LLM Abliteration Attacks
Authors: name: Harethah Abu Shairah; name: Hasan Abed Al Kader Hammoud; name: Bernard Ghanem; name: George Turkiyyah
Published: 2025-05-25 09:18:24

Abstract: Large language models (LLMs) are typically aligned to comply with safety
guidelines by refusing harmful instructions. A recent attack, termed
abliteration, isolates and suppresses the single latent direction most
responsible for refusal behavior, enabling the model to generate unethical
content. We propose a defense that modifies how models generate refusals. We
construct an extended-refusal dataset that contains harmful prompts with a full
response that justifies the reason for refusal. We then fine-tune
Llama-2-7B-Chat and Qwen2.5-Instruct (1.5B and 3B parameters) on our
extended-refusal dataset, and evaluate the resulting systems on a set of
harmful prompts. In our experiments, extended-refusal models maintain high
refusal rates, dropping at most by 10%, whereas baseline models' refusal rates
drop by 70-80% after abliteration. A broad evaluation of safety and utility
shows that extended-refusal fine-tuning neutralizes the abliteration attack
while preserving general performance.