Eliciting Harmful Capabilities by Fine-Tuning On Safeguarded Outputs
Although state-of-the-art large language models employ output-level safety mechanisms, they may still inadvertently leak harmful knowledge through indirect prompting, enabling open-source models—after fine-tuning—to reconstruct hazardous capabilities, thereby posing ecosystem-level risks. This work presents the first systematic investigation of such cross-model capability transfer threats and introduces a three-stage elicitation attack framework: by crafting benign prompts that are semantically proximate to harmful tasks, adversaries can extract implicit hazardous information from safeguarded models and use it to fine-tune open-source counterparts. Experiments on dangerous chemical synthesis tasks demonstrate that this approach recovers approximately 40% of the performance gap between protected and unrestricted models, with attack efficacy significantly amplified by both the capability of the frontier model and the scale of fine-tuning data, thereby challenging the adequacy of current safety paradigms.