  Large language models (LLMs) show inherent brittleness in their safety
mechanisms, as evidenced by their susceptibility to jailbreaking and even
non-malicious fine-tuning. This study explores this brittleness of safety
alignment by leveraging pruning and low-rank modifications. We develop methods
to identify critical regions that are vital for safety guardrails, and that are
disentangled from utility-relevant regions at both the neuron and rank levels.
Surprisingly, the isolated regions we find are sparse, comprising about $3\%$
at the parameter level and $2.5\%$ at the rank level. Removing these regions
compromises safety without significantly impacting utility, corroborating the
inherent brittleness of the model's safety mechanisms. Moreover, we show that
LLMs remain vulnerable to low-cost fine-tuning attacks even when modifications
to the safety-critical regions are restricted. These findings underscore the
urgent need for more robust safety strategies in LLMs.
