Summary
The authors investigate whether the jailbreaks that are effective in eliciting problematic responses from LLMs, also transfer to multimodal LLMs. To this end, the authors build upon an existing benchmark and expand it to include similar unsafe prompts (textual expansion), and various related/unrelated images (visual expansion), providing a multimodal benchmark comprising 28k examples. The authors find that the prompts that elicit unsafe responses from LLMs, also transfer to multimodal LLMs. Furthermore, these unsafe prompts are effective regardless of the image input associated with them – whether related or not. This work adds to the existing volume of work on safety evaluations on LLMs, and to this end presents interesting insights about the transferability of unsafe prompts between LLMs and multimodal LLMs. However, I have some concerns about the motivation and phrasing of the work, as well as the methodological choices of the work.
Reasons to accept
- Evaluating the tendency of multimodal LLMs to respond to unsafe multimodal prompts is an important and timely problem
- The paper is easy to follow, and well-structured
- I particularly liked how the authors expanded the unsafe textual prompts to include related/noisy images to increase the coverage of their experiments
Reasons to reject
- Major concern: The phrasing of the work is confusing and somewhat inconsistent . The main contributions of the work is to assess the transferability of unsafe textual prompts for LLMs to multimodal LLMs. To this end, the authors construct a synthetic benchmark that adds images to known unsafe prompts. I think the claims (and the title of the paper) should reflect that the benchmark is for evaluating the transferability of unsafe textual prompts, and is not a general-purpose benchmark. This is important because, in principle, multimodal LLMs, have a greater attack/jailbreak “surface”, as the input can span multiple modalities. However, from that broad attack/jailbreak surface, this “benchmark” only evaluates for a very specific, and perhaps, narrow subset of jailbreaks.
- Methodological weakness: Now, moving to the methodology that is adapted to construct the synthetic benchmark. First of all, the textual expansion of unsafe prompts is not IID, as the prompts to generate the unsafe prompts asks the LLM to generate 100 examples at once. Even though the authors have subsequent steps to filter out highly similar unsafe prompts from the generated set, it is unclear why the authors did not generate one unsafe prompt at once, which would have been a close approximation to the IID condition. Furthermore, there is not evaluation of the quality of these expanded unsafe prompts.
- Lastly, as a minor point, while discussing the results pertaining the role of image input, I would suggest the authors to clarify that in situations where the image encoder is not frozen, it is possible to leverage the image input much more prominently to design a jailbreak.
Very minor comment:
- The citations are rendered without parentheses in several places throughout the text
Questions to authors
**Q1:** Could the authors clarify why the prompt to expand the unsafe prompts instructed the LLM to generate 100 examples at once, instead of generating them one-by-one?
**Q2:** Are there any evaluations that establish the quality of these expanded prompts – perhaps on a subset of the data?