Toru Nakanishi

h-index12
2papers

2 Papers

CRAug 25, 2025
Tricking LLM-Based NPCs into Spilling Secrets

Kyohei Shiomi, Zhuotao Lian, Toru Nakanishi et al.

Large Language Models (LLMs) are increasingly used to generate dynamic dialogue for game NPCs. However, their integration raises new security concerns. In this study, we examine whether adversarial prompt injection can cause LLM-based NPCs to reveal hidden background secrets that are meant to remain undisclosed.

CRAug 25, 2025
Prompt-in-Content Attacks: Exploiting Uploaded Inputs to Hijack LLM Behavior

Zhuotao Lian, Weiyu Wang, Qingkui Zeng et al.

Large Language Models (LLMs) are widely deployed in applications that accept user-submitted content, such as uploaded documents or pasted text, for tasks like summarization and question answering. In this paper, we identify a new class of attacks, prompt in content injection, where adversarial instructions are embedded in seemingly benign inputs. When processed by the LLM, these hidden prompts can manipulate outputs without user awareness or system compromise, leading to biased summaries, fabricated claims, or misleading suggestions. We demonstrate the feasibility of such attacks across popular platforms, analyze their root causes including prompt concatenation and insufficient input isolation, and discuss mitigation strategies. Our findings reveal a subtle yet practical threat in real-world LLM workflows.