Show HN: Tensor Trust – A multiplayer prompt injection CTF game (opens in new tab)

Prompt injection is a huge security problem for LLM-based apps. Language models don’t have a clean separation between data and instructions, so any LLM that processes untrusted data (e.g. by searching the web) is at risk of being hijacked by malicious instructions embedded in the data.

We’re a research team from UC Berkeley, Georgia Tech, and Harvard who built this game to help us understand how people construct prompt injection attacks, and how to defend against them. The game mechanics are explained on the landing page: attackers have to find an input that makes the LLM say "access granted". Defenders have to stop this from happening except when they input a secret password of their choice. These rules have led to some interesting strategies:

* Most simple defenses can be bypassed by writing "[correct access code]" in the attack box. It's surprisingly hard to defend against this!

* GPT 3.5 Turbo has a few known glitch tokens that it cannot output reliably. It turns out that one of these, "artisanlib", tends to subvert instructions in surprising ways: sometimes it makes the model say "access granted" immediately, or output the defender's instructions verbatim, or even output the instructions in reverse.

* Although these are instruction-following models, they still love to complete patterns, and few-shot prompts tend to make for powerful attacks and defenses.

The game is live at https://tensortrust.ai/, and we recently added support for PaLM and Claude Instant (choose your model from the "defend" page"). If you’re interested in reading more about the research, or you want to download our paper or code, then head to https://tensortrust.ai/paper/