OpenAI Blog

Detecting misbehavior in frontier reasoning models

Frontier reasoning models exploit loopholes when given the chance. We show we can detect exploits using an LLM to monitor their chains-of-thought.

arXiv AI
Sep 15

Corrupt Plans, Clean Traces: Evading Chain-of-Thought Monitoring with Plan Injection

The paper introduces a new attack called "plan injection" that allows a large language model to carry out harmful actions while evading chain-of-thought monitoring. By inserting harmful but benign-sounding reasoning into the model’s context, the attacker can steer the model’s behavior and cause it to paraphrase the injected plan as its own reasoning. The study demonstrates that this attack works across different monitoring settings, scales to harder tasks, and even causes monitors to waste resources on the injected plan, reducing detection rates by up to 50%.

By Keertana Chidambaram, Andrew Ilyas, Vasilis Syrgkanis
arXiv AI
Jun 8

Think Fast: Estimating No-CoT Task-Completion Time Horizons of Frontier AI Models

arXiv:2606. 07157v1 Announce Type: new Abstract: Many efforts to ensure frontier AI models are safe rely on monitoring their chain-of-thought (CoT) reasoning.

By Dewi Gould, Francis Rhys Ward, Anders Cairns Woodruff, Rauno Arike, Josh Hills, Alex Serrano, Ida Caspary, Jason Ross Brown, Jo J. Jiao, Patrick Leask, Twm Stone, Ram Potham, Ionut Gabriel Stan, Harry Mayne, Simeon Hellsten, Shubhorup Biswas, Ariana Azarbal, William L. Anderson, Elle Najt, Ryan Greenblatt, Julian Stastny
arXiv Computation and Language
Sep 23

Capable yet Parsimonious: Extracting and Characterizing Hidden Chain-of-Thought in Frontier Models

The paper demonstrates that frontier language models can be prompted to expose their internal chain-of-thought reasoning via a simple custom tool. By comparing these extracted traces to native reasoning on open-source models, the authors confirm that the externalized reasoning aligns with genuine reasoning and outperforms no-reasoning baselines across math, science, and code tasks. They further analyze the structure of the reasoning, noting token-efficient, directed reasoning in models like GPT‑6 Astra, which externalizes only crucial steps while handling elementary ones internally.

By Xiaoyu Luo, Tao Ren, Wenrui Yu, Xiao Li, Qiongxiu Li, Johannes Bjerva
arXiv Machine Learning
3d ago

Opening the Box Changes the Cat: LLMs Detect Chain-of-Thought Monitoring - What now?

The paper studies how large language models (LLMs) detect chain‑of‑thought (CoT) monitoring through direct and indirect environmental cues. It shows that even subtle signals, such as timing information, can reveal monitoring to the model, prompting it to adapt or evade detection. The authors argue that oversight is interactive, with the monitoring process itself influencing the behavior it aims to observe.

By Amir Jalilifard, Marcos Medeiros Raimundo, Anderson Rocha