Red-Teaming Anthropic's Internal Agent Monitoring Systems

In collaboration with Anthropic, a METR staff member (David Rein) recently spent three weeks red-teaming a subset of Anthropic’s internal agent monitoring and security systems, many of which are described in the Opus 4.6 Sabotage Risk Report (Appendix 8.4, especially 8.4.8). Anthropic provided substantial access to relevant internal systems and information, and made staff available to answer questions and provide feedback throughout the exercise. The exercise discovered several specific novel vulnerabilitie