Claude Code AI Discovers Technique to Turn Dormant Model Neurons Into Hidden Malware Triggers

Microsoft researchers discovered that attackers can embed hidden backdoors inside AI model weights by manipulating dormant neurons — neurons that are normally inactive but can be activated by a specific attacker-controlled trigger. Once triggered, the compromised AI agent can download and execute malicious code without any external malware loader being present. Because the backdoor lives entirely within the model's internal parameters, standard safety evaluations and behavioral testing fail to detect it. This matters because organizations increasingly deploy third-party or open-source AI models in production pipelines, creating a new and largely unmonitored supply chain attack surface. Trust in a model's benchmark performance is no longer sufficient assurance of its integrity.