Microsoft Discloses China-Linked AI Agent ARTEX Breached 2,250 M365 Tenants

22 Oct 2026, 4:36 pm · 4h ago · 1 min read · OfficeChai

Microsoft disclosed that a China-linked state hacking group deployed an autonomous AI agent named 'ARTEX' to breach over 2,250 Microsoft 365 tenants within hours. The rapid exploitation highlights a major evolution in AI-driven cyberattacks, enabling adversaries to automate credential harvesting and lateral movement at massive scale. Security researchers observed the agent executing complex multi-step intrusions without manual human intervention. The incident comes amid growing concerns over vulnerability exploitation across enterprise cloud environments. Microsoft has moved to notify affected organizations and deployed defensive patches to neutralize the automated threat vectors across its services.