Microsoft Says a Single Attacker Automated the ConnectWise Compromise With AI Agents

Microsoft Threat Intelligence attributes the ConnectWise supply chain compromise to a single actor, and says that actor automated the attack with an open-source tool that runs AI agents in place of a human operator. In an incident report published Oct. 21, 2026, Microsoft says the actor used it to attempt sign-ins to more than 2,250 customer tenants, the separate accounts that organizations hold in Microsoft 365, at 2,900 attempts a minute.

The report tells organizations to keep affected ConnectWise application connections switched off until ConnectWise issues formal restoration instructions, and to check which applications have signed in to their accounts and whether any application credentials or privileges were changed. Microsoft says the activity did not come from a compromise of, or a vulnerability in, its own systems, products or services.

The tool, ARTEX, is an open-source framework for penetration testing, meaning attacking a system to find its weaknesses. Microsoft describes it as a set of AI agents that can run from reconnaissance through to data theft with little human involvement, and that can be driven by any AI model.

Microsoft says the actor used ARTEX against hundreds of organizations from as early as September 2026, and that in several cases fewer than three hours passed between first targeting an organization and gaining privileged access to its cloud systems. The report says most of that targeting did not succeed, and that an earlier run of automated password guessing from the same infrastructure produced no successful sign-in.

Microsoft says ConnectWise published an initial advisory on Oct. 16, 2026, covering attempted unauthorized access associated with its Cloud Backup product. ConnectWise's backup application identities had been used to sign in to customer Microsoft 365 tenants, which Microsoft says let the actor authenticate without an interactive user sign-in.

Microsoft's report presents the attribution as its own assessment and tracks the actor as Storm-0940, which it describes as China-state aligned and focused on data theft. The report also says threat actors in several regions have used ARTEX, and that public reporting has noted the framework in data breaches at Korean financial institutions.