Storm-0940 leverages AI agents in broad ConnectWise breach

The recent escalation in cyber threats has introduced a new variable into the supply chain attack landscape, one that relies heavily on automated intelligence. Microsoft has detailed how a China-state-aligned group deployed artificial intelligence tools to compromise a major IT management platform.

Microsoft's security team identified the actor as Storm-0940, a group active since 2021 with no known industry aliases. The organization utilized ARTEX, an open-source framework designed for agentic AI penetration testing. This system employs large language model driven agents to conduct autonomous security assessments, a capability that significantly accelerated the scanning and reconnaissance phases of the campaign.

The attack vector involved unauthorized access to the ConnectWise multi-tenant application. The group used stolen credentials from this application to authenticate without interactive user sign-ins. This allowed the AI agents to attempt sign-ins across more than 2,250 Microsoft 365 tenants. The automation enabled the agents to work continuously with minimal human input, a pace that left defenders with very little time to detect and respond to the intrusion.

The speed of the compromise was notable. In several instances, the attackers reached privileged access less than three hours after initially targeting a tenant. The operations included directory changes, reconnaissance, and modifications to identities and groups. In one specific tenant, the security firm Huntress observed an application adding itself to the top administrator role, a behavior that triggered specific alerts in Microsoft Defender.

Alongside the automated sign-ins, the group conducted a massive password spraying campaign. This targeted 327 accounts across eight organizations, resulting in more than 151,000 failed logons. At its peak on October 11, the system made 2,900 attempts per minute. Almost 98% of these attempts were locked out, indicating the brute-force approach alone was less successful than the application credential abuse. The targeted sectors included aerospace and defense, semiconductor, government, and think tanks.

The use of ARTEX marks a shift from traditional manual attacks to script-based, AI-driven operations. Public reporting this month linked the framework to breaches at South Korean financial institutions, where the suspected actor likely used the tool with Anthropic's Claude Code. The developer of ARTEX, known as Autumn-27, announced on GitHub that the project would stop being updated and become closed source, a move that may affect future threat modeling.

ConnectWise has suspended several services, including Cloud Backup and SaaS Security, as a precaution. The company has begun a phased restoration process, with recovery expected to take several days. There are no current indicators that partner backup data was compromised, though the company advises customers to review recent activity logs. Microsoft notes that a successful sign-in does not guarantee data exfiltration, but recommends keeping affected app connections disabled until formal instructions are issued.