AI-Driven Hacks: Chinese Group Uses Agents to Storm Microsoft Tenants
A China-aligned threat actor leveraged autonomous AI tools to breach thousands of Microsoft 365 accounts through a supply chain weakness in ConnectWise.
By Kwame Silva ·
Supply chain attacks have long been a headache for IT security teams, but a recent incident has introduced a faster, more automated twist. Microsoft has revealed that a group known as Storm-0940 used artificial intelligence agents to execute a massive breach through the ConnectWise platform.
The attack relied on ARTEX, an open-source framework that drives large language models to perform penetration testing autonomously. By exploiting stolen credentials from ConnectWise applications, the attackers managed to sign in to more than 2,250 distinct Microsoft 365 tenants. These sign-ins occurred without any interactive user action, meaning the apps themselves were used as the entry point.
Speed was the defining characteristic of this operation. In several cases, the intruders achieved privileged access levels within less than three hours of initially targeting a tenant. The AI agents worked around the clock with minimal human input, a pace that Microsoft notes leaves defenders with very little time to detect the intrusion and mount a response.
The group also employed automated password guessing, known as password spraying, against 327 accounts across eight organizations. This generated over 151,000 failed logon attempts, though none were successful. The use of ARTEX accelerated scanning, reconnaissance, and the abuse of OAuth applications, allowing the attackers to move through their target list with mechanical precision.
Storm-0940, active since 2021, is described by Microsoft as a China-state aligned actor with no known industry aliases. The group targeted industries including aerospace, defense, semiconductors, government, and think tanks, with 14 specific sectors listed. Microsoft clarified that this activity did not stem from a vulnerability in its own systems, but rather from unauthorized access to the multi-tenant ConnectWise application.
At the peak of the attack on October 11, the password spraying reached 2,900 attempts per minute, resulting in more than 111,000 failures that day. Almost 98 percent of this activity resulted in account lockouts. However, the AI agents successfully used four application credentials to execute over 200 sign-ins in under four minutes from the same IP range, moving quickly through Graph and directory operations.
Security firm Huntress observed one tenant on October 15 where an app added itself to the top administrator role. This behavior triggered a specific Microsoft Defender alert. The attackers also planted new secrets set to expire in 2028. By October 16, unauthorized sign-ins were confirmed for 162 tenants, and a day later, nearly 1,000 tenants showed sign-in activity from the attacking IP, with more than 300 of those succeeding.
The use of ARTEX marks a shift from traditional attack methods. While other groups in different regions are adopting similar tools, public reports have linked the framework to recent breaches at South Korean financial institutions. The developer of ARTEX, who uses the handle Autumn-27, announced on GitHub that the project would no longer be updated and would become closed source, a move reported by Reuters.
ConnectWise has suspended several services as a precaution and begun a phased restoration process, with recovery expected to take several days. The company has not yet found indicators that partner backup data was compromised. Microsoft advises customers to keep affected app connections disabled until formal instructions are issued and to review activity logs from this month to assess the extent of the impact.
