AI-Driven Hackers Breach 2,250 Tenants in Rapid ConnectWise Supply Chain Assault

Storm-0940, a threat actor aligned with the Chinese state, executed a large-scale supply chain attack against ConnectWise by deploying ARTEX, an open-source framework for agentic AI penetration testing. According to Microsoft, the group utilized stolen credentials from multi-tenant applications to attempt sign-ins across more than 2,250 Microsoft 365 tenants. This operation distinguished itself from traditional methods by using automated agents to accelerate reconnaissance and credential abuse, resulting in privileged access for some targets in under three hours.

The attackers employed automated password spraying, targeting 327 accounts across eight organizations. This generated over 151,000 failed login attempts without any successful breaches via this specific method. The ARTEX system, which utilizes large language model-driven agents to run autonomous tests, allowed for continuous scanning and OAuth application abuse with minimal human intervention. Microsoft noted that this pace leaves defenders with limited time to detect and respond to the incursion.

Storm-0940, active since 2021, targeted 14 industries including aerospace, defense, semiconductors, government, and think tanks. The activity did not stem from a vulnerability in Microsoft’s own systems but rather from unauthorized access to ConnectWise. At its peak on October 11, the password spray campaign recorded 2,900 failed attempts per minute, with 48 accounts experiencing over 1,000 failures each. Nearly 98% of this activity resulted in lockouts, yet the agents successfully signed in to customer tenants using compromised application credentials.

In one specific incident on October 15, security firm Huntress observed an application assigning itself to a top administrator role. This action triggered alerts in Microsoft Defender and involved planting new secrets set to expire in 2028. By October 16, Huntress confirmed unauthorized sign-ins for 162 tenants. The following day, nearly 1,000 Entra tenants showed sign-in activity from the attacking IP range, with more than 300 successful logins. The sequential nature of the sweep suggested the use of a script operating from a pre-defined target list.

The use of ARTEX marks a shift from traditional attack patterns, as the framework can integrate various AI models. Public reports this month linked similar technology to breaches at South Korean financial institutions, with CrowdStrike suggesting the suspect was China-based and used Anthropic’s Claude Code. The developer of ARTEX, known as Autumn-27, announced on GitHub that the project would become closed source and cease updates, according to Reuters.

ConnectWise suspended Cloud Backup, SaaS Security, and Cloud Management as a precautionary measure. The company has begun a phased restoration process, with recovery expected to take several days. There are currently no indicators that partner backup data was compromised. Microsoft advises customers to keep affected app connections disabled until formal restoration instructions are issued and to review activity logs from this month where possible.

It remains uncertain how the initial ConnectWise credentials were stolen or the exact number of tenants that were fully compromised. However, the rapid deployment of AI agents highlights a growing trend in supply chain attacks, where automated tools reduce the time between initial access and full control of an organization's identity systems.