Storm-0940 Breaches 2,250 Microsoft 365 Tenants in 3 Hours Using ARTEX Framework

Starting in September 2026, China-state-backed threat group Storm-0940 used the public AI agent penetration-testing framework ARTEX to launch automated attacks against more than 2,250 Microsoft 365 tenants in a ConnectWise supply chain attack; for some tenants, the time from initial targeting to gaining privileged access was less than three hours.

Facts

Microsoft's security research team noted in an October report that Storm-0940 has been active since 2021 and that this campaign targeted aviation, defense, finance, government, and other critical sectors. In the four days before the attack, the group recorded more than 151,000 failed login attempts against 327 Microsoft 365 and Exchange Online accounts, peaking at 2,900 attempts per minute. The next day, the attack shifted to the ConnectWise Cloud Backup service, using the same malicious infrastructure and AI agents to penetrate downstream customer environments.

Microsoft characterized the incident as a milestone case of AI weaponization. The ARTEX framework was publicly released in July 2026, and public access was closed in October; it supports integration with any AI model, enabling an autonomous penetration process from reconnaissance to data exfiltration.

Mechanism

Storm-0940 used ARTEX's LLM-driven agents to accelerate scanning, conduct password spraying, and abuse OAuth applications. In some environments, the AI agents not only completed authentication but also performed Microsoft Graph and directory operations, including reconnaissance, modifying application credentials to establish persistence, and adjusting identities, groups, and privileged roles.

The ConnectWise service was temporarily shut down in October, and recovery is expected to take several days. Microsoft observed that the AI agents significantly accelerated the attack tempo, compressing the time to obtain privileged access in a single tenant to under three hours.

Industry Impact

The incident shows that a legally released open-source penetration tool was adopted at scale by nation-state actors within 90 days. Threat groups in multiple regions have been recorded using ARTEX to increase attack speed and scope. Once high-privilege third-party applications in the supply chain are abused, they can lead to lateral access beyond their intended purpose.

After the incident, ConnectWise customers were advised to keep connections disabled until the service was fully restored.

Strategic Assessment (Analysis, Not Fact)

Based on available public information, the dual-use AI tool took only about 90 days from release to weaponization, and this causal chain suggests that the control window for open-source security tools is narrowing. In historical precedents, similar penetration frameworks have been reused by multiple parties, but the ARTEX case's level of automation and attack density reached a new level. Stakeholders need to assess downstream abuse risks at the tool release stage; otherwise, supply chain security boundaries will blur further.