AI agents helped Chinese crew hit 2,250 Microsoft 365 tenants

Microsoft said this week that attackers linked to China used AI agents and compromised ConnectWise application credentials to target more than 2,250 Microsoft 365 tenants, according to a report published on 22 October 2026. The company attributed the activity to Storm-0940, an espionage group it says has been operating since at least 2021. In some cases, Microsoft said, the attackers went from selecting a target to holding privileged cloud access in less than three hours.

The findings add detail to the ConnectWise security incident. The IT management vendor pulled its Cloud Backup, SaaS Security and Cloud Management services offline after discovering unauthorised access to application identities. ConnectWise did not initially say who was responsible. Microsoft has now named Storm-0940.

According to Microsoft, the group used ARTEX, an open source penetration-testing framework written in Go that uses AI agents to automate reconnaissance, vulnerability discovery, credential attacks and data theft. Microsoft says Storm-0940 began using the tool as early as September to target organisations worldwide, including government agencies, defence contractors, banks, manufacturers and technology firms.

Between 10 October and 14 October 2026, the attackers made more than 151,000 failed sign-in attempts against 327 accounts at eight organisations, Microsoft said. It observed no successful logins from that password-spraying run. The attackers then switched to the compromised ConnectWise application identities, which allowed them to exploit permissions customers had already granted to ConnectWise services without needing an interactive user login.

With ARTEX driving the activity, Storm-0940 attempted to authenticate against more than 2,250 Microsoft 365 tenants, at times reaching 2,900 attempts a minute, Microsoft said. The company also observed AI-accelerated activity through Microsoft Graph, including reconnaissance, changes to application credentials and attempts to modify privileges. Microsoft said those privilege changes could potentially let the attackers remain in place even after the original credentials were revoked.

Most attempts failed. Even so, Microsoft said the group established persistent privileged access at numerous organisations. It has not disclosed how many customers were compromised or whether any data was stolen, and cautioned that a successful login does not necessarily mean information was accessed.

ConnectWise chief executive Manny Rivelo said the company had contained the affected application connections and was gradually restoring services. Shutting down those connections would not necessarily remove attackers who had already established a foothold in customer environments, The Register noted.

This is not the vendor's first such disclosure. In May 2025, ConnectWise said a "sophisticated nation-state actor" had broken into its systems and compromised a small number of customers using its ScreenConnect remote access software. The Register reported there is nothing to suggest the two attacks are linked.

Storm-0940 is also not the only group using the framework. Microsoft says it has seen attackers from several geographic regions using ARTEX, which is freely available for penetration testing.

The underlying techniques are familiar: stolen credentials, password spraying and abuse of application permissions. Microsoft's point is about speed. AI helped Storm-0940 run those techniques faster, with some attacks moving from initial targeting to privileged cloud access in under three hours.