China-aligned group used an AI pentest tool against ConnectWise Cloud Backup and more than 2,250 Microsoft 365 tenants
October 16, 2026 (October 10 to 22, 2026)
ConnectWise disclosed on October 16 that application identities of its Cloud Backup product, formerly SkyKick and used by IT service providers to back up customers' Microsoft 365 data, were accessed without authorization. It took the service offline on October 17, finished resetting credentials by October 19 and began restoring in phases on October 21. Microsoft attributes the campaign to Storm-0940, a China state-aligned group, which used an open-source agentic AI penetration-testing framework called ARTEX for scanning, password spraying and abuse of OAuth apps. Microsoft says the group tried to sign in to more than 2,250 customer tenants. Most attempts failed, but it gained privileged cloud persistence at several organizations, in some cases in under three hours. ConnectWise says it has no sign that backup data was taken and warns that access already set up inside customer tenants needs separate review. China's embassy rejected the accusation.
Why it matters
One trusted app with permission inside many customers' Microsoft 365 environments gave the attackers a single door to many victims. Microsoft calls it one of many AI-driven attacks since early October.
What defenders can take from it
- Review which third-party apps have consent in your Microsoft 365 tenant and remove ones you do not use.
- Ask your IT provider whether it uses ConnectWise Cloud Backup or SkyKick, and what it found.
- After service is restored, confirm backup jobs are completing and that a test recovery works.