Microsoft: China-aligned Storm-0940 ran the open-source ARTEX AI agent against 2,250-plus Microsoft 365 tenants after the ConnectWise Cloud Backup compromise, reaching privileged access in under three hours in several cases
Microsoft Security Research and Microsoft Threat Intelligence published on Oct 21 (page last modified Oct 23) their assessment that Storm-0940, a China-state-aligned actor active since 2021, was responsible for the supply-chain compromise of ConnectWise's multi-tenant Cloud Backup application, which Huntress surfaced publicly on Oct 15 and ConnectWise acknowledged in an advisory on Oct 16. Microsoft says the actor used ARTEX, an open-source Go-based multi-agent LLM penetration-testing framework that runs reconnaissance through data exfiltration with little human interaction, from as early as September 2026, and after the unauthorized access used it to attempt sign-ins to more than 2,250 tenants, targeting 'hundreds of organizations globally'. In several environments the agents went on to directory operations for persistence, including credential changes and attempts to alter privileged roles, and Microsoft reports 'multiple instances where the time from initial targeting to privileged access was less than 3 hours'. A separate ARTEX-driven password spray on Oct 10 to 14 hit 327 accounts at eight organizations with more than 151,000 failed logons, peaking at 2,900 a minute on Oct 11, and produced no successful authentication. Microsoft cautions that the majority of the targeting was not successful, that an affected application or a successful sign-in 'does not necessarily indicate that customer data was accessed or exfiltrated', and that no Microsoft vulnerability was involved. The Record (Oct 22) reports that the ARTEX developer, Chinese security engineer Li Puhua, said on GitHub on Oct 8 that the tool had been misused and 'will be converted to closed source', and that foreign ministry spokesperson Mao Ning denied any knowledge of the incidents, per Reuters. The same framework is the one CrowdStrike tied to the Korean bank breaches.
Damage
Privileged persistence in an unstated number of organizations' Microsoft 365 tenants across 14 sectors, per Microsoft; data theft not confirmed; ConnectWise Cloud Backup service disrupted
In their words
“multiple instances where the time from initial targeting to privileged access was less than 3 hours”
Sources
Microsoft Security, second source. Added late: disclosed Oct 21 and carried on the Wire since Oct 22, but not scored until Oct 25. Dated to 'as early as September 2026' (Microsoft), month precision. Microsoft gives no count of organizations where privileged access was gained ('many organizations'); the 2,250 figure is attempted sign-ins, not compromises. Attribution is Microsoft's assessment; the foreign ministry's denial is as reported by The Record, citing Reuters. Novelty 3: the first publicly attributed use of an agentic AI penetration-testing framework by a state-aligned actor in a supply-chain compromise; the ARTEX tool itself was already on the index (korea-banks-artex).
Factor ratings and the score are this index’s judgments by a published formula; facts, dates and figures come from the linked sources. Where a lawsuit is pending, the summary reports allegations, not findings.
