China-Linked Threat Actors Deploy ARTEX AI Framework in Mass Attack on 2,250 Microsoft 365 Tenants

Chinese state-aligned hackers leveraged ARTEX, an open-source AI-powered penetration-testing framework, to launch a coordinated campaign targeting over 2,250 Microsoft 365 tenants across government, defense, finance, and technology sectors. The attackers, attributed to Storm-0940, exploited compromised credentials from a ConnectWise Cloud Backup supply-chain breach to achieve successful authentication on at least 173 customer environments, according to Microsoft Threat Intelligence disclosures published October 21, 2026.