Microsoft has formally tied the exploitation of security flaws in internet-facing SharePoint Server instances to two Chinese hacking groups called Linen Typhoon and Violet Typhoon as early as July 7, 2025, corroborating earlier reports. The tech giant said it also observed a third China-based threat actor, which it tracks as Storm-2603, weaponizing the flaws as well to obtain initial access to target organizations. "With the rapid adoption of these exploits, Microsoft assesses with high confidence that threat actors will continue to integrate them into their attacks against unpatched on-premises SharePoint systems," the tech giant said in a report published today. A brief description of the threat activity clusters is below - Linen Typhoon (aka APT27, Bronze Union, Emissary Panda, Iodine,…