Hours after Microsoft revealed hacking groups affiliated with the Chinese government have been exploiting a flaw in its SharePoint software, Bloomberg News reports that the National Nuclear Security Administration has also been breached in the attacks.

Microsoft says the Chinese threat actors Linen Typhoon, Violet Typhoon, and Storm-2603 have been exploiting the ToolShell zero-days.

State CISOs in North Carolina and Arizona said their teams began work immediately to ensure on-prem SharePoint systems were secure, following the recent disclosure of an active zero-day exploit.

A security patch released by Microsoft earlier this month failed to fully fix a critical flaw in the U.S. tech company's SharePoint server software that had been identified at a hacking competition in May,

Dubbed a “zero-day” because it leverages a previously undisclosed digital weakness, the hacks allow spies to penetrate vulnerable servers and potentially drop a backdoor to secure continuous access to victim organisations.

A major cyberespionage operation targeting Microsoft's SharePoint server software has compromised about 100 organizations worldwide. The operation exploits a zero-day vulnerability, allowing hackers to install backdoors on affected servers.