The department has been holding daily calls with Microsoft since the zero-day was discovered, the DOD CIO said at an event Thursday.

A cyber-espionage campaign centred on vulnerable Microsoft software now involves the deployment of ransomware.

The hackers behind the initial wave of attacks exploiting a zero-day in Microsoft SharePoint servers have so far primarily targeted government organizations, according to researchers and news reports.

More information has emerged on the ToolShell SharePoint zero-day attacks, including impact, victims, and threat actors.

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 has released a critical patch for a security flaw in its SharePoint software. Hackers actively exploited this vulnerability, targeting businesses and US government agencies. The company issued the fix between July 19 and 20.

Microsoft is facing global fallout from a serious SharePoint server flaw that has impacted more than 400 organizations, according to Bloomberg. Dutch cybersecurity firm Eye Security reported a sixfold surge in SharePoint-related cyberattack victims within days.

Microsoft identified three China-based hacking groups targeting SharePoint vulnerabilities in the ongoing cyberattack, and urged customers to ensure they've applied security updates.