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.

The Department of Energy, which oversees the agency that manages the US nuclear weapons stockpile, confirms it was affected by the SharePoint bug, but says it was 'minimally impacted.'

Microsoft blamed two Chinese nation-state actors for exploiting recently discovered security flaws in SharePoint to infiltrate vulnerable organizations, like schools, state governments, and the U.S. government’s top nuclear security agency.