Microsoft said in a post on its website on Saturday that it was “aware of active attacks targeting on-premises SharePoint Server customers by exploiting vulnerabilities.” SharePoint is a Microsoft platform that allows customers to manage and share documents within their organizations.

An investigation is underway after hackers used a security flaw in Microsoft software to internationally infiltrate agencies and businesses over the weekend.

Microsoft warned users that hackers used a security flaw in its server software to attack government agencies and businesses around the world. The federal government, along with those in Canada and Australia, has launched an investigation into the hack that targeted SharePoint servers, The Washington Post reported.