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.

Hackers exploited a security flaw in common Microsoft Corp. software to breach governments, businesses and other organizations across the globe and steal sensitive information, according to officials and cybersecurity researchers.

A sweeping cyber espionage operation targeting Microsoft server software compromised about 100 different organizations as of the weekend, two of the organizations that helped uncover the campaign said on Monday.