Hackers exploited a possible security flaw in widely used Microsoft server software over the past few days, it has emerged.

The hack which compromised SharePoint servers is currently under investigation by the American government and Canadian and Australian partners, the Washington Post reported.

Officials said that this attack compromises servers within an organization and not those in the cloud.

Tens of thousands of server software programs used to share and manage documents are currently vulnerable.

“We are seeing attempts to exploit thousands of SharePoint servers globally before a patch is available,” said Pete Renals, a senior manager with Palo Alto Networks’ Unit 42, in a statement to customers. “We have identified dozens of compromised organizations spanning both commercial and government sectors.’’

This flaw was previously unknown which has prompted the hacking to be called a “zero-day” attack and occurred after Microsoft fixed a security flaw this month.

Microsoft has advised users to make modifications to the existing server programs or unplug them from the internet.

“Anybody who’s got a hosted SharePoint server has got a problem,” Adam Meyers, senior vice president with CrowdStrike, a cybersecurity firm, told The Washington Post. “It’s a significant vulnerability.’’

It is not clear who is responsible for these hacks.