A ransomware attack has taken down the computer systems to one of the world's biggest producers of aluminum.

On Tuesday, the Norwegian company Norsk Hydro reported that it's global IT systems had been hit with a strain of ransomware. "The situation for Hydro through this is quite severe," said company chief financial officer Eivind Kallevik in a press conference.

"The entire worldwide network is down, affecting our production as well as our office operations," he added.

The company's IT staff first detected the disruption around midnight local time. Apparently, the attack began within Norsk Hydro's US division, forcing some of its factories in the country offline.

Ransomware generally works by spreading over a computer network, and encrypting all the data on the affected machines. To free the systems, the victim must pay a heavy fee to the hacker, usually in cryptocurrency.

To contain the attack, Norsk Hydro has been isolating the computer networks of its aluminum factories, and switching to manual operations, Kallevik said. Office employees have also had to ditch their workstations for tablets and smartphones in order to communicate.

In total, Norsk Hydro has 35,000 employees based in over 40 countries. But despite the attack, the company's aluminum production remains normal. "We have no indications that the primary plants outside of Norway have been hit," Kallevik said, later adding. "As of today, those [financial] losses have been minimal."

Although Norsk Hydro didn't name the ransomware strain, local media has been reporting that the LockerGoga strain was responsible for the attack and may have spread over Microsoft's Active Directory software, which is available on the Windows Servers OS.

LockerGoga is a relatively new ransomware strain, but it may have been used to attack another company called Altran Technologies back in January. How the ransomware first infected Norsk Hydro isn't totally clear. But hackers can often launch the attacks via phishing emails or by exploiting a vulnerability in a company web server.

Security researchers have spotted a LockerGoga ransomware sample that was possibly used in the attack on Norsk Hydro. The sample includes a ransom note from the hacker, which says: "There was a significant flaw in the security system of your company. You should be thankful that the flaw was exploited by serious people and not some rookies."

During Tuesday's press conference, Norsk Hydro was asked whether the company would pay the ransom. In response, the company's CFO said it intends to address the situation by using backups the company made of its IT systems. Nevertheless, he warned the longer the company's IT systems remain down, the bigger financially hit it'll take from the disruption.