The IT system of the world’s largest ocean carrier are down, thanks to a massive cyber attack that is spreading across the globe.

Russia’s biggest oil company, Ukrainian banks, advertising firms, and pharmaceutical companies were among other concerns reportedly hit by a ransomware attack called GoldenEye, which experts say is a variant of an existing ransomware family called Petya. Ransomware is a type of malicious software that infects a computer and restricts users’ access to the infected machine until a ransom is paid to unlock it.

“Maersk IT systems are down,” said a notice on the ocean carrier’s website. “We can confirm that Maersk IT systems are down across multiple sites and business units due to a cyber attack. We continue to assess the situation.”

The US Department of Homeland Security confirmed it has received multiple reports of Petya ransomware infections occurring in networks in many countries around the world. “Individuals and organizations are discouraged from paying the ransom,” the notice said, “as this does not guarantee that access will be restored. Using unpatched and unsupported software may increase the risk of proliferation of cybersecurity threats, such as ransomware.”

Experts say the attack is reminiscent of Wannacry, which spread around the globe on Windows systems last month until a British researcher figured out how to bring it down. After Wannacry, Microsoft strongly urged users to install a security patch. It appears that those who heeded that advise were not affected by the latest attacks. The malware is spread by downloading Word documents or PDF files attached to emails.

Victims receive the following message:

“If you see this text, then your files are no longer accessible, because they have been encrypted. Perhaps you are busy looking for a way to recover your files, but don’t waste your time. Nobody can recover your files without our decryption service.”