Global businesses, including shipping giant A.P. Moeller-Maersk A/S, advertising firm WPP Group PLC and Russian oil company PAO Rosneft, reported significant cyberattacks Tuesday against their computer systems.
It was unclear how, or if, the attacks were related, but they spread simultaneously across Europe -- with some early reports of affected companies in the U.S. -- on the heels of a global attack in May. That virus, dubbed WannaCry, inflicted most of its damage on European businesses and institutions.
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The WannaCry malware locked computer systems that were old or weren't adequately patched, demanding ransom. The attack hit hospitals in the U.K., car factories in France and smaller businesses across the continent.
An adviser to Ukraine's interior minister said a version of the WannaCry virus had hit government computer systems in that country on Tuesday, Reuters reported, though the government said shortly after the nation's most critical systems were safe.
The extent of the operational disruption was unclear at the affected companies.
Russia's state-controlled oil company, PAO Rosneft, said it was under a "massive hacker attack" that could have serious consequences but said its oil production hadn't been affected.
Rosneft, the world's largest publicly listed oil company by production, said it had contacted law-enforcement authorities about the attack. The company's website was down on Tuesday, but its official Twitter accounts spread news of the attack.
The company said it had recently switched to a different oil reserve-control system, so "neither oil production nor preparation processes were stopped."
Rosneft produces over 4 million barrels of oil every day on average, making it the biggest producer in a country that pumps more crude oil than any other.
Denmark's shipping giant Maersk said Tuesday that its computer systems had been brought down by a cyberattack. The breakdown is affecting multiple computer systems across several business units, a Maersk spokeswoman said, adding the company was assessing the situation. The company runs Maersk Line the world's largest container operator by capacity.
The spokeswoman said she couldn't provide details on how the computer outage was affecting the company's flagship business, Maersk Line, the world's largest container operator by capacity.
WPP, the London based advertising conglomerate, said its I.T. systems across several companies were affected by a "suspected cyber attack" on Tuesday.
"We are taking appropriate measures [and] will update asap," the advertising company said in a tweet.
Write to David Gauthier-Villars at David.Gauthier-Villars@wsj.com and Michael Amon at firstname.lastname@example.org
(END) Dow Jones Newswires
June 27, 2017 11:18 ET (15:18 GMT)