The strikes follow the global ransomware assault involving the WannaCry virus that affected hundreds of thousands of computers in more than 150 countries as extortionists demanded $300 in bitcoin from victims. And Russia's Rosneft is one of the largest oil conglomerates in the world.
Ukraine was particularly badly hit, with Prime Minister Volodymyr Groysman describing the attacks on his country as "unprecedented".
Its Microsoft Windows systems were temporarily disconnected, and radiation monitoring in the area of the industrial site is being carried out manually, it said.
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The officials told Reuters they believed the test could be part of Pyongyang's programme to develop an inter-continental ballistic missile.
He said that a radiation leak was avoided due to "excess levels of control" at the plant but staff have had to manually monitor radiation levels, because they can't access the metrics on their computers.
Victims were locked out of their computer and told to purchase a key to reinstate access.
"We are talking about a cyberattack", said Anders Rosendahl, a spokesman for the Copenhagen-based group.
The Ukrainian central bank said a number of banks and companies, including the state power distributor, were hit by a cyber attack that disrupted some operations.
"We confirm our company's computer network was compromised today as part of global hack", American pharmaceutical company Merck & Co tweeted. Dutch daily Algemeen Dagblaad says that container ship terminals in Rotterdam run by a unit of Maersk were also affected. Rosneft, a massive Russian energy company, said it had been impacted, as well.
Ukraine's National Bank said in a statement that an "unknown virus" has caused banks "difficulties in serving clients and carrying out banking operations".
National Weather Service issues flash flood watch
Cindy also caused widespread coastal highway and street flooding and several short-lived tornadoes, but no other deaths. Louis, Missouri, was vacationing with family on the Alabama coast when he was hit by a log carried in on a big wave.
Russian metals giant Evraz said its IT systems had been affected too, Russia's RIA news agency reported.
Rob Wainwright, executive director at Europol, said the agency is "urgently responding" to reports of the new cyber attack.
While here in the United Kingdom the advertising agency WPP said its systems were among those affected.
"The long-lasting impact of a cyberattack can not be overstated", he said.
The fight against cyberattacks has sparked exponential growth in global protection spending, with the cyber security market estimated at $120 billion this year, more than 30 times its size just over a decade ago.
Several security experts have speculated that the ransomware could be a variation of a malware called Petya, but cybersecurity firm Kaspersky Labs said that the attack could also be an entirely new program based on Petya or something similar.
UAE envoy attacks Qatar over extremism as Gulf feud escalates
He said Qatar, like Turkey, had been a staunch opponent of Islamic State terrorists, adding, "Let's stop fooling ourselves". Erdoğan rejected accusations that Qatar supported terrorism, arguing that the country had been a staunch opponent of ISIL.
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