Cyber attack sweeps globe, researchers see 'WannaCry' link

A message demanding money is seen on a monitor of a payment terminal at a branch of Ukraine's state-owned bank Oschadbank after Ukrainian institutions were hit by a wave of cyber attacks earlier in the day, in Kiev, Ukraine, June 27, 2017. REUTERS/Valentyn Ogirenko

MOSCOW/KIEV/WASHINGTON (Reuters) - A major global cyber attack disrupted computers at Russia's biggest oil company, Ukrainian banks and multinational firms with a virus similar to the ransomware that infected more than 300,000 computers last month.

The rapidly spreading cyber extortion campaign, which began on Tuesday, underscored growing concerns that businesses have failed to secure their networks from increasingly aggressive hackers, who have shown they are capable of shutting down critical infrastructure and crippling corporate and government networks.