Businesses around the world scrambled on Saturday to prepare for a renewed cyber attack, convinced that a lull in a computer offensive that has stopped car factories, hospitals, schools and other organizations in around 100 countries was only temporary.

The pace of the attack by a destructive virus dubbed WannaCry slowed late on Friday, after the so-called “ransomware” locked up more than 100,000 computers, demanding owners pay to $300 to $600 get their data back.

“It’s paused but it’s going to happen again. We absolutely anticipate that this will come back,” said Patrick McBride, an executive with cyber-security firm Claroty.

Symantec predicted infections so far would cost tens of millions of dollars, mostly from cleaning corporate networks. Ransoms paid so far amount to only tens of thousands of dollars, one analyst said, but he predicted they would rise.

Companies rushed to protect Windows systems with patches that Microsoft released last month and on Friday. WannaCry exploited a vulnerability to spread itself across networks, a rare and powerful feature that caused infections to surge on Friday.

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