The attorney for Marcus Hutchins, who has broad support in the information-security community, said the 23-year-old hacker would contest the charges. She said he would not be released until Monday because there wasn't enough time to post bail after Friday's afternoon ruling.
Hutchins is due in federal court in Milwaukee on Tuesday.
The UK resident gained overnight fame with quick thinking in May when he helped curb the spread of the WannaCry ransomware attack that had crippled thousands of computers worldwide.
The conditions of his release came as a relief for his supporters.
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"This is excellent news," said Nicholas Weaver, a computer scientist at the University of California at Berkeley. "The indictment is remarkably shallow even by indictment standards, which is disappointing because it adds considerable uncertainty and fosters distrust with the general security community."
Las Vegas-based attorney Adrian Lobo said money for Hutchins' bond would come from a variety of supporters and family in the US and abroad. The Electronic Frontier Foundation, a digital leading civil liberties non-profit, said it helped arrange Hutchins counsel and was working to find him an attorney to provide "the best possible defense."
Weaver said federal prosecutors and the FBI were making a mistake by not providing more details about the crimes it alleges Hutchins committed. "Having more information would act to reassure the larger security community," he said.
At the hearing, assistant US attorney Dan Cowhig said Hutchins admitted to authorities in an interview following his arrest that he was the author of the malware code and sold it.