BREWER, Maine — The Brewer School Department found a way to avoid shelling out $1,400 to unlock its computers from a “ransomware virus” that corrupted the district’s computer system last week, Superintendent Cheri Towle said Wednesday.

The malware locked up the school department’s computer system at around 1:30 p.m. May 10 and came with a demand for $1,400 to decrypt the district’s files, the superintendent said. Towle on Friday indicated the school department paid the ransom in Bitcoin, an anonymous online currency.

But on Wednesday she amended her statement to say that the school had only bought a portion of the Bitcoin required to pay the ransom before information technology employees found a backup of the files.

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“We started to get bitcoins but didn’t need to finish the process due to finding the backup,” Towle said. “We are able to sell the $450 worth of bitcoin we purchased to get our money back.”

Ransomware exploits a flaw in Microsoft software and encrypts systems and threatens to destroy data if a ransom is not paid. The Brewer attack came the same week as a massive cyberattack that Interpol estimated hit more than 200,000 people in about 150 countries, the Washington Post reported.

Staff in Brewer used cellphones to keep tabs of emails and to communicate, and wireless service was restored to some teachers on Wednesday, Towle said.

“[The school district’s wireless] should be fully operational on Monday,” the superintendent said. “Our IT department has worked hard to solve this problem and put in additional securities to help prevent [problems] in the future.”