European Union and U.S. authorities announced last week that they had disabled the Avalanche network, an international cybercrime operation – but not before it had entrapped hundreds of thousands of victims to pay bitcoin ransoms to free up infected computer networks.

Among those victims was a state prosecutor's office in Pennsylvania, which was identified as the office of Allegheny County district attorney, Stephen Zappala Jr. – which acknowledged that it paid $1,400 to free up its network.

The Avalanche group had operated since at least 2010 and infected at least 500,000 computers worldwide, said Soo Song, acting U.S. Attorney in Pittsburgh. "The takedown of Avalanche was unprecedented in its scope, scale, reach and level of cooperation among 40 countries," Song said.

The prosecutor's office was hit by ransomware in January 2015 when an employee clicked on a link embedded in phishing email, Zappala said. Phishing is a process computer hackers use to try to get people to unwittingly install malware on their computer by clicking on what appears to be a legitimate internet link. The employee "opened the link because it appeared to go back to a legitimate government agency," Zappala said. The link compromised the district attorney's computer system, which has since been upgraded to fend off similar attacks, he said.

According to federal court documents., 2 unidentified Pennsylvania companies also were targets of the cybercrime operation.