Europol has announced that it has carried out a major crackdown on cybercriminal actors in cooperation with the police authorities in 15 countries as part of an ongoing international crackdown known as PowerOFF.

Included in the effort are the Australian Federal Police, the UK’s National Crime Agency, and the US Department of Justice, Federal Bureau of Investigation, Homeland Security Investigations, and Defense Criminal Investigative Service.

In connection with the crackdown, 300 users have been identified, while three administrators have been arrested in France and Germany.

Furthermore, 27 booter and stresser sites have been shut down, including zdstresser.net, orbitalstress.net, and starkstresser.net.

According to Europol, these sites enabled cybercriminals and hacktivists to flood targets with illegal traffic as part of DDoS attacks aimed economic sabotage, financial gain, and ideological statements.

Europol also noted that the holiday season “has long been a peak period for hackers to carry out some of their most disruptive DDoS attacks, causing severe financial loss, reputational damage and operational chaos for their victims.”

DDoS attacks have also been increasingly targeting critical infrastructure of late.

In October, Cloudflare reported thwarting the largest DDoS attack seen to date. According to the content distribution network provider, DDoS attacks are increasing in amplification in part due to the growing number of vulnerable or poorly secured IoT devices.