While the type of attack is common, ProtonMail said the DDoS directed at it was “unprecedented in size and scope” in a blogpost on the assault. This is likely the biggest and most sophisticated DDoS attack to ever occur in Switzerland,” Yen said.

“But we know after speaking with the experts that came to our aid that there are few groups capable of carrying out an attack of this size and sophistication. Yen also said that he knew of “several dissident groups who are actively using ProtonMail”, and are based in countries known for hacking attacks. “We are still poring over the evidence and will be working with the Swiss federal cybercrime unit,” ProtonMail co-founder Andy Yen told the Guardian, adding that the source of the second attack had not yet been conclusively determined. It has become widely known in the US since its appearance on popular USA network drama Mr Robot.

ProtonMail is founded by scientists from European Organization for Nuclear Research, or Cern. The ransom was only for 15 bitcoin, or about $6,066, but the attacks did not stop when it was paid.

Protonmail encryption