Cybersecurity's next phase: Cyber-deterrence

Prosecutors have said they believe Boykov did not act alone and were now looking for instigators of the cyberattack and contractors they used.

Cyberattackers pose many threats to a wide range of targets. Russia, for example, was accused of hacking Democratic Party computers throughout the year, interfering with the US presidential election.

Then there was the unknown attacker who, on a single October day, used thousands of Internet-connected devices, such as digital video recorders and cameras compromised by Mirai malware, to take down several high-profile websites, including Twitter.