A 16-year-old London youth has been detained in what is being dubbed the “world’s biggest cyber attack.” According to the Evening Standard, the boy was arrested at his home in London in April, but the news became known on Thursday.

“The suspect was found with his computer systems open and logged on to various virtual systems and forums,” a document on the case seen by the Evening Standard said. “The subject has a significant amount of money flowing through his bank account. Financial investigators are in the process of restraining monies.”

The boy, who has not been identified, is out on bail until later this year, the Standard reported. The London teenager was arrested by the National Cyber Crime Unit in an investigation codenamed Operation Rashlike.

As Mashable notes, the target of the Distributed Denial of Service attack was the Dutch anti-spam company Spamhaus, which targets email spammers by adding them to a blacklist and selling that information to Internet service providers.

The cyber attack, which happened in March, caused “worldwide disruption of the functionality” of the Internet, according to the briefing note cited by the Standard.

The only other person arrested, and the accused mastermind of the attack, Sven Olaf Kamphuis, a 35-year-old Dutchman living in Spain, was arrested at the same time as the London teenager.

The New York Times reports that Kamphuis worked for Cyberbunker, a hosting company that says it will host any website “except child porn and anything related to terrorism.” Cyberbunker was blacklisted by Spamhaus, which brought on the attack.

A DDoS attack takes place when hackers use an army of infected computers to send traffic to a server, causing a shutdown in the process. According to Mashable, the typical DDoS attack happens at a rate of 50 to 100 gigabits per second. The DDoS attack on Spamhaus had a peak rate of 300 gigabits per second, which is the largest on record.