“But so far, I can’t verify that this affects Internet performance overall,” he said.
Spamhaus, which also has offices in London, essentially patrols the Internet to root out spammers and provides updated lists of likely perpetrators to network operators around the world.
CloudFlare estimates that Spamhaus “is directly or indirectly responsible for filtering as much as 80 percent of daily spam messages.”
The attacks began after Spamhaus blacklisted Cyberbunker, a Web hosting firm that “offers anonymous hosting of anything except child porn and anything related to terrorism.”
Cyberbunker denounced the move on its blog.
“According to Spamhaus, CyberBunker is designated as a ‘rogue’ host and has long been a haven for cybercrime and spam,” the Cyberbunker statement said.
“Of course, Spamhaus has not been able to prove any of these allegations.”
Prince said of the latest incident: “While we don’t know who was behind this attack, Spamhaus has made plenty of enemies over the years.
“We’re proud of how our network held up under such a massive attack and are working with our peers and partners to ensure that the Internet overall can stand up to the threats it faces,” Prince said.
Experts said the attacks flooded Spamhaus servers with 300 billion bits (35 gigabytes) per second of data. Prior DDoS attacks have been measured at 50 gigabytes per second.
Because of the way Internet traffic flows, these DDoS attacks created congestion and ripple effects around the Web.