A massive cyberattack launched by the Dutch web hosting company CyberBunker has caused global disruption of the web, slowing down internet speeds for millions of users across the world, according to a BBC report.

CyberBunker launched an all-out assault, described by the BBC as the world’s biggest ever cyberattack, on the self-appointed spam-fighting company Spamhaus, which maintains a blacklist used by email providers to filter out spam.

The Dutch company famously has its headquarters housed in a five-story former NATO bunker, and is known for offering its services to any website except “those that promote child porn and anything related to terrorism”. Due to this lax policy, its servers have often been linked to spamming activity and has been routinely condemned by anti-spam campaigners.

But recently, Spamhaus went one step further than just criticizing the company, adding CyberBunker to its blacklist for allegedly disseminating millions of spam messages. CyberBunker responded with what security experts believe is the largest known DDoS attack in the history of the web, bombarding its Spamhaus’ servers with millions of requests a second to make them inaccessible to normal users. Experts said that at one point, they recorded more than 300 billion bits per second aimed at Spamhaus by a network of computers, a figure that dwarfs the size of typical DDoS attacks.

An attack of this scale would be headline news in itself, but just as spectacular has been the fallout from the assault, with thousands of internet users across the world reporting disruption to web services like Netflix and delayed access to numerous other websites.

The disruption is said to be due to the unique method of attack used by CyberBunker, which is targeting Spamhaus’ Domain Name System (DNS) servers that are connected to the web’s underlying infrastructure. Spamhaus itself says that it’s so far managed to fend off the attack and keep its servers online, thanks in part to the enormous size of its DNS servers and also through assistance from companies like Google, that have offered part of their own infrastructure to take some of the strain.

“We’ve been under this cyber-attack for well over a week,” Spamhaus CEO Steve Linford told the BBC.

“But we’re still up – they haven’t been able to knock us down. Our engineers are doing an immense job in keeping it up – this sort of attack would take down pretty much anything else. If you aimed this at Downing Street, they would be down instantly.”

Mr. Linford added that five different law enforcement agencies were now investigating the attack, but declined to mention which countries were involved out of fear that their own infrastructure could come under attack.

At first glance readers might conclude that CyberBunker is being incredibly irresponsible in its actions, but not everyone believes that Spamhaus is the innocent party in this affair. Internet activist Sven Olaf Kamphuis told the New York Times that as far as he was concerned, Spamhaus was “abusing its influence” as the number one black-lister of spammers and that CyberBunker was right to retaliate.

Meanwhile, all CyberBunker will say is that it has resisted a number of efforts by Dutch police to arrest its members, without commenting on whether or not it really is behind the attack.

Sounds like a fun battle! We’ll be sure to keep following this one and let you know the outcome.