A person who claims to be a former member of the Anonymous hacker group has claimed responsibility for knocking The Pirate Bay offline for over a day.

Greg Sandoval/CNET

The claim is unconfirmed but a person calling himself "Nyre" left a message on Pastebin yesterday, saying he was the person who launched a distributed denial of service (DDoS) attack on The Pirate Bay, one of the world's best-known file-sharing services. The site was back up this morning.

As for the reason Nyre claims to have launched the attack: "The Pirate Bay was a press-release Website for Anonymous." ZDNet was first to report this story.

There are reasons, however, to view Nyre's claims with skepticism. Anonymous has communicated to the public through The Pirate Bay in the past, but it has also used other means such as YouTube and Twitter. In addition, some of Nyre's posts on Twitter include complaints about the lack of availability of his favorite kind of porn on The Pirate Bay. And some of his messages include what appear to be anti-Semitic and homophobic statements.

People claiming to be Anonymous members are now taking to Twitter to refute Nyre's claims, alleging he is a known attention seeker.

It should be noted, however, that is very possible for one person to launch a DDoS attack strong enough to take down a Web site, according to Arbor Networks, an Internet security firm that focuses on combating DDoS attacks.

The tools needed are easily accessible, according to Darren Anstee, solutions architect at Arbor Networks.

"While we are not in a position to speculate on any particular attack, Arbor's Worldwide Infrastructure Report, showed that ideologically motivated 'hacktivism' and vandalism were cited by a staggering 66 per cent of respondents as a motivating factor behind DDoS attacks on their businesses.

"But it's not just high-profile, politically connected organizations at risk," Anstee continued. "Any enterprise operating online, which applies to just about any type and size of business."

The most common theory circulating the Web about who is behind The Pirate Bay attack is that the file-sharing service recently angered members of Anonymous by rejecting the group's assistance.

Virgin Media, an ISP in the U.K., recently began blocking subscribers' ability to access The Pirate Bay. As a result, Anonymous launched a DDoS attack against Virgin Media.

The Pirate Bay implored Anonymous to switch tactics. "Don't fight them using their ugly methods," operators of The Pirate Bay wrote. "DDOS and blocks are both forms of censorship."