A hacker affiliated with Anonymous has claimed responsibility for knocking domain provider GoDaddy offline today. The attack appears to have also affected all sites hosted by GoDaddy.Twitter user @AnonymousOwn3r, which is operated by the self-proclaimed "security leader of anonymous," has taken responsibility for the outage. GoDaddy has acknowledged the outage on Twitter and claims to be "working on it." Two Twitter users who responded to GoDaddy's status alert claim their GoDaddy-hosted websites are currently offline, suggesting the attack may impact a significant number of websites. Indeed, shortly after announcing the attack, @AnonymousOwn3r posted a tweet asking if its followers wanted to see the hacker "put 99% of the global internet" offline.MORE: The Anonymous hit listFROM ANONYMOUS TO HACKERAZZI: The year 2011 in security mischief makingThe hacker has repeatedly insisted that the attack was not launched or endorsed by the Anonymous collective, but was instead a rogue mission undertaken alone. The official Anonymous Twitter account, which had been dormant since April, openly mocked @AnonymousOwn3r and questioned whether the Twitter user behind it was taking credit for an outage that occurred organically. At one point, the Twitter account for Anonymous declares outright, "it wasn't us."In one tweet, the hacker claims the attack was launched to "test how [its] cybersecurity is safe," and "for more reasons that I cannot talk [about] now."One tweet sent to and retweeted by @AnonymousOwn3r mentions recent GoDaddy advertisements that boast load balancers for its hosting servers, suggesting the hacker may be attempting to put the company's advertising to the test.GoDaddy's support for the Stop Online Piracy Act (SOPA) in late 2011 likely didn't help its favor in the eyes of Anonymous hackers. In a written testimony to the House Judiciary Committee in November 2011, GoDaddy brushed aside any censorship concerns in favor of policing online piracy."Not only is there no First Amendment concern, but the notion that we should turn a blind eye to criminal conduct because other countries may take oppressive steps in response is an affront to the very fabric of this nation," the document reads. A link would be provided, but the site it links to is currently offline.The @AnonymousOwn3r Twitter account had been silent for the past four days, and had begun tweeting again minutes before it announced the attack. In its first message posted since Sept. 6, the account declared that it is operated by "the security leader of Anonymous," who is responsible for securing its Internet relay chat, operations and attacks.Colin Neagle covers emerging technologies, privacy and enterprise mobility for Network World. Follow him on\u00a0Twitter\u00a0@ntwrkwrldneagle\u00a0and keep up with the\u00a0Microsoft,\u00a0Cisco and\u00a0Open Source\u00a0community blogs. Colin's email address is email@example.com.