Yesterday morning, at around 8:15 AM, Internet “hacktivist” group Anonymous sent combined Distributed Denial of Service (DDoS) attacks to the site Mastercard.com, in response to the company’s decision to stop processing donations for the nonprofit organization WikiLeaks. This kind of attack consists in overwhelming a target with a barrage of communication signals, such that it cannot respond to legitimate site traffic. Anonymous’ attack was of such strength that it rendered the site frozen, preventing both the interface and its backdoor payment system, securecode.com, from functioning properly. The credit giant originally attempted to play down the attacks, stating originally that they were only experiencing “heavy traffic”, but later released this statement:

Please be advised that MasterCard SecureCode Support has detected a service disruption to the MasterCard Directory Server. The Directory Server service has been failed over to a secondary site however customers may still be experiencing intermittent connectivity issues. More information on the estimated time of recovery will be shared in due course.

There’s no questioning that the Mastercard site attack is a huge deal for Anonymous – the group’s biggest takedown yet in the Wikileaks saga — as well as a loud message to all other “secure” e-commerce sites worldwide: Mess with Wikileaks, and we’ll take you down.

PostFinance, the Swiss banking company that closed Wikileaks Editor-in-Chief/International Man of Mystery Julian Assange’s account (money for his legal defense fund) on Monday, was also a victim of the attacks (which it is still battling as of this writing), as was PayPal and EveryDNS (which stopped hosting the WikiLeaks site). Computerworld reports that the sites of former Alaska Governor Sarah Palin and current U.S. Senator Joseph Lieberman were also briefly taken down by the group. And the most recent target? The website of the Swedish prosecutor representing the two women accusing Assange of rape, molestation, and unlawful coercion. (The DDoS attack on their site was reported to the police, according to the Wall Street Journal.) And there’s speculation that Twitter, which has been accused of censoring #wikileaks and #cablegate from trending (an accusation it denies) and Amazon, which refused to host WikiLeaks documents, are next.

So who’s Anonymous, and why should we care?

A member of Anonymous, in traditional Guy Fawkes mask.

Birthed from the popular Internet forum 4chan, the massive, decentralized group prides itself on championing the free flow of information in the digital age. It has attacked those that persecute file-sharing sites (such as the RIAA and musician Gene Simmons), and the Church of Scientology, among others.

Calling the attacks “Operation: Payback,” they’ve expanded to develop “Operation: Avenge Assange.” Their mission statement for the operation is posted here: It encourages members and supporters to “get vocal” about the leaks, distribute cables, and protest. “The end goal is a Human DNS,” the message reads, “something that can only be stopped by shutting off the entire internet.”

Julian Assange

Julian Assange

Julian Assange

The Assange campaign is Anonymous’ most high-profile yet, and it doesn’t seem to be stopping soon — in fact, their energy seems to be spreading to other outlets. Other online supporters worldwide have responded to government condemnation of WikiLeaks by hosting hundreds of mirror sites, in the event that the main site is forcibly shut down. A Facebook event for a New York protest in support of the site has even been created recently. And with Assange now in a London jail fighting extradition to Sweden — with phone calls, but no internet — expect the support of his online friends to increase tenfold.