Anonymous - the hacktivist group that has become notorious for its DDoS attacks on websites of the RIAA, MPAA, and other anti-piracy organizations and companies - has taken it upon themselves to "defend" WikiLeaks.

Following the recent denials of service to the whistleblowing organization, they have turned their LOIC tool towards new targets: EveryDNS, PayPal, Mastercard, Visa, Swiss Bank Post Finance.

"While we don't have much of an affiliation with WikiLeaks, we fight for the same reasons," it says on their website - which has, accidentally, also apparently been hit by a DDoS attack and is down for the moment. "The attempts to silence WikiLeaks are long strides closer to a world where we can not say what we think and are unable to express our opinions and ideas. We can not let this happen."

This string of attacks has been executed using a botnet formed by computers of volunteers that have installed the so-called "Low Orbit Ion Cannon" - an application that allows users who don't know the first thing about hacking to participate in the attack by simply pushing a button. But, according to ComputerWorld, the attackers used another botnet which apparently doesn't consist of "volunteered" computers, but of computers roped into a botnet without the knowledge of their owners.

PayPal's blog was the first to be hit, but then the attackers turned their attention to the PayPal.com address. The site was rendered unavailable for some hours, but the company's spokesman says that that didn't affect payments. That is difficult to believe, since PayPal customers need to access the site in order to send money.

Mastercard and Visa depend less on their Internet presence, but they have been also affected by the attacks. Along with its official site, MasterCard's SecureCode service for secure online transactions has also been targeted by Anonymous - or at least so the group claims. Mastercard called the problems they've been experiencing "operational issues", and said they were resolved.

And, if what this tweet says is true, Visa's e-commerce engine has also been severely hit.