Update: Dutch authorities have reportedly arrested a 16-year-old they claim is connected to 'Anonymous'

Is the world witnessing its first wave of digital sit-ins?

A group of "hacktivists" calling themselves "Anonymous" has been waging an "all-out cyber war" the last several days against corporate and public entities that have acted to censor secrets website WikiLeaks. They disrupted Visa and MasterCard transactions on Wednesday, bringing down websites for the world's two largest credit card providers. They stopped a Swiss bank from doing business and even knocked websites for a US Senator and former governor offline, with yet more attacks promised.

All of it -- or at least most, they insist -- is part of a voluntary campaign of cyber disobedience, to ensure these powerful entities know their actions are unpopular. Using a piece of software called "Low Orbit Ion Cannon," named after a weapon in the PC strategy game "Command and Conquer," volunteers can point their computers at a domain and begin saturating any server with traffic. If enough people join in, the site inevitably falls.

Their next target: Amazon.com. After announcing plans to blast the site with gobs of traffic, effectively denying page-loads to its regular customers, Amazon's share price on the New York Stock Exchange (symbol: AMZN) began to plummet, down 1.17 percent by 12:10 pm eastern. The site still appeared to be online.

Update: The company's stock staged a small rally later in the day when the site did not go down. It closed at less than 1 percent off the day's opening price.

Amazon was being targeted because the site took WikiLeaks off its cloud servers after being pressured to do so by staff for Sen. Joe Lieberman (I-CT), who also saw his web operation taken down by "Anonymous." WikiLeaks founder Julian Assange said they'd moved the site to Amazon to test its commitment to free speech following a cyber-attack that took down their Swiss servers.

"Anonymous" also targeted online payments leader PayPal, owned by California-based eBay, taking the site offline intermittently early Thursday. Service to PayPal.com was intermittent at time of this writing.

PayPal's blog had been previously been taken offline by denial of service attacks after the firm froze one of WikiLeaks' accounts. It claimed to have released WikiLeaks' money on Wednesday night.

Attempting to explain their actions, PayPal Vice President Osama Bedier told a European audience that the US State Department had informed the company that WikiLeaks was engaging in illegal activities. That turned out to be untrue: the State Dept. never sent them such a letter -- it was directed to WikiLeaks -- and the alleged crime was committed not by the media organization, but by the individual who stole the information.

The "Anonymous" group, which uses a headless man in a black suit as its insignia, reveled in the digital mayhem they've caused, joking on Twitter mid-morning that they'd sold shares in Amazon to buy new suits.

The night prior, Twitter moved to ban an account that had been helping direct the voluntary botnets being led against some of the world's most hardened server farms, after "Anonymous" hackers claimed to have posted a list of 10,000 MasterCard numbers with expiration dates. A MasterCard spokesman told Raw Story the numbers weren't theirs. Many of the numbers on the list began with a '4', which is what all Visa accounts start with. It was unclear whether the card numbers were genuine or not.

WikiLeaks issued a statement Thursday saying they were in no way affiliated with or connected to "Anonymous."

"We neither condemn nor applaud these attacks," WikiLeaks spokesman Kristinn Hrafnsson said in a media advisory. "We believe they are a reflection of public opinion on the actions of the targets."