In the last week, major American corporations affiliated with Wikileaks have been rushing to sever ties with the whistle blower site. First Amazon, whose servers hosted the website, bolted, then Paypal, MasterCard and Visa, who directed donations to the site. Critics of the companies say they were bowing to political pressures or perhaps preempting U.S. government retribution. What these firms may not have been anticipating is retribution from independent hacker squads. 

Over the last few days, an online activist group known as "Anonymous" has been carrying out "Operation: Payback," an orchestrated cyber attack against the firms who have abandoned WikiLeaks. Earlier this week, they are suspected of having taken down PostFinance, the Swiss postal service bank that froze WikiLeaks founder Julian Assange's account. Today, the group took down MasterCard's website for much of the day. These ambitious attacks have drawn the attention of a number of security writers and bloggers. Here's what they're saying:

  • Member of Anonymous Speaks Out  In an exclusive interview with the BBC, a member named Coldblood told the news organization about the hacker team's philosophy:

As an organisation we have always taken a strong stance on censorship and freedom of expression on the internet and come out against those who seek to destroy it by any means. We feel that Wikileaks has become more than just about leaking of documents, it has become a war ground, the people vs. the government.

  • This Is a Window into the Future of Activism, writes Kit Eaton at Fast Company:
These moves highlight that digital protests are getting smarter, and can potentially have significant effects on businesses capability to operate, in an age where more and more of our work is carried out online... Hack attacks are definitely the future of active protests. They're relatively easy to pull off, easy to participate in, and don't require leaving your desk if you're an activist.

  • MasterCard Brushes Off the Attack  "It is important to note that our systems have not been compromised and there is no impact on our cardholders' ability to use their cards for secure transactions globally," said the company in a statement issued Wednesday.
  • That's Not Actually True, counters John Oates at The Register: "The Reg has been contacted by merchants down under who are currently unable to access the payment portal on Mastercard's private network--a far more serious breach of security than just downing a website."
  • These Attacks Come at an Important Time for Credit Firms, writes Paul Mutton at Netcraft:
Although denial of service attacks are illegal in most countries, Operation Payback clearly has a sufficient supply of volunteers who are willing to take an active role in the attacks we have seen so far... Concurrent attacks against the online payment services of MasterCard, Visa and PayPal would have a significant impact on online retailers, particularly in the run up to Christmas.
  • Twitter Might Be the Next Target, writes Doug Aamoth at TechLand, explaining that the group "believes [Twitter] has censored certain tweets containing #wikileaks and #cablegate hashtags." But is that true?

The complaint was that the #wikileaks hashtag wasn't showing up in Twitter's list of popular, "trending" topics. Twitter has denied censoring WikiLeaks news, saying that its algorithm for detecting trending topics measures quick bursts of commonly-used hashtags rather than a high-volume of commonly-used hashtags over longer periods.

Update: ABC News reports that Sarah Palin's PAC has also fallen victim to "Operation Payback"