Hackers launch cyber war on Amazon, Palin – and Sweden

The online cyber war being waged against companies that have refused to host WikiLeaks or process donations to the whistle-blowing website intensified dramatically yesterday.

In a vivid illustration of the volatile nature of the internet, websites perceived to be anti-WikiLeaks were struck by attacks – among them Amazon, Paypal, Sarah Palin, the US State Department and the Swedish Government.

The renewed cyber assaults by members of the shadowy hacker group "Anonymous" came after the disruption on Wednesday of the payment systems for Visa and Mastercard, both of which recently declined to process donations to WikiLeaks.

Anonymous, a shadowy and highly decentralised collective of cyber activists who vote on who to target through message boards, recruited an army of volunteers to attack websites that have recently disassociated themselves from WikiLeaks in an action called "Operation Payback".

By last night some 31,000 people had downloaded special software allowing them to target their perceived opponents with distributed denial of service attacks (DDoS), a relatively simple way of slowing down or temporarily closing a website by flooding it with requests for information. The software allows computers to join a botnet – a large collection of machines that use their combined power to target one website at a time with millions of "hits".

Usually DDoS attacks are launched by computers hijacked by a virus or malicious code. But the Anonymous botnet, which activists call a "low orbit ion-cannon" in a geeky nod to sci-fi films, is a voluntary network.

Websites with good security and bandwidth like Amazon should be able to withstand all but the largest botnet attacks. But others, such as Sarah Palin's website, Paypal and the Swedish government's homepage, were apparently disrupted.

Knowingly taking part in a DdoS attack is illegal in the UK and could land users with a two-year jail sentence, but it is believed that numerous Anonymous volunteers come from Britain.

The renewed attacks came as WikiLeaks yesterday released its first public comments on Anonymous.

"We neither condemn nor applaud these attacks," said WikiLeaks spokesperson Kristinn Hrafnsson. "We believe they are a reflection of public opinion on the actions of the targets." A statement added: "[Anonymous] group is not affiliated with WikiLeaks. There has been no contact between any WikiLeaks staffer and anyone at Anonymous. WikiLeaks has not received any prior notice of any of Anonymous' actions."

Hours before, the UN's top human rights official criticised websites that have refused to host WikiLeaks, suggesting it breached the platform's right to freedom of expression.

High Commissioner for Human Rights Navi Pillay told reporters in Geneva yesterday that the moves "could be interpreted as an attempt to censor the publication of information". Over the past 48 hours Anonymous has been able to call the shots on who to target. But there have been some reprisal attacks on websites popular with hacktivist networks. Those most likely to be behind such counter attacks are thought to be the kind of "freelance patriot" American hackers that first launched attacks on Wikileaks two weeks ago, sparking an online information war that has grown each day.

Facebook and Twitter tried yesterday to close down support pages for the Anonymous network, after reports emerged that personal credit card details were being posted online. Activists simply created new support sites under different names, forcing Facebook and Twitter to engage in what one blog described as an online "whack-a-mole" contest.

The Anonymous network then called on its activists to target Amazon, which last week kicked WikiLeaks on one of its website services.

The argument appeared to halt a concerted assault on Amazon but Anonymous scored a moral victory by spreading the word that the retailer was selling a downloadable version of the WikiLeaks State Department cables for its Kindle e-reader.