Cyber-extortionists are behind the distributed denial of service attack which has crippled the Million Dollar Homepage website created by 21 year-old British student Alex Tew. 

"MillionDollarHomepage.com has been subjected to a DDoS attack by malicious hackers who have caused the site to be extremely slow loading or completely unavailable since last Thursday," Tew wrote on his blog.

The website sold advertising space on a grid displaying a total of one million pixels at $1 per pixel. The site was launched in August and sold out on 13 January. The revenues are intended to fund Tew's university education.

Blackmailers at first asked for $5,000 to avert an attack on the site. The DDoS attack was launched after Tew declined to pay, and the hackers then demanded $50,000 to stop it.

A further refusal to pay prompted the attackers to deface the site on Wednesday, replacing the regular page with a message stating: 'Don't come back you sly dog!'.

Later on Wednesday the website was up again and appeared to be running normally.
In a DDoS attack a website receives a large amount of traffic from a series of computers. The rush typically causes the site to slow down or become completely unresponsive.

While online extortion is a common phenomenon, this case is special as attackers normally target online businesses such as stores or gambling sites.

"This time the attackers are targeting a private person because they know he has the money," said Mikko Hyppönen, chief research officer at security vendor F-Secure.