A virus designed to attack the White House struck several Logic customers last week.

The "Code Red" virus is a worm that replicates in an internet-based server before dispatching its offspring to perform a "denial-of- service attack" against www.whitehouse.gov.

Ryan Permeh of eEye Digital Security, who discovered Code Red last week, said: "The worm's purpose, ultimately seems to perform a denial-of-service attack against www.whitehouse.gov."

The infection begins when the worm enters the computer and sets up 100 threads of itself.

One worm checks for English (US) Windows NT/2000 and if it finds the programme, it will deface Windows for ten hours with the sign "Hacked by Chinese!"

The other 99 worms will check for a programme called "notworm", which will keep the worm from spreading.

If the programme is not on the computer, the worm will check the computer's date and if past the 20th of the month, it will attack www.whitehouse.gov.

With so many attacks, the data would potentially amount to a denial-of-service.

If the computer's date is between the 1st and 19th of the month, the 99 worms will find and infect new Web servers.

Logic said: "The issue has been resolved and customers should no longer experience problems with their Internet service."