Coming to you - most dangerous PC bug yet

Computer users were warned last night about a new virus which launches an automatic attack.

Up to now most viruses have infected a PC only if the user opened an e-mail and then an attachment inside.

However, Netsky-V starts to infect the computer when the user clicks on the subject line of the e-mail.

Experts said the arrival of a worm of this type poses the greatest danger to home users, who are less likely than businesses to have the right anti-virus software installed.

Internet security firm Sophos first detected the worm on Wednesday. It has been found in e-mails with the subject lines mail delivery sytem (sic) failure, mail delivery failed, server system failure and gateway system failure. The first line of the e-mail contains messages such as 'converting message, please wait' and 'please wait while loading failed message'.

Sophos believes the virus could be intended to bring down file-sharing websites by using infected computers to launch a 'denial of service' attack.

Graham Cluley, of Sophos, said: 'If the worm was programmed to download the infection from a website, it would be easy to shut the site down.

'But it is using individual computers as virus factories to help it spread.'