Computer virus to attack again today, experts warn

Computer experts are warning users of a second wave of attacks this weekend from a computer virus that has already infected up to 100 million terminals.

The Sobig.F virus is expected to hit at 8pm today, causing maximum damage to companies when they are least prepared to deal with the bug. The secret file implanted on infected computers has already resulted in email disruptions at businesses and universities around the world.

Users contract the Sobig virus, being sent at a rate of one million copies a day, when they click on attachments to email lines such as "Details", "Approved" and "Thank you!".

Last week, security experts said they contained an attack of the virus by identifying and blocking 19 out of 20 sites that were at risk.

The virus was programmed to direct PCs to download files from a website between 8pm and 11pm on Friday but only visited a pornography site at the appointed time.

Carole Theriault, a consultant at anti-virus firm Sophos, said the virus, which has been clogging inboxes with unwanted messages, was showing no signs of slowing down. "It's really good news [that Friday's strike failed]," Ms Theriault said.

"However, there is a similar danger time between 8pm and 11pm on Sunday."

The virus causes havoc by triggering infected computers to download a contaminated programme from one of 20 servers which the hackers are believed to have already broken into and corrupted.

The virus writers who created Sobig are believed to be motivated by money.

Their aim is to cash in on finding better ways of sending out unwanted commercial email known as spam.