Melissa virus keeps software staff on alert

The fastest spreading computer virus on record will continue to cause problems for the rest of this week - at the least - as companies move to install anti-virus "patches".

Dublin-based anti-virus software company, Priority Data Solutions, said yesterday that its phones had been "ringing off the hook". According to Mr Alec Florence, Priority's group managing director, the company received 500 phone calls yesterday morning alone.

The Melissa virus set off on its destructive mission on Friday morning, and within 24 hours international companies with one personal computer or more were on alert. The virus spreads a list of pornography sites via email, and propagates in multiples of 50.

Mr Florence said: "We had around 20 large corporations report the virus this morning, and they came from sectors including industry, finance and government. There will be a lot of companies spending the evening scanning and cleaning their computers."

A number of Irish companies called in their technical staff over the weekend to protect their systems against the virus, and in cases where the damage was already done, set about fixing the problem. Most of the leading anti-virus software companies have come up with an antidote.

It is generally estimated a major virus outbreak can cost a mid-sized company around £15,000. "There is absolutely no doubt this is the worst virus ever, and it is the simplest virus to write. It's a piece of cake, written in Visual Basic," Mr Florence said.

The virus bears a winking smiley face symbol, and in the email subject field reads "important message from - ". The body of the message says "Here is that document you asked for ... don't show anyone else." Once opened the virus infects the normal Word document macro within Microsoft Word, and within e-mail packages Microsoft Outlook or Microsoft Express, the virus e-mails a copy of the infected document to the first 50 entries - including user groups - in the user's address box.

The effect of transmitting multiple messages simultaneously exerts pressure on any company server, and in this case, could bring the whole system down. According to Mr Kevin Street, a systems engineer with Symantec, anti-virus specialists, an organisation with around 10,000 employees could have 500,000 emails hitting its server at one time.

The virus is also programmed to display a message when the time of day matches the American date sequence, e g the message would appear at 3.30 a.m. today. The message reads "Melissa, written by KWYJIBO". This is acknowledged as a reference to an episode of the Simpsons where Bart used this word during a game of Scrabble, and tried to pass it off as an exotic bird.

A second virus, dubbed Papa, was yesterday described by Mr Sal Viveros of the California-based Network Associates as a "poorly written copycat" of Melissa. With Papa, when a user opens an infected e-mail, the virus is automatically extended to the first 60 addresses they detects in the user's computer. Each time a user reopens the infected document, the virus spreads.