US market research firm, Computer Economics, has said the "I Love You" virus that swept around the world last week could cost those companies and organizations that were hit 'at least £1.75 billion'.

The eventual cost of the virus could be over £8 billion. Computer Economics estimates that more than 45 million email users received the virus. Though the virus does little damage to Macs, reports warn that as the Mac becomes more popular, the virus pool for the platform could also grow.

Pervasive Melissa, the highly publicized email worm unleashed last year, "pales in comparison to this virus", said Samir Bhavnani, an analyst at Computer Economics. The new virus "spread at such a speed" and led to a fast flurry of copycat viruses, said Bhavnani, who described the latest outbreak as "economic terrorism".

One user who experienced the speed and power of the "I Love You" virus is Linda Stewart, corporate data security administrator at Idaho Power in Idaho.

Stewart said her team detected the virus at 7:20 am on Thursday, May 4 and shut down the utility company's Internet and Exchange messaging servers by 7:45. But in that time, the virus had replicated itself throughout 1,800 mailboxes and into network files in the company's 90-PC server farm.

Ineffective "It was 100-fold, maybe 1,000-fold worse than Melissa," Stewart said. "We have four levels of virus protection, but because this made it into the wild so quickly, and everyone was so blindsided, none of the protective measures in place were effective."

Stewart said it's still too early to assess the long-term business fallout and what the virus cost Idaho Power. "But it is significant," she added.

Meanwhile, just as companies began to right their networks after the proliferation of love letters on Thursday, the problem was compounded with the appearance of a new strain of the virus, "Joke". Soon after that came the Baltic version of the virus, an email with the subject line "Let's have coffee together" in Lithuanian.

Source The "I Love You" virus-worm hybrid is believed to have been developed in the Philippines, because it caches network log-in passwords and sends them in a text file to an email address in that country. Philippine authorities are close to identifying the sender, CNN reported. Copycat virus versions that followed, were probably designed by other hackers.

The weekend saw another attack via email confirming a bogus Mother's Day gift order. The email included an invoice attachment, which recipients were asked to print. If they did, the virus overwrote files used in system start-up, making the computer difficult to reboot.

To protect their networks, many corporations, including Ford and Microsoft, shut down all or part of their email systems. The US Senate, the US Navy and the British House of Commons did the same.

At last count, the number of virus strains was up to eight, according to Carey Nachenberg, chief researcher at Symantec's antivirus research center in Santa Monica, California. More could be on the way.

"We've made a compromise between functionality and security, and functionality won out," says Nachenberg, who points out that virus-worms are "not rocket science", illustrating how vulnerable corporate computer systems are to even the simplest viruses.