A new computer worm called MyDoom is spreading across the internet via spam emails and is threatening to become one of the most destructive computer infections ever, the anti-virus and anti-spam specialist Sophos warned today.
The worm - which has a number of aliases, including Novarg and Shimgapi - first appeared on Monday afternoon and targets computers running Microsoft Windows with any email program.
It opens a backdoor onto infected computers to allow hackers to gain access.
According to the anti-virus company mi2g, the MyDoom worm became the 21st worst infection ever within the first 24 hours of its existence. It spread quickly enough for most of the major anti-virus companies to rate it a "high" outbreak.
"MyDoom is unlike many other mass-mailing worms we have seen in the past, because it does not try to seduce users into opening the attachment by offering sexy pictures of celebrities or private messages," said Graham Cluley, a senior technology consultant for Sophos.
"MyDoom can pose as a technical-sounding message, claiming that the email body has been put in an attached file. Of course, if you launch that file you are potentially putting your data and computer straight into the hands of hackers," he said.
"Mailboxes at large corporations are infected and reporting multiple infections throughout their entire organizations," David Perry, the global education director at anti-virus experts Trend Micro Inc, told Reuters.
MyDoom arrives as an email attachment with an .exe, .scr, .zip or .pif extension. The most common attachment type appears to be .zip, experts said, a .zip file being a widely-used, compressed file format used to send and store large files.
Emails may arrive with "test" or "status" in the subject line, and may contain text, which reads: "The message cannot be represented in 7-bit ASCII and has been sent as a binary attachment."
The computer security firm Central Command confirmed 3,800 infections within 45 minutes of initial discovery.
"This has all the characteristics of being the next big one," said Steven Sundermeier, the company's vice-president of products and services.
Users who receive the worm and simply ignore or delete it will be able to avoid any damage.
