A rapidly spreading computer virus forced several large corporations to shut down their e-mail servers Friday night as the virus rode the Internet on a global rampage, several leading network security companies reported Saturday.
The companies said early reports of the virus, which is carried by e-mail, led them to believe that tens of thousands of home and business computers had been infected on Friday alone. The virus reproduces itself exponentially, they said, trying to use each infected message to send 50 more infected messages.
Network security experts said the virus appears to do no harm to the machines it infects and that individuals could easily disable it. But they said its purpose is to interrupt networks by replicating itself so rapidly that it overwhelms networks and e-mail servers.
E-mail infected with the virus, which its creators call Melissa, has a topic line that begins “Important Message From.” Next is the sender’s name, which is often the name of someone known to the recipient.
The message within the e-mail is short and innocuous: “Here is that document you asked for . . . don’t show anyone else ;-)” Attached to it is a 40,000-byte, or 40K, Microsoft Word document named list.doc.
When the recipient opens list.doc, the Melissa virus automatically searches for an e-mail address book. It then sends a copy of itself–the message and attachment–from the recipient to the first 50 names it finds in the recipient’s address book, which accounts for the rapid acceleration across the Internet.
The virus is known to spread rapidly with two popular e-mail programs, Microsoft Outlook and Microsoft Outlook Express.
Network security administrators said they had seen no evidence that Melissa could open and use the address books in other e-mail programs, but they did not rule out the possibility.
Several anti-virus software makers posted software on their Web sites that their customers can download to detect the virus-encoded message and refuse it. A fix for the general public is available on the Web site of Sendmail Inc. (www.sendmail.com).
Sendmail’s post-office software often is used to direct mail on the Internet.
