Playing on consumer fears about the Year 2000 technology problem, one such message, known as the Y2Kcount.exe, falsely appears to be coming from Support@microsoft.com and has already been maliciously distributed to Microsoft customers through email, the company said.
Unsuspecting consumers who open the email message and execute the attachment may cause their computers to be vulnerable to the virus, Microsoft executives warned.
"The Y2K-related email message that claims to come from Microsoft is a hoax. Consumers should not open the attachment but rather delete it immediately," Don Jones, director of Year 2000 Readiness at Microsoft, said in a statement.
As many as eight different versions of the malicious email message are thought to be in circulation.
The Redmond, Washington-based software giant advises those looking to make certain their computers are ready for the Y2K date rollover to use the legitimate tools available at Microsoft's Y2K Web site, or the Microsoft Year 2000 Resource CD.
Microsoft said if it does send email messages to its customers regarding Y2K updates or security patches, it is solely to inform them that they are available and will only provide links to the Microsoft download sites. The company never attaches the software itself to the respective email.