Antivirus software maker McAfee warned that a defect in one of its products could make users computers vulnerable to attacks in which hackers use their computers to distribute spam.

The company, a subsidiary of chipmaker Intel, said the problem in a message to clients released on Wednesday on its Web site.

Ian Bain, a spokesman for Microsoft, said at least one client was a victim of this type of attack that exploits a flaw in a company’s service is known as SaaS McAfee Total Protection.

The Web-based service protects users from viruses hidden in emails and websites. Bain said that the defect was part of the portion of the software that McAfee customers need to install on their machines so they can use the service.

Although the defect may have allowed the use of machines for SaaS customers McAfee Total Protection for sending spam, the problem does not allow access to data stored on computers, said Bain.

He said the company’s engineers were working to correct the defect, and that should solve the problem until this Thursday.

In April 2010, a defect in a regular update of McAfee antivirus software mistakenly identified a part of the code of the popular Windows XP operating system such as viruses, which caused paralysis on the computers of many of its customers, including over 100 major companies .