W32.Navidad is a mass-mailing worm program. Using MAPI, the worm replies to all inbox messages that contain a single attachment. This worm is able to distribute itself through any MAPI-compliant email client, including Microsoft Outlook. However, email messages that are infected with this worm can be received by any email client. The worm utilizes the existing email subject line and body and attaches itself as Navidad.exe. Due to the bugs in the code, when the worm is executed, it causes your system to be unusable.
Symantec has also created an interactive tutorial
to help you get rid of this worm.
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