Mensaje de correo de Microsoft

Hoy he recibido un mensaje de de correo de Microsoft, con este asunto
"Latest Internet Security Pack" y un adjunto llamado "patch.exe" de 156 KB.
Me mosquea mucho y no se si es autentico. Por lo pronto no pienso ejecutar
el adjunto ni en broma.
El texto lo pego aquí:

Microsoft Customer

this is the latest version of security update, the
"September 2003, Cumulative Patch" update which eliminates
all known security vulnerabilities affecting Internet Explorer,
Outlook and Outlook Express as well as five newly
discovered vulnerabilities. Install now to protect your computer
from these vulnerabilities, the most serious of which could allow
an attacker to run executable on your system. This update includes
the functionality of all previously released patches.

System requirements Win 9x/Me/2000/NT/XP
This update applies to Microsoft Internet Explorer, version 4.01 and
later
Microsoft Outlook, version 8.00 and later
Microsoft Outlook Express, version 4.01 and later
Recommendation Customers should install the patch at the earliest
opportunity.
How to install Run attached file. Click Yes on displayed dialog box.
How to use You don't need to do anything after installing this item.

Microsoft Product Support Services and Knowledge Base articles
can be found on the Microsoft Technical Support web site.
For security-related information about Microsoft products, please
visit the Microsoft Security Advisor web site, or Contact us.

Please do not reply to this message. It was sent from an unmonitored
e-mail address and we are unable to respond to any replies.

Thank you for using Microsoft products.

With friendly greetings,
MS Corporation Network Security Department

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©2003 Microsoft Corporation. All rights reserved. The names of the actual
companies
and products mentioned herein may be the trademarks of their respective
owners.