An update is available for the Microsoft Malware Protection Engine to control updates to the last access time stamp on scanned files

INTRODUCTION

This article describes a software update for Microsoft Malware Protection Engine. The update supports the disabling of updates to the last access time stamp on scanned files. This feature was introduced in the January 2009 version of the Malware Protection Engine that is included in definition version 1.51.2.0.

More Information

To disable last access time stamp updating during a scan, you must set an environment variable and restart the anti-malware service. To do this, follow these steps:

1. Right-click My Computer, and then click Properties.

2. • In Windows Vista or in Windows Server 2008, click Advanced System settings.

   • In Windows XP or in Windows Server 2003, click the Advanced tab.

3. Click Environment Variables.

4. Under System variables, click New.

5. In the Variable name box, type MP_DISABLE_LAST_ACCESS_TIME_UPDATE.

6. In the Variable value box, type 1, and then click OK.
   

7. Click OK two times to close all the dialog boxes.

8. Restart the anti-malware service:

   • For Forefront Client Security, follow these steps:

     1. Click Start, click Run, type services.msc, and then press ENTER.

     2. Right-click Microsoft Forefront Client Security Antimalware Service.

     3. Click Restart.

   • For Windows Defender, follow these steps:

     1. Click Start, click Run, type services.msc, and then press ENTER.

     2. Right-click Windows Defender.

     3. Click Restart.

   • For Microsoft Security Essentials, follow these steps:

     1. Click Start, click Run, type services.msc, and then press ENTER.

     2. Right-click Microsoft Protection Service.

     3. Click Restart.

When the Microsoft Malware Protection Engine scans a file during real-time protection or during an initiated scan, it will update the last access time stamp on the file. After the time stamp is updated, software that relies on the last access time stamp may not function as you want. Examples of this may include but are not limited to backup software, including unnecessary files in the archive set or indexing software rescanning files.

By default, the last access time stamp will continue to be updated as files are scanned.

You can disable this behavior in versions of the Malware Protection Engine that are included in the definitions that are equal to or greater than 1.51.2.0. You can receive detailed steps for changing the behavior by contacting Microsoft Customer Service and Support. For a complete list of Microsoft Customer Service and Support telephone numbers or to create a separate service request, visit the following Microsoft Web site:

http://support.microsoft.com/contactus/?ws=support