Update Microsoft antivirus and antispyware products

This page contains links to the latest antimalware and antispyware definitions. You can update your Microsoft security software by downloading these definitions.

Latest definitions

For antimalware and antispyware: 1.155.970.0, Jul 28, 2013 04:12 PM UTC

Links to the latest definition updates for Microsoft security products

Antimalware and antispyware definitions

The following table presents links for the latest antimalware and antispyware definitions for Microsoft security software.
For the software that you have installed on your computer, choose either 32-bit or 64-bit depending on the version of Windows on your computer.
To determine your version of Windows:

Open the Start menu or Start screen, type Computer, and press Enter.
On the left side of the File Explorer window that appears, right-click or tap and hold Computer, and then click or tap Properties.

Your version will be shown under System type.
To find out which product is best for you, visit the page What Microsoft security software is right for me?

	Antivirus and antispyware definitions (choose either 32-bit or 64-bit depending on your computer)
Microsoft Security Essentials	32-bit \| 64-bit
Windows Defender in Windows 8	32-bit \| 64-bit \| ARM
Windows Defender in Windows XP through 7	32-bit \| 64-bit
Microsoft Diagnostics and Recovery Toolset (DaRT)	32-bit \| 64-bit
Forefront Client Security	32-bit \| 64-bit
Forefront Server Security	32-bit \| 64-bit
Forefront Endpoint Protection	Visit this link
System Center 2012 Configuration Manager	Visit this link
System Center 2012 Endpoint Protection	Visit this link
Windows Intune	Visit this link

Network Inspection System definitions

For Microsoft Security Essentials, Forefront Endpoint Protection, and System Center 2012 Endpoint Protection, you can also download Network Inspection System (NIS) definitions. These definitions are designed to protect you from exploits and network infections.
There are two types of NIS definitions that you must download, depending on the version of your Microsoft security software.
To determine your version of Microsoft security software:

Open your security software by double clicking on the icon in the system tray (you may need to click the arrow to see the icon) or, in Windows 8, Search for Windows Defender:
Click the arrow next to Help and choose About <Software name>:
Your software version number is displayed at the line labelled Antimalware Client Version If you have a version number of 4.1.522.0 and above, you must download the Network Realtime Inspection definitions:
- For 32-bit versions of Windows, download 32-bit Network Realtime Inspection definitions
- For 64-bit versions of Windows, download 64-bit Network Realtime Inspection definitions
If you have a version number lower than 4.1.522.0, you must download the Network Inspection Service definitions:
- For 32-bit versions of Windows, download 32-bit Network Inspection Service definitions
- For 64-bit versions of Windows, download 64-bit Network Inspection Service definitions