Latest pre-release definition version: 1.219.658.0
Microsoftoffers partially-tested pre-release definition updates for download before the fully-tested (released) version is available. These updates are listed below.
You can use these pre-release definitions to clean infected computers. You can also use them to protect computers that are at an immediate risk of infection. The pre-release definition update is not meant for enterprise-wide deployment.
Pre-release updates are explicitly created for malicious software threats. You should not deploy a pre-release definition update if you are not experiencing a threat for which it was explicitly created.
Note: After additional testing, certain pre-release definition updates will be released as regular definition updates. The same binary file that was used for the pre-release definition update may be used for the released definition update.
The following procedure outlines how to install a pre-release definition update.
Before you begin, you must establish whether your computer is running a 32-bit version or a 64-bit version of Windows. If you are unsure what version your computer is running, refer to the following link: How to determine whether a computer is running a 32-bit version or 64-bit version of the Windows operating system (KB827218)
Click on the link that applies to your computer:
Microsoft Antimalware products including
Microsoft Forefront products or
Microsoft Security Essentials:
Microsoft Antispyware products including
If you want to use the command-line switch to install the update in quiet mode (this suppresses the file extraction dialog box), type the following command:
Note: To run this command, you must use an account that has administrator rights.
Regular definition updates are available if you subscribe to the automatic definition update mechanism in the next regularly scheduled release. You can also choose to manually update your definition library.
The latest definition updates are always available for download on our latest definitions page.
I want to...