Overview of Windows 7 Update Files

Windows 7 uses MSU files for installing updates, which are Microsoft Update Standalone Packages. MSU files are not executable as are updates for versions of Windows prior to Windows Vista. However, they function quite similarly to executable files because you can double-click them to install an update.

Security Alert For security purposes, MSU files should be treated as executable files. Therefore, if you block executable files as e-mail attachments, you should also block MSU files.

MSU filenames have the following format:

<WindowsVersion>-KB<ArticleNumber>-[v<VersionNumber>-]<Platform>.MSU

The version number is listed only if an update is re-released with a version number higher than 1. For example, version 1 of a 32-bit Windows 7 update can be named Windows6.1-KB961367-x86.MSU. The 64-bit version of the same release of that update would be named Windows6.1-KB961367-x64.MSU. The following list describes each of these placeholders:

• WindowsVersion The version of Windows to which the update applies. For Windows 7, this is Windows 6.1.
• ArticleNumber The Microsoft Knowledge Base article number that describes the update. You can look up the article at http://support.microsoft.com/kb/<ArticleNumber>. For example, if the update filename is Windows6.1-KB961367-v1-x86-ENU.MSU, you can look up the supporting Knowledge Base article at http://support.microsoft.com/kb/961367.
• VersionNumber Occasionally, Microsoft might release multiple versions of an update. Typically, the version number will be 1.
• Platform This value will be x86 for 32-bit operating systems, x64 for 64-bit versions of Windows, and ia64 for Itanium-based computers.

Standardized naming for updates simplifies update processing by allowing you to evaluate updates from a script using only the filename.