SVCHOST Versions

The SVCHOST.EXE program appears only in NT versions of Windows. It dates from Windows 2000, when it developed from code that was previously in SERVICES.EXE. It has progressed through minor versions for each new Windows package until a change of major version for Windows Vista.

This progression is mostly orderly, in the sense that support for a feature depends just on the major and minor version numbers, but there are exceptions, such that it can matter to know which build is being worked with. Some features start from a particular build number within a version, and are then supported in higher versions. Some have more complicated histories, where a feature is added for late builds of two versions, and is then supported in higher versions.

Builds

The following builds have been inspected for these notes. Most are from MSDN discs. Some, especially since Microsoft greatly reduced its shipment of operating systems on MSDN discs, are from service packs downloaded (typically as self-extracting executables) from a Microsoft website.

Builds are arranged in increasing order of the file version as recorded in the executable’s resources. This version number is readily visible using Windows Explorer either in a so-called infotip for the file or by accessing the Version tab in the Properties dialog for the file. Programmers know this version number as coming from the so-called root block of the version-information resource, specifically from the dwFileVersionMS and dwFileVersionLS members of a VS_FIXEDFILEINFO structure.

The date stamp shown for each version is more obscure. File dates are easily modified after the executable is built and are anyway liable to be shown differently when read from different time zones. However, there is in each executable’s header a date stamp which is set when the executable is built and which is not commonly changed afterwards. It is readily accessible to anyone with programming knowledge and appropriate tools, e.g., Microsoft’s own DUMPBIN utility.

There seems to be no SVCHOST.EXE in Windows 2000 Service Packs 1 to 4 inclusive. The binaries distributed with the original Windows XP and Service Pack 1 are identical.