This article describes why the Worm list is not updated as frequently as the antivirus scan engines are updated in Microsoft Antigen, in Microsoft Forefront Security for Exchange Server, and in Microsoft Forefront Security for Office Communications Server.
The definitions in the Worm list differ from the definitions that are used by the antivirus scan engines. The Worm list includes generic worm name entries. These entries may help provide protection against future worms that are part of a worm family that has already been detected.
For example, if a new worm that is called "Win32/abcdef.A@mm" is detected, Antigen, Forefront Security for Exchange Server, and Forefront Security for Office Communications Server update the Worm list to include a generic entry such as "*abcdef*". This entry covers any new variant of the same virus, such as Win32/abcdef.M@mm. Because the Worm list contains generic worm name entries, the Worm list does not have to be updated as frequently as the antivirus scan engines are updated.