File Block Functionality is a little known security feature implemented into version 2003 and 2007 of the Microsoft Office System. The Redmond Company wanted to fix the notoriety aspect on May 21, concomitantly with announcing the availability of the Microsoft Office Isolated Conversion Environment. File Block Functionality was designed to deliver an extra barrier of protection to Office 2003 and Office 2007 users when handling potentially malicious documents.

Unlike MOICE's additional mitigation technologies associated with the file format converters between the 2007 and 2003 editions of the Office productivity suite, File Block is a mechanism offering control over the usage of Office file types. Specific documents can be blocked from being executed.

"The File Block Functionality for Microsoft Office 2003 and the 2007 Microsoft Office system allows administrators to restrict via registry and Group Policy specific Office file types that can or cannot be opened when using Microsoft Word, PowerPoint, and Excel. Blocking specific Office file types allows administrators to temporarily deny users the ability to open certain files, such as when a threat of attack from a given Office file type exists," Microsoft revealed.

Microsoft has made available a total of three Knowledge Base articles dealing with the File Block Functionality. 922849, 922848 and 922847 will reveal the actions that users need to take in order to resolve error messages that have been generated due to File Block. Office 2003 and 2007 users which no longer have the ability to open Word, Excel and PowerPoint documents will be able to find out how to recuperate their files.

The impossibility to execute Word, Excel and PowerPoint documents in the context of error messages pointing to issues related to the registry policy setting, is connected to File Block. Just access the Microsoft KB articles in order to understand how to modify the Windows registry in order to fix the problem.