Plan block file format settings in the 2007 Office system

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Topic Last Modified: 2016-11-14

Block file format settings prevent users from opening or saving specific file types and file formats in Microsoft Office Excel 2007, Microsoft Office PowerPoint 2007, and Microsoft Office Word 2007. The only block file format setting that is configured by default is the Block opening of files before version setting. This setting prevents users from opening Office Word 2007 files that have been saved in a format that is earlier than the Word 6.0 format. Files that have been saved using a beta version of Word 6.0 are considered to be earlier than the Word 6.0 format and cannot be opened by default. You can use block file format settings to help:

• Enforce file type and file format requirements in your organization.

• Manage file usage during and after a migration.

• Mitigate security threats that target specific file types and formats.

There are two types of block file format settings: block open settings and block save settings. Block open settings prevent users from opening various file types and formats; block save settings prevent users from saving files in various file types and formats.

The following table lists file types and file formats that are blocked by each block open setting. The file name extensions that are listed are not a complete list of the file types and formats that are blocked by a specific setting. The table lists file name extensions for the most common examples of the file types and formats that are blocked.

For a detailed description of each block open setting, see "Block file format settings" in Security policies and settings in the 2007 Office system.

The following table lists the file types and file formats that are blocked for each block save setting. The file name extensions listed are not a complete list of the file types and formats that are blocked by a specific setting. The table lists file name extensions for the most common examples of the file types and formats that are blocked.

For a detailed description of each block save setting, see Security policies and settings in the 2007 Office system.

When a user attempts to open a file type or file format that is blocked, the block file format mechanism evaluates the file at the parser level (when the file is loading), which provides a more thorough determination of file type and format than simple file-name extension checking. Because of this, changing the file name extension on a file will not affect the blocking mechanism. For example, if a file is saved in the Word 2003 binary format with a .doc extension, and you rename the file so that the extension is .rtf, any setting that blocks the opening of Word 2003 binary files will prevent users from opening the file even though it has an .rtf extension.

When a user attempts to save a file by using a file type or file format that is blocked, an error message appears. The error message explains that you are attempting to save a file that has been blocked by a system administrator. The error message also provides a link to the following Microsoft Knowledge Base article: You receive an error message when you try to open or save a file in one of the 2007 Office programs or in one of the Office 2003 programs (https://go.microsoft.com/fwlink/?LinkId=79656\&clcid=0x409).

Keep the following overall considerations in mind as you plan your block file format settings. These considerations apply any time you use block file format settings.

• You can configure block file format settings only for Office Excel 2007, Office PowerPoint 2007, and Office Word 2007 files.

• Block save settings can be configured only through Group Policy. You cannot use the Office Customization Tool (OCT) to configure block save settings.

• Most block open settings can be configured only through Group Policy. There is one block open setting that can be configured by using the OCT.

• Block open settings do not apply to files that are opened from trusted locations.

• Block file format settings are application-specific. You cannot prevent users from using other applications to open or save file types or formats that are blocked. For example, you can enable block file format settings that prevent users from opening .dot files in Office Word 2007, but users will still be able to open .dot files with Microsoft Office Publisher 2007, which uses a converter to read the .dot file.

• Disabling notifications in the Message Bar has no effect on block file format settings. The block file format warning dialog box appears before any notification appears in the Message Bar.

Although you can use block file format settings to manage file usage in many scenarios, these settings are most commonly used to:

• Force an organization to use the new file formats that are included in the 2007 Office system.

• Mitigate zero-day security attacks by temporarily preventing users from opening specific types of files.

• Prevent an organization from opening files that have been saved in earlier Office Word formats.

• Prevent an organization from using pre-release (that is, beta) file formats.