1.3.1 (L2) Ensure 'Allow read access via the File System API on these sites' is set to 'Disabled'

Information

This policy setting allows organizations to list the URL patterns that specify which sites can ask users to grant them read access to files or directories in the host operating system's file system via the File System API.

The recommended state for this setting is: Disabled

Note: Leaving this policy not configured allows the _DefaultFileSystemReadGuardSetting (Control use of the File System API for reading) to apply for all sites. This setting is configured in the Level 2 profile:

Ensure 'Control use of the File System API for reading' is set to 'Enabled: Don't allow any site to request read access to files and directories'

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Note #2: URL patterns can't conflict with _FileSystemReadBlockedForUrls (Block read access via the File System API on these sites). Neither policy takes precedence if a URL matches with both.

This API allows web apps to read or save changes directly to files and folders on user devices. It also allows for the reading and writing files and the File System Access API provides the ability to open a directory and enumerate its contents.

Allowing web apps the ability to enumerate the contents of a directory by reading or saving changes directly to files and folders opens the organization to the possibility of malicious content being saved directly to user devices.

Solution

To establish the recommended configuration via GP, set the following UI path to Disabled :

Computer Configuration\Policies\Administrative Templates\Microsoft Edge\Content settings\Allow read access via the File System API on these sites

Note: This Group Policy path may not exist by default. It is provided by the Group Policy template MSEdge.admx/adml that can be downloaded from:

Download Microsoft Edge for Business - Microsoft

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Impact:

Users with creative roles that require read access to files and directories via the File System API may need additional permissions granted for said roles.

See Also

https://workbench.cisecurity.org/benchmarks/18501

Item Details

Category: CONFIGURATION MANAGEMENT, SYSTEM AND COMMUNICATIONS PROTECTION

References: 800-53|CM-10, 800-53|CM-11, 800-53|SC-18, CSCv7|7.2

Plugin: Windows

Control ID: 9cc6d3bab10d9672cc5e06425805ae7c9048ae973c392e4f802f46b5238ae4ad