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18.5.14.1 (L1) Ensure 'Hardened UNC Paths' is set to 'Enabled, with 'Require Mutual Authentication' and 'Require Integrity' set for all NETLOGON and SYSVOL shares' - SYSVOL

Information

This policy setting configures secure access to UNC paths.
The recommended state for this setting is:

Enabled, with 'Require Mutual Authentication' and 'Require Integrity' set for all NETLOGON and SYSVOL shares.

Note: If the environment exclusively contains Windows 8.0 / Server 2012 (non-R2) or newer systems, then the 'Privacy' setting may (optionally) also be set to enable SMB encryption. However, using SMB encryption will render the targeted share paths completely inaccessible by older OSes, so only use this additional option with caution and thorough testing.

Rationale:
In February 2015, Microsoft released a new control mechanism to mitigate a security risk in Group Policy as part of the MS15-011 / MSKB 3000483 security update. This mechanism requires both the installation of the new security update and also the deployment of specific group policy settings to all computers on the domain from Windows Vista / Server 2008 (non-R2) or newer (the associated security patch to enable this feature was not released for Server 2003). A new group policy template (NetworkProvider.admx/adml) was also provided with the security update.

Once the new GPO template is in place, the following are the minimum requirements to remediate the Group Policy security risk:

\\*\NETLOGON RequireMutualAuthentication=1, RequireIntegrity=1
\\*\SYSVOL RequireMutualAuthentication=1, RequireIntegrity=1

Note: A reboot may be required after the setting is applied to a client machine to access the above paths.

Additional guidance on the deployment of this security setting is available from the Microsoft Premier Field Engineering (PFE) Platforms TechNet Blog here: Guidance on Deployment of MS15-011 and MS15-014.

Solution

To establish the recommended configuration via GP, set the following UI path to Enabled with the following paths configured, at a minimum:

\\*\NETLOGON RequireMutualAuthentication=1, RequireIntegrity=1
\\*\SYSVOL RequireMutualAuthentication=1, RequireIntegrity=1

Computer Configuration\Policies\Administrative Templates\Network\Network Provider\Hardened UNC Paths

Note: This Group Policy path does not exist by default. An additional Group Policy template (NetworkProvider.admx/adml) is required - it is included with the MS15-011 / MSKB 3000483 security update or with the Microsoft Windows 10 RTM (Release 1507) Administrative Templates (or newer).

Impact:
Windows only allows access to the specified UNC paths after fulfilling additional security requirements.

Default Value:
Disabled. (No UNC paths are hardened.)

See Also

https://workbench.cisecurity.org/benchmarks/14249

Item Details

Category: RISK ASSESSMENT

References: 800-53|RA-5, CSCv6|3, CSCv7|3.1

Plugin: Windows

Control ID: bcbf7cfc312e4c604e953ecc3e1ac08ba86276fc925dcd9be972b5fa8f736b15