18.4.8 Ensure 'MSS: (SafeDllSearchMode) Enable Safe DLL search mode (recommended)' is set to 'Enabled'

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Information

The DLL search order can be configured to search for DLLs that are requested by running processes in one of two ways:

Search folders specified in the system path first, and then search the current working folder.

Search current working folder first, and then search the folders specified in the system path.

When enabled, the registry value is set to 1. With a setting of 1, the system first searches the folders that are specified in the system path and then searches the current working folder. When disabled the registry value is set to 0 and the system first searches the current working folder and then searches the folders that are specified in the system path.

Applications will be forced to search for DLLs in the system path first. For applications that require unique versions of these DLLs that are included with the application, this entry could cause performance or stability problems.

The recommended state for this setting is: Enabled.

Note: More information on how Safe DLL search mode works is available at this link: Dynamic-Link Library Search Order - Windows applications | Microsoft Docs

Rationale:

If a user unknowingly executes hostile code that was packaged with additional files that include modified versions of system DLLs, the hostile code could load its own versions of those DLLs and potentially increase the type and degree of damage the code can render.

Impact:

None - this is the default behavior.

Solution

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

Computer Configuration\Policies\Administrative Templates\MSS (Legacy)\MSS: (SafeDllSearchMode) Enable Safe DLL search mode (recommended)

Note: This Group Policy path does not exist by default. An additional Group Policy template (MSS-legacy.admx/adml) is required - it is available from this TechNet blog post: The MSS settings - Microsoft Security Guidance blog

Default Value:

Enabled.

See Also

https://workbench.cisecurity.org/files/3458

Item Details

References: CSCv6|8, CSCv7|8.1, CSCv7|8.2

Plugin: Windows

Control ID: 761b05a368148598fabe03bb944519cc90b0e631659f3b2e19bc08d1317ecd98