Title

Windows Server 2019 permissions for the system drive root directory (usually C:\) must conform to minimum requirements. (Cat II impact)

Discussion

Changing the system's file and directory permissions allows the possibility of unauthorized and anonymous modification to the operating system and installed applications. The default permissions are adequate when the Security Option "Network access: Let Everyone permissions apply to anonymous users" is set to "Disabled" (WN19-SO-000240). Satisfies: SRG-OS-000312-GPOS-00122, SRG-OS-000312-GPOS-00123, SRG-OS-000312-GPOS-00124

Check Content

The default permissions are adequate when the Security Option "Network access: Let Everyone permissions apply to anonymous users" is set to "Disabled" (WN19-SO-000240). Review the permissions for the system drive's root directory (usually C:\). Non-privileged groups such as Users or Authenticated Users must not have greater than "Read & execute" permissions except where noted as defaults. Individual accounts must not be used to assign permissions. If permissions are not as restrictive as the default permissions listed below, this is a finding. Viewing in File Explorer: View the Properties of the system drive's root directory. Select the "Security" tab, and the "Advanced" button. Default permissions: C:\ Type - "Allow" for all Inherited from - "None" for all Principal - Access - Applies to SYSTEM - Full control - This folder, subfolders, and files Administrators - Full control - This folder, subfolders, and files Users - Read & execute - This folder, subfolders, and files Users - Create folders/append data - This folder and subfolders Users - Create files/write data - Subfolders only CREATOR OWNER - Full Control - Subfolders and files only Alternately, use icacls: Open "Command Prompt (Admin)". Enter "icacls" followed by the directory: "icacls c:\" The following results should be displayed: c:\ NT AUTHORITY\SYSTEM:(OI)(CI)(F) BUILTIN\Administrators:(OI)(CI)(F) BUILTIN\Users:(OI)(CI)(RX) BUILTIN\Users:(CI)(AD) BUILTIN\Users:(CI)(IO)(WD) CREATOR OWNER:(OI)(CI)(IO)(F) Successfully processed 1 files; Failed processing 0 files

Fix Text

Maintain the default permissions for the system drive's root directory and configure the Security Option "Network access: Let Everyone permissions apply to anonymous users" to "Disabled" (WN19-SO-000240). Default Permissions C:\ Type - "Allow" for all Inherited from - "None" for all Principal - Access - Applies to SYSTEM - Full control - This folder, subfolders, and files Administrators - Full control - This folder, subfolders, and files Users - Read & execute - This folder, subfolders, and files Users - Create folders/append data - This folder and subfolders Users - Create files/write data - Subfolders only CREATOR OWNER - Full Control - Subfolders and files only

Additional Identifiers

Rule ID: SV-205734r958702_rule

Vulnerability ID: V-205734

Group Title: SRG-OS-000312-GPOS-00122

Expert Comments

CCIs tied to check.

Controls tied to check. These are derived from the CCIs shown above.