ACLs for system files and directories must conform to minimum requirements.

Overview

Finding ID	Version	Rule ID	IA Controls	Severity
WN08-GE-000010	WN08-GE-000010	WN08-GE-000010_rule		Medium

Description
Changing the system's file and directory permissions allows the possibility of unauthorized and anonymous modification to the operating system and installed applications.

STIG	Date
Windows 8 Security Technical Implementation Guide	2012-11-21

Details

Check Text ( C-WN08-GE-000010_chk )
The default ACL settings are adequate when the Security Option "Network access: Let everyone permissions apply to anonymous users" is set to "Disabled" (V-3377) and Power User Group Membership is restricted. If the default ACLs are maintained, the referenced option is set to "Disabled", and Powers Users are restricted, this is not a finding. Verify the default permissions for the sample directories below. 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.) Viewing in File Explorer, Select the "Security" tab, and the "Advanced" button. C:\ Type - "Allow" for all Inherited from - "None" for all Principal - Access - Applies to Administrators - Full control - This folder, subfolders and files SYSTEM - Full control - This folder, subfolders and files Users - Read & execute - This folder, subfolders and files Authenticated Users - Modify - Subfolders and files only Authenticated Users - Create folders / append data - This folder only \Program Files Type - "Allow" for all Inherited from - "None" for all Principal - Access - Applies to TrustedInstaller - Full control - This folder and subfolders SYSTEM - Modify - This folder only SYSTEM - Full control - Subfolders and files only Administrators - Modify - This folder only Administrators - Full control - Subfolders and files only Users - Read & execute - This folder, subfolders and files CREATOR OWNER - Full control - Subfolders and files only ALL APPLICATION PACKAGES - Read & execute - This folder, subfolders and files \Windows Type - "Allow" for all Inherited from - "None" for all Principal Access Applies to TrustedInstaller - Full control - This folder and subfolders SYSTEM - Modify - This folder only SYSTEM - Full control - Subfolders and files only Administrators - Modify - This folder only Administrators - Full control - Subfolders and files only Users - Read & execute - This folder, subfolders and files CREATOR OWNER - Full control - Subfolders and files only ALL APPLICATION PACKAGES - Read & execute - This folder, subfolders and files Alternately use Icacls. In a Command prompt (admin) Enter icacls followed by the directory. icacls c:\ icacls "c:\program files" icacls c:\windows The following results will be displayed as each is entered: c:\ BUILTIN\Administrators:(OI)(CI)(F) NT AUTHORITY\SYSTEM:(OI)(CI)(F) BUILTIN\Users:(OI)(CI)(RX) NT AUTHORITY\Authenticated Users:(OI)(CI)(IO)(M) NT AUTHORITY\Authenticated Users:(AD) Mandatory Label\High Mandatory Level:(OI)(NP)(IO)(NW) Successfully processed 1 files; Failed processing 0 files c:\program files NT SERVICE\TrustedInstaller:(F) NT SERVICE\TrustedInstaller:(CI)(IO)(F) NT AUTHORITY\SYSTEM:(M) NT AUTHORITY\SYSTEM:(OI)(CI)(IO)(F) BUILTIN\Administrators:(M) BUILTIN\Administrators:(OI)(CI)(IO)(F) BUILTIN\Users:(RX) BUILTIN\Users:(OI)(CI)(IO)(GR,GE) CREATOR OWNER:(OI)(CI)(IO)(F) APPLICATION PACKAGE AUTHORITY\ALL APPLICATION PACKAGES:(RX) APPLICATION PACKAGE AUTHORITY\ALL APPLICATION PACKAGES:(OI)(CI)(IO)(GR,GE) Successfully processed 1 files; Failed processing 0 files c:\windows NT SERVICE\TrustedInstaller:(F) NT SERVICE\TrustedInstaller:(CI)(IO)(F) NT AUTHORITY\SYSTEM:(M) NT AUTHORITY\SYSTEM:(OI)(CI)(IO)(F) BUILTIN\Administrators:(M) BUILTIN\Administrators:(OI)(CI)(IO)(F) BUILTIN\Users:(RX) BUILTIN\Users:(OI)(CI)(IO)(GR,GE) CREATOR OWNER:(OI)(CI)(IO)(F) APPLICATION PACKAGE AUTHORITY\ALL APPLICATION PACKAGES:(RX) APPLICATION PACKAGE AUTHORITY\ALL APPLICATION PACKAGES:(OI)(CI)(IO)(GR,GE) Successfully processed 1 files; Failed processing 0 files Note: Power Users is included in later Windows versions for backward compatibility. If an ACL setting prevents a site's applications from performing properly, settings must only be changed to the minimum necessary for the application to function. Each exception must be documented with the IAO.

Check Text ( C-WN08-GE-000010_chk )

The default ACL settings are adequate when the Security Option "Network access: Let everyone permissions apply to anonymous users" is set to "Disabled" (V-3377) and Power User Group Membership is restricted. If the default ACLs are maintained, the referenced option is set to "Disabled", and Powers Users are restricted, this is not a finding.

Verify the default permissions for the sample directories below. 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.)

Viewing in File Explorer,
Select the "Security" tab, and the "Advanced" button.

C:\
Type - "Allow" for all
Inherited from - "None" for all
Principal - Access - Applies to
Administrators - Full control - This folder, subfolders and files
SYSTEM - Full control - This folder, subfolders and files
Users - Read & execute - This folder, subfolders and files
Authenticated Users - Modify - Subfolders and files only
Authenticated Users - Create folders / append data - This folder only

\Program Files
Type - "Allow" for all
Inherited from - "None" for all
Principal - Access - Applies to
TrustedInstaller - Full control - This folder and subfolders
SYSTEM - Modify - This folder only
SYSTEM - Full control - Subfolders and files only
Administrators - Modify - This folder only
Administrators - Full control - Subfolders and files only
Users - Read & execute - This folder, subfolders and files
CREATOR OWNER - Full control - Subfolders and files only
ALL APPLICATION PACKAGES - Read & execute - This folder, subfolders and files

\Windows
Type - "Allow" for all
Inherited from - "None" for all
Principal Access Applies to
TrustedInstaller - Full control - This folder and subfolders
SYSTEM - Modify - This folder only
SYSTEM - Full control - Subfolders and files only
Administrators - Modify - This folder only
Administrators - Full control - Subfolders and files only
Users - Read & execute - This folder, subfolders and files
CREATOR OWNER - Full control - Subfolders and files only
ALL APPLICATION PACKAGES - Read & execute - This folder, subfolders and files

Alternately use Icacls.

In a Command prompt (admin)
Enter icacls followed by the directory.

icacls c:\
icacls "c:\program files"
icacls c:\windows

The following results will be displayed as each is entered:

c:\
BUILTIN\Administrators:(OI)(CI)(F)
NT AUTHORITY\SYSTEM:(OI)(CI)(F)
BUILTIN\Users:(OI)(CI)(RX)
NT AUTHORITY\Authenticated Users:(OI)(CI)(IO)(M)
NT AUTHORITY\Authenticated Users:(AD)
Mandatory Label\High Mandatory Level:(OI)(NP)(IO)(NW)
Successfully processed 1 files; Failed processing 0 files

c:\program files
NT SERVICE\TrustedInstaller:(F)
NT SERVICE\TrustedInstaller:(CI)(IO)(F)
NT AUTHORITY\SYSTEM:(M)
NT AUTHORITY\SYSTEM:(OI)(CI)(IO)(F)
BUILTIN\Administrators:(M)
BUILTIN\Administrators:(OI)(CI)(IO)(F)
BUILTIN\Users:(RX)
BUILTIN\Users:(OI)(CI)(IO)(GR,GE)
CREATOR OWNER:(OI)(CI)(IO)(F)
APPLICATION PACKAGE AUTHORITY\ALL APPLICATION PACKAGES:(RX)
APPLICATION PACKAGE AUTHORITY\ALL APPLICATION PACKAGES:(OI)(CI)(IO)(GR,GE)
Successfully processed 1 files; Failed processing 0 files

c:\windows
NT SERVICE\TrustedInstaller:(F)
NT SERVICE\TrustedInstaller:(CI)(IO)(F)
NT AUTHORITY\SYSTEM:(M)
NT AUTHORITY\SYSTEM:(OI)(CI)(IO)(F)
BUILTIN\Administrators:(M)
BUILTIN\Administrators:(OI)(CI)(IO)(F)
BUILTIN\Users:(RX)
BUILTIN\Users:(OI)(CI)(IO)(GR,GE)
CREATOR OWNER:(OI)(CI)(IO)(F)
APPLICATION PACKAGE AUTHORITY\ALL APPLICATION PACKAGES:(RX)
APPLICATION PACKAGE AUTHORITY\ALL APPLICATION PACKAGES:(OI)(CI)(IO)(GR,GE)
Successfully processed 1 files; Failed processing 0 files

Note: Power Users is included in later Windows versions for backward compatibility.

If an ACL setting prevents a site's applications from performing properly, settings must only be changed to the minimum necessary for the application to function. Each exception must be documented with the IAO.

Fix Text (F-WN08-GE-000010_fix)
Maintain the default file ACLs, configure the Security Option: "Network access: Let everyone permissions apply to anonymous users" to "Disabled" (V-3377) and restrict the Power Users group to include no members.