Group Policy Object

Script to modify the defaultSecurityDescriptor attribute on the Group-Policy-Container schema class object

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Last week I published an article about the changes in the behavior of Group Policy processing after the deployment of security update MS16-072 under KB3163622. It included a script to assist with the remediation of Group Policy permissions: Script to report on and remediate the Group Policy security change in MS16-072.

Of course that’s not where it ends. What about new Group Policies? Do you create a procedure that requires you to add “Domain Computers” with Read permission every time you create a new Group Policy Object (GPO)? No…of course not!

What we need to do now is change the defaultSecurityDescriptor attribute on the Group-Policy-Container schema class object so that new GPOs are created with Domain Computers having Read permissions by default. Microsoft didn’t released an official script or method to do this, so here’s the next best thing.

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Script to report on and remediate the Group Policy security change in MS16-072

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Computer can read again!

On June 14th 2016 Microsoft released security update MS16-072 under KB3163622 that changes the behavior of Group Policy processing so that user group policies are now retrieved by using the machine’s security context instead of the user’s security context. This is a by-design behavior change from Microsoft to protect computers from a security vulnerability.

Update 23/06/2016: Microsoft finally released an official response to this patch via the Directory Services team: Deploying Group Policy Security Update MS16-072 \ KB3163622

This is a problem for people that implement security filtering on their Group Policy Objects (GPOs), as it removes the default Authenticated Users group not only from the “Apply group policy” permission, but also from the “Read” permission.

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Script to Generate a Group Policy Object (GPO) Version Report

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Is there a version match between your Group Policy Object (GPO) containers and templates?

This PowerShell script will check that the version of each GPO is consistent in the Active Directory Group Policy Container (GPC) and on each Domain Controller in the Group Policy Template (GPT).

All Windows Operating Systems (since Windows 2000) will apply the GPO regardless of a version mismatch. However, a version mismatch will typically mean that some settings will simply not be applied because they haven’t been replicated correctly across the environment. Replication issues with good old flaky FRS and perhaps (but rarely) the newer DFS-R is often the reason that the GPT gets out of sync and lags behind the GPC. This is such a common problem.

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Finding Orphaned Group Policy Objects

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Group Policy Objects (GPOs) are stored in two parts:

  1. GPC (Group Policy Container). The GPC is where the GPO stores all the AD-related configuration under the CN=Policies,CN=System,DC=… container, which is replicated via AD replication.
  2. GPT (Group Policy Templates). The GPT is where the GPO stores the actual settings located within SYSVOL area under the Policies folder, which is replicated by either File Replication Services (FRS) or Distributed File System (DFS).

This script will help find GPOs that are missing one of the parts, which therefore makes it an orphaned GPO.

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