Membership to the Schema Admins group must be limited.

Severity	Group ID	Group Title	Version	Rule ID	Date	STIG Version
medium	V-243502	SRG-OS-000480	AD.0017	SV-243502r1026198_rule	2024-09-13	3

Description
The Schema Admins group is a privileged group in a forest root domain. Members of the Schema Admins group can make changes to the schema, which is the framework for the Active Directory forest. Changes to the schema are not frequently required. This group only contains the Built-in Administrator account by default. Additional accounts must only be added when changes to the schema are necessary and then must be removed.

Description

The Schema Admins group is a privileged group in a forest root domain. Members of the Schema Admins group can make changes to the schema, which is the framework for the Active Directory forest. Changes to the schema are not frequently required. This group only contains the Built-in Administrator account by default. Additional accounts must only be added when changes to the schema are necessary and then must be removed.

ℹ️ Check
Open "Active Directory Users and Computers" on a domain controller in the forest root domain. Navigate to the "Users" container. Right-click on "Schema Admins" and select "Properties", and then select the "Members" tab. If any accounts other than the built-in Administrators group are members, verify their necessity with the ISSO. If any accounts are members of the group when schema changes are not being made, this is a finding.

ℹ️ Check

Open "Active Directory Users and Computers" on a domain controller in the forest root domain. Navigate to the "Users" container. Right-click on "Schema Admins" and select "Properties", and then select the "Members" tab. If any accounts other than the built-in Administrators group are members, verify their necessity with the ISSO. If any accounts are members of the group when schema changes are not being made, this is a finding.

✔️ Fix
Limit membership in the Schema Admins group to only those accounts necessary during a schema update. Remove accounts when the updates are complete. Document accounts necessary during schema updates with the ISSO.