This is a revision of a previous post I did. In this version there are fewer steps that need to be performed in the policy. The key here is Item Level targeting, it allows you to apply policies to specific targets in your Active Directory. In this case the target would be a specific computer.
Open up your group policy managment console. Via the run command if you’re on the server, gpmc.msc. I run my policy manager from a Win 7 desktop on the domain, for this you need to install and setup the Remote Server Administration Tools, and run them with Domain Admin credentials. Once you have this open navigate down through your forest and domain to the right organizational unit (ou) where your new admin policy will sit. Generally you want to apply this in the computer OU, as the policy will be affecting desktops on your domain.
Right click on the OU and select “Create a GPO in this domain, and Link it here…“. Give the new Group Policy Object a new name and click OK. Now right click the new GPO and select “Edit…“, this will bring up the GPO editor.
Since this policy applies to a specific computer we will select the Computer Configuration, Preferences, Control Panel Settings, and Local Users and Groups. On the right pane of this option right click and select New, Local Group. In the properties of this for Action: select Update. Group name: will be Administrators (built-in), this is the local Administrators group on all PCs. Rename to: renames the Administrators group on the target PC. Description: is just a description you might want to put in here “Administrators for computer X”. Next click Add under the Members: pane. This will bring up the Local Group Member prompt. In the Name: field type in %DomainName%\userid , where the userid is a specific logon ID and in my case tuser or my domain Test User account. %DomainName% is a variable and in this case it is the domain that the GPO resides in. If you want to see all the available variables hit F3 in the Name: field.
Click OK on the Local Group Member prompt.
Now click the Common tab in the New Local Group Properties window. Here is where we target which computer that this policy will be applied to. On the Common tab check off Item-level targeting and click the Targeting… button.
In the target editor on the top left select New Item and Computer Name. the NetBIOS computer name is should appear. In the pane below click the “…” button, here is where you select the computer this policy will apply to. Type in a computer name and click Check Names, it should underline the computer name if found correctly.
Click OK, OK, and OK. Congratulations you have successfully assigned a user to the local administrator group on a single computer on the domain.
You can also rename this to reflect more closely what the Action does. Highlight it and press F2, then rename.
Go ahead, close the Group Policy Management Editor, you’re done.
NOTE: If you want to add a single user on the network as an Administrator on all the network computers your best bet for Item Level targeting is to create a Security Group and make all Domain computers members of this group. One you’ve done that use Item Level targeting and target this said group.