Force GPUpdate for all computers
November 21, 2022, 10:28 pm
Hi everyone !
Today I wanted to talk about a small tip if you need to refresh a computer gpo for some computer OU.
I will talk the powershell command let; Invoke-GPUpdate
The commad let is powerfull, as you can target a computer, and to update only user settings; that way;
Invoke-GPUpdate -Computer "DOMAIN\WORKSTATION-001" -Target "User"
The last command let I wanted to talk is a more complex's one, like this one;
Get-ADComputer –filter * -Searchbase "ou=Site-A, dc=Domain,dc=com" | foreach{ Invoke-GPUpdate –computer \$_.name -force}
That one will search a complete OU for all computer account, and invoke a gpupdate /force on them.
Before running it I suggest to try the Get-ADComputer command let to be sure it target computer you want;
Get-ADComputer –filter * -Searchbase "ou=Site-A, dc=Domain,dc=com" | fl
Make sure you know that the remote user will see a gpupdate's windows, to have it hidden make sure you use -AsJob in your command let.
Thansk everyone for listening
Domain join hardening changes
November 10, 2022, 1:55 pm
Hi everyone
Today I wanted to talk a change that Microsoft did for domain join.
After the 11 October 2022 the KB5020276 introduce some concept change that will help a lot to make domain join error free.
I will quote the legacy behavior;
Before you install the October 11, 2022, or later cumulative updates, the client computer queries Active Directory for an existing account with the same name. This query occurs during domain join and computer account provisioning. If such an account exists, the client will automatically attempt to reuse it.
Note The reuse attempt will fail if the user who attempts the domain join operation does not have the appropriate write permissions. However, if the user has enough permissions the domain join will succeed.
There are two scenarios for domain join with respective default behaviors and flags as follows:
Domain Join (NetJoinDomain)
Defaults to account reuse (unless NETSETUP_NO_ACCT_REUSE flag is specified)
Account provisioning (NetProvisionComputerAccountNetCreateProvisioningPackage).
Defaults to NO reuse (unless NETSETUP_PROVISION_REUSE_ACCOUNT is specified.)
After the change there is an addional security check that is done.
- Account reuse will be permitted if done by the account creator.
- Account reuse will be permitted if done by a member of the domain admin's group.
That way if you have delegated the domain join task it enforce more security for account name.
Following that change you can see that error message; which would be normal if the two conditions are not met.
Error 0xaac (2732): NERR_AccountReuseBlockedByPolicy: “An account with the same name exists in Active Directory. Re-using the account was blocked by security policy.”
Some more information on additional's step that can be done;
Take Action
Review computer account provisioning workflows and understand if changes are required.Perform the join operation using the same account that created the computer account in the target domain.
If the existing account is stale (unused), delete it before attempting to join the domain again.
Rename the computer and join using a different account that doesn’t already exist.
If the existing account is owned by a trusted security principal and an administrator wants to reuse the account, they might do so by temporarily setting the following registry key at the individual client computer level. Then immediately remove the registry setting after the join operation is complete. No restart is necessary for changes to the registry key to take effect.
Path
HKLM\System\CurrentControlSet\Control\LSA
Type
REG_DWORD
Name
NetJoinLegacyAccountReuse
Value
1
Other values are ignored.
Important guidance for using option 4
Caution: If you choose to set this key to work around these protections, you will leave your environment vulnerable to CVE-2022-38042 unless your scenario is referenced below as appropriate. Do not use this method without confirmation that the Creator/Owner of the existing computer object is a secure and trusted security principal.It is appropriate to use solution 4 in the following scenarios:
An IT admin with delegated permissions needs to rejoin a computer to the target domain for troubleshooting purposes and the original account creator is a trusted account.
OR
A deployment scenario in which computer accounts are created before using a dedicated service account (such as SCCM or other software) and the domain join is performed by a second dedicated account with delegated domain-join permissions (for example, "This account is allowed to join this computer to the domain").
Microsoft might remove support for the NetJoinLegacyAccountReuse registry setting in a future update and replace it with an alternative method. This article will be updated if and when such changes take place.
Nonsolutions
Do not add service accounts or provisioning accounts to the Domain Admins security group.Do not manually edit the security descriptor on computer accounts in an attempt to redefine the ownership of such accounts. While editing the owner will enable the new checks to succeed, the computer account might retain the same potentially risky, unwanted permissions for the original owner unless explicitly reviewed and removed.
Do not add the NetJoinLegacyAccountReuse registry key to base OS images because the key should only be temporarily added and then removed directly after the domain join completes.
The article in reference is; KB5020276—Netjoin: Domain join hardening changes
Windows Update Error 80072F8F
November 8, 2022, 11:57 am
Hi everyone
Today I wanted to talk about a error that can happen in Windows Update.
It's the error 0x80072F8F.
That error is pointing to an error of the update client. There is two possible causes;
First: The update client is outdated, due possibly to a lack of update done over time. This tend to happen more on older OS like in Windows Server 2012 in example.
To resolve such case you can download a updated client from Microsoft;
Update to Microsoft Update client (https://support.microsoft.com/en-us/topic/update-to-microsoft-update-client-80891e31-29ed-510d-819b-a4c4ee4aa1b7)
After the update just re-run Windows Update to have it work.
Second: An error in the time set inside the computer with a huge offset will cause the update client to fail to get any information. Make sure the computer time is correct.
Wait for printer(s) Mapping on RemoteApp publication
November 2, 2022, 10:28 am
Hi ! Today I wanted to share a small tip if you need to wait for the printer mapping to map before openning a RemoteApp.
This tip is handy in case where the application doesn't refresh it's internal list of printer when it start.
Microsoft Office suite is done perfect for that matter, as you can open it, as the list of printer just update when it's ready to be used.
Some older applications (even newer) are done in more primitive's way need the printer to be there when it start.
Sage 50 is a good example, and there is some in like FoxPro language, so the tip is still valid today.
The tip is to publish a command file, .cmd or .bat that launch the application, but inside the script you can enter that before launching the app;
@echo off
ping -n 3 127.0.0.1>null
That example will add a 3 second delay before openning the application.
Account lockout available for built-in local administrators
October 31, 2022, 3:47 pm
Hi
Today I wanted to share a nice new change Microsoft introduced in the 11 October 2022 cumulative update.
Account lockout are available for built-in local administrators for any network service (RDP, etc..) but not for Console access.
If you want to see where it's;
It's a nice way to be able to block password bruteforce tip.
The location is Local Computer Policy\Computer Configuration\Windows Settings\Security Settings\Account Policies\Account Lockout Policies
To note if you use a Windows build 22H2 with the newer update to deploy computer the option will be Enabled by default, and Microsoft will enable the use of complex password at the same time. You can unset the later setting, but it can be a security risk. (Local Computer Policy\Computer Configuration\Windows Settings\Security Settings\Account Policies\Password Policy)
You can read more on the topic are; KB5020282