Why is my system failing to grant me the SeTcbPrivilege?
I'm attempting to grant a Windows interactive console process the SeTcbPrivilege privilege from a non-interactive SYSTEM process using OpenProcessToken(...) with TOKEN_ADJUST_PRIVILEGES.
Despite running as SYSTEM, the SeTcbPrivilege grant fails; as demonstrated by an audit failure in the Event Viewer when trying to perform an action with those rights and cross-checking with PrivilegeCheck(...). Granting the process SeDebugPrivilege and any other grants succeed.
My supposition is that this fails because of the 'Act as the part of the operating system' group policy, preventing even SYSTEM from granting this right to a non-SYSTEM process. Is this assumption valid, or is there some other hurdle that needs to be overcome? This is on an up-to-date, somewhat hardened, Windows 10 system.
- For each of the possible privileges on a token, there are three possible states:
- Enabled: The privilege is present on the token and is active.
- Disabled: The privilege is present on the token, but not currently active.
- Not present: The privilege was either not included when the token was created, or has been removed.
There is no way to add a privilege that the token doesn't already have. It sounds like that's what you're trying to do, though; take a token belonging to a process without SeTcbPrivilege, and add SeTcbPrivilege to it. You can't do that (not from user-mode, at least; a kernel driver presumably could). If SeTcbPrivilege is in the third state - either it wasn't there originally (because the process didn't have "Act as art of the operating system" when it was created) or it was removed by a previous call to AdjustTokenPrivileges - then what you're trying to do is impossible.
Without knowing more of what your end-goal is, I can't provide an alternative approach to the problem.
Answer (1)
The SeTcbPrivilege (Act as part of the operating system) is a powerful privilege in Windows that allows a process to assume the identity of any user and gain access to their resources. This privilege is typically required for system-level services and tasks that need to operate with elevated permissions. If you are encountering issues granting yourself the SeTcbPrivilege, it could be due to several reasons:
Common Reasons and Solutions
Insufficient Administrative Rights:
Ensure you are logged in as an administrator. Only administrators can grant or modify privileges.
If you are using an account with administrative rights but still facing issues, try running the command prompt or the relevant tool (like Local Security Policy editor) as an administrator. Right-click the program and select "Run as administrator."
Group Policy Restrictions:
Group policies set by domain administrators might restrict the assignment of SeTcbPrivilege. You might need to contact your domain administrator to modify the policy.
Local Security Policy Settings:
You can grant SeTcbPrivilege through the Local Security Policy (secpol.msc):
Open secpol.msc (Local Security Policy).
Navigate to Local Policies -> User Rights Assignment.
Find and double-click on "Act as part of the operating system".
Add the desired user or group.
Changes may require a system restart to take effect.
Script or Program Errors:
If you are using a script or program to grant the privilege, ensure it is correctly written and you are running it with administrative privileges. Here’s an example of how you might use ntrights from the Windows Resource Kit to grant the privilege:
ntrights +r SeTcbPrivilege -u YourUsernameAccount Restrictions:
Ensure the account you are trying to grant the privilege to is not restricted by any other policies. Some accounts, like guest accounts, have restricted privileges by default.
Step-by-Step Guide to Grant SeTcbPrivilege
Using Local Security Policy:
Press Win + R, type secpol.msc, and press Enter.In the Local Security Policy window, navigate to Local Policies -> User Rights Assignment.
Find and double-click "Act as part of the operating system".
Click Add User or Group and enter the user or group you want to grant the privilege to.
Click OK and Apply the changes.
Restart the computer to apply the changes.
Using Command Line:
Download the Windows Resource Kit Tools if not already installed.
Open an elevated command prompt (Run as administrator).
Use the ntrights utility to grant the privilege:
ntrights +r SeTcbPrivilege -u YourUsernameTroubleshooting
Verify Privileges: After granting the privilege, you can verify it by running whoami /priv in an elevated command prompt to see the list of privileges assigned to the current user.
Check Logs: Check the Event Viewer for any related logs that might give more insight into why the privilege assignment is failing.
Consult Documentation: Refer to the official Microsoft documentation or knowledge base for any known issues or additional steps.
By following these steps, you should be able to identify and resolve the issue preventing you from granting the SeTcbPrivilege on your system.