Replace a process level token

Applies To: Windows Vista, Windows Server 2008, Windows 7, Windows 8.1, Windows Server 2008 R2, Windows Server 2012 R2, Windows Server 2012, Windows 8

This security policy reference topic for the IT professional describes the best practices, location, values, policy management, and security considerations for this policy setting.

Reference

This policy setting determines which parent processes can replace the access token that is associated with a child process.

Specifically, the Replace a process level token setting determines which user accounts can call the CreateProcessAsUser() application programming interface (API) so that one service can start another. An example of a process that uses this user right is Task Scheduler, where the user right is extended to any processes that can be managed by Task Scheduler.

An access token is an object that describes the security context of a process or thread. The information in a token includes the identity and privileges of the user account that is associated with the process or thread. With this user right, every child process that runs on behalf of this user account would have its access token replaced with the process level token.

This policy setting is supported on versions of Windows that are designated in the Applies To list at the beginning of this topic.

Constant: SeAssignPrimaryTokenPrivilege

Possible values

• User-defined list of accounts

• Defaults

• Not defined

Best practices

1. For member servers, ensure that only the Local Service and Network Service accounts have the Replace a process level token user right.

Location

GPO_name\Computer Configuration\Windows Settings\Security Settings\Local Policies\User Rights Assignment

Default values

By default this setting is Network Service and Local Service on domain controllers and on stand-alone servers.

The following table lists the actual and effective default policy values for the most recent supported versions of Windows. Default values are also listed on the policy’s property page.

Operating system version differences

There are no differences in the way this policy setting works between the supported versions of Windows that are designated in the Applies To list at the beginning of this topic.

Policy management

This section describes features, tools, and guidance to help you manage this policy.

A restart of the computer is not required for this policy setting to be effective.

Any change to the user rights assignment for an account becomes effective the next time the owner of the account logs on.

Group Policy

Settings are applied in the following order through a Group Policy Object (GPO), which will overwrite settings on the local computer at the next Group Policy update:

1. Local policy settings

2. Site policy settings

3. Domain policy settings

4. OU policy settings

When a local setting is greyed out, it indicates that a GPO currently controls that setting.

Security considerations

This section describes how an attacker might exploit a feature or its configuration, how to implement the countermeasure, and the possible negative consequences of countermeasure implementation.

Vulnerability

Users with the Replace a process level token user right can start processes as another user if they know the user’s credentials.

Countermeasure

For member servers, ensure that only the Local Service and Network Service accounts have the Replace a process level token user right.

Potential impact

On most computers, restricting the Replace a process level token user right to the Local Service and the Network Service built-in accounts is the default configuration, and there is no negative impact. However, if you have installed optional components such as ASP.NET or IIS, you may need to assign the Replace a process level token user right to additional accounts. For example, IIS requires that the Service, Network Service, and IWAM_<ComputerName> accounts be explicitly granted this user right.

See Also

User Rights Assignment