|Platform: win10||Date: (C)2016-09-23 (M)2018-07-10|
Impersonate a client after authentication
The policy setting allows programs that run on behalf of a user to impersonate that user (or another specified account) so that they can act on behalf of the user. If this user right is required for this kind of impersonation, an unauthorized user will not be able to convince a client to connect-for example, by remote procedure call (RPC) or named pipes-to a service that they have created to impersonate that client, which could elevate the unauthorized user's permissions to administrative or system levels.
Services that are started by the Service Control Manager have the built-in Service group added by default to their access tokens. COM servers that are started by the COM infrastructure and configured to run under a specific account also have the Service group added to their access tokens. As a result, these processes are assigned this user right when they are started.
Also, a user can impersonate an access token if any of the following conditions exist:
- The access token that is being impersonated is for this user.
- The user, in this logon session, logged on to the network with explicit credentials to create the access token.
- The requested level is less than Impersonate, such as Anonymous or Identify.
An attacker with the Impersonate a client after authentication user right could create a service, trick a client to make them connect to the service, and then impersonate that client to elevate the attacker's level of access to that of the client.
When configuring a user right in the SCM enter a comma delimited list of accounts. Accounts can be either local or located in Active Directory, they can be groups, users, or computers.
On member servers, ensure that only the Administrators and Service groups have the Impersonate a client after authentication user right assigned to them. Computers that run IIS 6.0 must have this user right assigned to the IIS_WPG group (which grants it to the Network Service account).
In most cases this configuration will have no impact. If you have installed optional components such as ASP.NET or IIS, you may need to assign the Impersonate a client after authentication user right to additional accounts that are required by those components, such as IUSR_, IIS_WPG, ASP.NET or IWAM_.
(1) GPO: Computer Configuration\Windows Settings\Security Settings\Local Policies\User Rights Assignment\Impersonate a client after authentication
(2) REG: ###
(3) WMI: root\rsop\computer
UserRight='SeImpersonatePrivilege' and precedence=1
|SCAP Repo OVAL Definition||oval:org.secpod.oval:def:36527|