Maximum lifetime for user ticket
Applies To: Windows Server 2008, Windows Server 2008 R2
This security policy reference topic for the IT professional describes the best practices, location, values, and security considerations for this policy setting.
Reference
The Maximum lifetime for user ticket policy setting determines the maximum amount of time (in hours) that a user’s ticket-granting ticket can be used. When a user’s ticket-granting ticket expires, a new one must be requested or the existing one must be renewed.
The possible values for this Group Policy setting are:
A user-defined number of hours from 0 through 99,999
Not defined
If the value for this policy setting is too high, users might be able to access network resources outside of their logon hours, or users whose accounts have been disabled might be able to continue to access network services by using valid service tickets that were issued before their account was disabled. If the value is set to 0, ticket-granting tickets never expire.
Best practices
- It is advisable to set Maximum lifetime for user ticket to 10 hours.
Location
GPO_name\Computer Configuration\Windows Settings\Security Settings\Account Policies\Kerberos Policy\
Default Values
| Server Type or GPO | Default Value |
|---|---|
Default Domain Policy |
10 hours |
Default Domain Controller Policy |
Not defined |
Stand-Alone Server Default Settings |
Not applicable |
DC Effective Default Settings |
10 hours |
Member Server Effective Default Settings |
Not applicable |
Client Computer Effective Default Settings |
Not applicable |
Operating system version differences
There are no differences in this policy for Windows versions beginning with Windows Server 2003.
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
If you configure the value for the Maximum lifetime for user ticket setting too high, users might be able to access network resources outside of their logon hours. Also, users whose accounts were disabled might continue to have access to network services with valid user tickets that were issued before their accounts were disabled. If you configure this value too low, ticket requests to the KDC may affect the performance of your KDC and present an opportunity for a DoS attack.
Countermeasure
Configure the Maximum lifetime for user ticket setting with a value between 4 and 10 hours.
Potential impact
Reducing this setting from the default value reduces the likelihood that the ticket-granting ticket will be used to access resources that the user does not have rights to. However, it requires more frequent requests to the KDC for ticket-granting tickets on behalf of users. Most KDCs can support a value of four hours without too much additional burden.