For example, a credential in the form of a web cookie might have a field that indicates the access rights of a user. By manually tweaking this cookie, a user might be able to increase their access rights to the server. Alternately an attacker may be able to manipulate an existing credential to appear as a different user. This attack differs from falsification through prediction in that the user bases their modified credentials off existing credentials instead of using patterns detected in prior credentials to create a new credential that is accepted because it fits the pattern. As a result, an attacker may be able to impersonate other users or elevate their permissions to a targeted service.