An extensible token framework is provided for identifying purpose and behavior of run time security objects. The framework includes a set of marker token interfaces, which extends from a default token interface. A service provider may implement one or more marker token interfaces for a Subject or a thread of execution. A service provider may also implement its own custom marker tokens to perform custom operations. The security infrastructure runtime recognizes behavior and purpose of run time security objects based on the marker or custom marker token interfaces the token implements and handles the security objects accordingly.