Mainframe Products requiring user access authentication must provide a logoff capability for a user-initiated communication session.

If a user cannot explicitly end an application session, the session may remain open and be exploited by an attacker; this is referred to as a zombie session. Information resources to which users gain access via authentication include, for example, local workstations, databases, and password-protected websites/web-based services. However, for some types of interactive sessions including, for example, file transfer protocol (FTP) sessions, information systems typically send logoff messages as final messages prior to terminating sessions.