3.2 Sessions are invalidated on user log out

Verify that sessions are invalidated when the user logs out.

Levels: 1, 2, 3

Drupal 7

Drupal does this by default for /user/logout, but be wary of custom frontend logins!

General

If a session can still be used after logging out then the lifetime of the session is increased and that gives third parties that may have intercepted the session token more (or perhaps infinite, if no absolute session expiry happens) time to impersonate a user.

One quick way to test this is to log in, get the session token from the cookie, log out, then manually add the session cookie with the session token and see if you are still logged in.

PHP

Look for session_destroy in the logout functionality.

Symfony 2

This is a setting in security.yml:

used by the default session controls.