> My first thought was if someone manages to grab the session ID he/she
> can logout the valid user immediately by trying to access the web
> application with this session ID.
>
> But after rethinking maybe the original poster thought about a second
> login with a *valid* authentication. This would not be vulnerable to DoS
> attack. Well, still I'd assume it's bad advice to close all sessions. A
> better approach would be to refuse the second login.
Refusing the second login would cause the dos attack. If I hijack your
session and have a bot "sit on it" you will never beable to log in again.
By closing any secondary sessions on a valid login you provide a way for
a user to stop an inprogress hijacking. The only problems with this
occur if you expect multiple logins at once, or the users creds are
stolen (which is a problem larger then session hijacking and dos issues).
dd
Received on Apr 01 2004
Intro
