Question

Hi I have recently read JSP and came across its technologies, mainly session. Under session, I read URL rewriting one of the method that was been done in order to maintain the session with the client. But since the URL rewriting changes the URL with the session ID and it can be visible to the client.
Is that not a security issue? Lets say for example, if any one note this session ID apart from the particular user, and can make a bad use of it? Or else there are techniques for preventing these?

Correct me if am wrong.

Answer 1

Certainly this is a security concern. If you quickly take note of the jsessionid value, either from a by someone else mistakenly in public copypasted URL or a in public posted screenshot of some HTTP debugging tool (Firebug) which shows the request/response headers, and the website in question maintains users by a login, then you’ll be able to login under the same user by just appending the jsessionid cookie to the URL or the request headers. Quickly, because those sessions expire by default after 30 minutes of inactivity. This is called a session fixation attack.

You can disable URL rewriting altogether so that the jsessionid never appears in the URL. But you’re still sensitive to session fixation attacks, some hacker might have installed a HTTP traffic sniffer in a public network or by some trojan/virus, or even used XSS to learn about those cookies. To be clear, this security issue is not specific to JSP, a PHP, ASP or whatever website which maintains the login by a cookiebased session, is as good sensitive to this.

To be really safe with regard to logins, let the login and logged-in traffic go over HTTPS instead of HTTP and make the cookie HTTPS (secure) only.