What does `<script>` do, in a url?

Question

In this document, page 7, it describes a vulnerability that may happen when a user is tricked into going to "http://online.worldbank.dom/<script>document.cookie="sessionid=1234;domain=.worldbank.dom”;</script>.idc". (They also include a url with <meta> at the end, as an example.) I noticed that at least in Firefox, this only gives 404 error. For example, http://example.iana.org/%3Cscript%3Ealert%28%27hi%27%29;%3C/script%3E.htm

I know there's javascript: "url" prefix, but was there also a bug in old browsers that somehow allowed scripts in the url? Or is this document implying something completely different?

One other thing I don't quite understand - on page 11:

"Notes: It’s important to realize that using an encrypted communication between the user’s browser and the target web server has literally no effect on the exploitability of session fixation vulnerabilities."

It says this in the section that describes network sniffing and injecting, is that really possible with https??

Answer 1

The idea with session fixation is that the attacker doesn't need to pay attention to whether or not it's https. Sniffing is not needed.

Normally the attacker could try to steal a valid session id by sniffing, and then take over the user's session. With session fixation the attacker picks a session id, and then tricks the victims browser into using that preselected session id. Thus there is no need to sniff. The session id is already known.

Regarding script-tags in the url, that attack will work in some, but not all websites. If the website has (as described) a cross site scripting (XSS) then the attacker can craft a url with a fixation attack. However a more likely scenario is injecting scripts that steal the current session id, but this may not work if the session cookie is httpOnly. In this case session fixation might be a better option for the attacker.