On 02/11/2014 12:28 PM, Michal Zalewski wrote:
I believe I have a legitimate use-case (described in comment #9) for needing
to change the URL in "beforeunload".
I am probably at least partly to blame for the browsers not letting
you do that - I reported several onbeforeunload attacks some 8 years
In general, there is a security-driven desire to prevent a website
from "trapping" visitors and not allowing them to navigate away. This
not just a matter of nuisance attacks, but when employed in a clever
way, can be a powerful tool for phishing if you can convince the user
to type in a known URL and then spoof the page transition.
If we end up allowing navigation to be aborted or modified from within
unload-related events, we need to keep that in mind.
I had a feeling this was security related :)
Correct me if I'm wrong, but don't the attacks you mentioned rely upon
access to history.back()/forward()? Would it be safe to allow
history.replaceState() while forbidding the other two? Meaning, we would
allow a page to rewrite its own address but not other pages' addresses.