Thanks for your response, this is most interesting. I didn't think
there was anything special about framework.operUrl, and since we're
trying to be backwards compatible to 5.1 I think we'll continue using
the activexobject.

OK, so that's a lot to think about. Firstly you advise using a secure
connection whenever posting data; happily we're already doing this.
The gets are using non-secure connections, but (with the exception of
the download URL) all responses are verified before parsing.

Secondly all asynch responses are XML, not JSON, so no danger of eval-
ing something nasty. The download URL is the only instance where un-
audited response data is given directly to the user.

Thirdly, there's the question of the update mechanism. At the mo it
looks like this:
1. Asynch request for version info + update URL to new .gg file (not
secure)
2. Gadget displays upgrade message and "download" link
3. User clicks link, which uses WScript.Shell to run the URL in the
default browser (not secure)
4. User is prompted to save/run by the browser, following the normal
browser download flow.

If I'm understanding correctly, an attacker might intercept the asynch
version/URL request (#1), and modify the response to include a bogus
update URL. I totally agree that we should not be providing a direct
URL to the .gg file; thanks to this thread I now have external support
to convince people to provide a download *page* instead. Much better
usability if nothing else, as we can give instructions on what to do
if the install doesn't work.

Even given that change, I suppose technically our asynch XML response
would still be vulnerable to attack: someone could still modify it to
a URL of their choosing. I'm guessing we should also make this request
secure, just to be on the safe side?

Thanks for the clarification on how MITM attacks work, and that simple
links to web pages are low in risk. I think other than the two fixes
for the upgrade mechanism, it sounds like we're pretty clear. Am I
missing anything that you can tell? BTW sorry I can't send the gadget
itself; it hasn't been released yet and blah legal blah.

Elaine

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