Igor Faynberg wrote:
Mike,
You've got the problem statement right: allowing the user to authorize
resource access to another party without divulging user's credentials is
the objective of OAuth. You are also right in that the attack you have
described defies the whole purpose of OAuth. I do not think though that
it is related to OAuth per se.
To this end, the security work led by Torsten has thoroughly analyzed
the protocol and specified protection against multiple protocol
attacks. From what you described, it appears to me that the attack you
mention is not related to the protocol but rather to the user's
environment. There is no possible protection from key loggers that a
protocol can implement. I could be mistaken; in any case, it looks like
the problem rests with the implementation of WebView.
There is no problem with the webview; it's working completely as intended.
An embedded webview is not a fortress for the sake of the user/server, it's
a UI element that can be manipulated by an app. And even if Android, say,
did try to make keyboard logging impossible, I could always create my own
webview UA that allowed me to log keystrokes after it rendered the server's
login page.
So it appears that there is an implicit expectation that the UA is "trusted".
Well, here's a case where that's not the case. Can the server tell the
difference?
Mike
If I am wrong, I would appreciate a detailed description of what happened.
Igor
On 9/6/2011 1:40 PM, Michael Thomas wrote:
Hi all,
Barry suggested that I might subscribe and explain what I sent him.
My basic problem is that in neither the protocol nor the threats drafts,
I can't seem to find what problem is actually trying to be solved with
oauth, and what assumptions you're making about various elements.
Here's what I did. I've written an app, and I wanted re-integrate the
ability to send tweets after they deprecated Basic. So the app has a
webView (android, iphone...) which it obviously completely controls.
With oauth, the webview UA will ultimately redirect off to Twitter's
site to collect the user's credentials and grant my app's backend an
access token (sorry if I get terminology screwed up, i'm just coming
up to speed).
What occurs to me is that webview affords exactly zero protection from
my client (ie, the app) from getting the user's twitter credentials. All
I have to do is set up a keypress handler on that webview and in a few
minutes of hacking I have a key logger. etc.
So what I can't tell is whether this is a "problem" or not, because I
don't know what problem you're trying to solve. If the object of oauth
isn't to keep user/server credentials out of the hands of a third party,
then what is it trying to solve? Is there an expectation that the
UA is trusted by the user/server? What happens when that's not the case?
Regardless of whether I'm misunderstanding, it would sure be nice to have
both the problem and your assumptions laid out, hopefully with some
prominence
so you don't get these sort of dumb questions.
Mike
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