Allen,

You are correct about the security attribute being able to disable
frame busting scripts in IE. IE8 supports a X-Frame-Options HTTP
response header which can be used by a developer to deny their
approval page from rendering in a frame. However IE8 is not currently
widely used. Even requiring that javascript be enabled is not a
perfect solution. In my conversation with Google's security team they
informed me that they were going to add frame busting javascript
(which they have done) and possibly add the X-Frame-Options header. I
think that this is the best a service provider can hope to do at this
point. There really is no 100% solution.

Stephen Sclafani

On May 4, 4:15 pm, Allen Tom <[email protected]> wrote:
> Hi Stephen,
>
> Thanks for pointing this out. It might not be sufficient to deploy only
> Framebusting JS on the approval screens, as the attacker can disable JS
> for the iframe in IE by setting the security attribute to "restricted"
>
> http://msdn.microsoft.com/en-us/library/ms534622(VS.85).aspx
>
> SPs may need to deploy Framebusting JS AND require that JS is enabled
> for users to approve the Access Token, otherwise the attacker could
> embed the approval screen in an iframe with JS disabled.
>
> Allen
>
> Stephen Sclafani wrote:
> > There has been much discussion over the session fixation vulnerability
> > since it was announced publicly. There is another issue that is not
> > unique to OAuth but one that I believe poses an equal if not more
> > serious threat to service providers. That issue is clickjacking.
>
> > For those unfamiliar with clickjacking, it is when a visitor to a web
> > page is tricked into clicking on an element that they believe to be
> > harmless when in reality they are clicking on an element on a
> > different website that exposes protected data or grants an attacker
> > access. A malicious consumer developer can use a clickjacking attack
> > against a vulnerable service provider's approval page to trick users
> > into granting their application access.
>
> > Current service providers have been notified. Google, Yahoo and
> > Twitter have already deployed protection. I have written a blog post
> > that goes into greater detail on the threat which can be read here:
>
> >http://stephensclafani.com/2009/05/04/clickjacking-oauth/
>
> > Stephen Sclafani
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