[webkit-dev] Timing attacks on CSS Shaders (was Re:Security problems with CSS shaders)
abarth at webkit.org
Wed Dec 7 19:29:24 PST 2011
On Wed, Dec 7, 2011 at 7:23 PM, Vincent Hardy <vhardy at adobe.com> wrote:
>>> So I take back my statement that CSS Shaders are less dangerous than
>>> WebGL. They are more!!!
> It seems to me that the differences are:
> a. It is easier to do the timing portion of a timing attack in WebGL because
> it all happens in a script and the timing is precise. With CSS shaders, the
> timing is pretty coarse.
> b. The content that a CSS shader has access to may be more sensitive than
> the content a WebGL shader has access to because currently, WebGL cannot
> render HTML (but isn't it possible to render an SVG with a foreignObject
> containing HTML into a 2D canvas, and then use that as a texture? In that
> case, wouldn't the risk be the same? Or is the canvas tainted in that case
> and cannot be used as a texture?).
Bear in mind that these security problems have been addressed in
WebGL. WebGL no long suffers from these vulnerabilities.
>>> Can this proposal be moved forward on CORS +
>>> HTMLMediaElement, HTMLImageElement and HTMLCanvasElement?
> At the last FX meeting, I got an action to sync. up with the CORS group and
> discuss how CORS would apply to CSS shaders.
It's very unclear to me how CORS can help in this situation. Can you
explain what you have in mind?
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