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Re: [webappsec] POLL: Getting CSP 1.1 to LCWD

From: Daniel Veditz <dveditz@mozilla.com>
Date: Tue, 01 Oct 2013 14:51:59 -0700
Message-ID: <524B43FF.2020104@mozilla.com>
To: Glenn Adams <glenn@skynav.com>
CC: Brad Hill <hillbrad@gmail.com>, "public-webappsec@w3.org" <public-webappsec@w3.org>
On 10/1/2013 1:46 PM, Glenn Adams wrote:
> "Privilege escalation vulnerabilities are common in Firefox, and
> comprise roughly a third of the critical vulnerability advisories. [...]"
> 
> I can't comment on the age of this report or whether the same concerns
> remain active, but it is sufficient to cause me to be concerned about
> this as an attack vector.

That seems to be a concern about Firefox, not add-ons.

> In my commenting here, I am representing Cox, who, as a commercial video
> service provider, is required to meet regulatory requirements about
> presenting Emergency Alert Messages to end users while they are actively
> using this service. Failure to do everything reasonably possible to
> present an Emergency Alert could have liability consequences.

The internet in general and the World Wide Web in particular are not a
video service. How does this requirement apply in any way?

> It seems reasonable on our reading of CSP that it do a better job of
> reducing exposure to attacks from compromised add-on script injection,

I'd worry far more about malicious addons than compromised ones. The
former is a reality, but CSP isn't going to help that problem.

> Again, I'm attempting to find a better balance than that suggested by
> current CSP specification text, which states "a CSP policy /should
> not/ interfere with the operation of user-supplied scripts such as
> third-party user-agent add-ons". I believe this is too open-ended and
> that reasonable technical options exist to better protect both end user
> and content author.

My eventual plan for Firefox is to let an add-on specify a CSP
whitelist. This lets the add-ons do what the user presumably want them
to do but by default means add-ons will respect CSP. The explicit steps
to override CSP can then be reviewed and won't accidentally introduce
issues. Although perhaps not as wide open as the spec implies I think
that fits with the spirit of the spec ("should not", not "must not").

-Dan Veditz



Received on Tuesday, 1 October 2013 21:52:33 UTC

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