W3C home > Mailing lists > Public > www-font@w3.org > April to June 2011

Re: css3-fonts: should not dictate usage policy with respect to origin

From: Thomas Phinney <tphinney@cal.berkeley.edu>
Date: Thu, 30 Jun 2011 14:37:03 -0700
Message-ID: <BANLkTik6pdsP7CGzka_gfrMukAbgo0tU5Q@mail.gmail.com>
To: Glenn Adams <glenn@skynav.com>
Cc: John Daggett <jdaggett@mozilla.com>, John Hudson <tiro@tiro.com>, Vladimir Levantovsky <Vladimir.Levantovsky@monotypeimaging.com>, liam@w3.org, StyleBeyondthePunchedCard <www-style@w3.org>, public-webfonts-wg@w3.org, www-font@w3.org, "Martin J." <duerst@it.aoyama.ac.jp>, Sylvain Galineau <sylvaing@microsoft.com>
On Thu, Jun 30, 2011 at 9:09 AM, Glenn Adams <glenn@skynav.com> wrote:

> There is no mechanism to allow script content to access font data, even by
> inference (as was used in the image theft example you cite). Further, unlike
> JS or OpenGL Shader code, fonts do not employ a user defined, turing
> complete language. I admit it can be effectively argued that TTF 'mort' and
> 'morx' tables define FSMs, and that a malicious font could be constructed
> that would put the FSM into a loop, thus potentially creating a DoS risk.
> Actually, the same applies to OTF 'gsub' and 'gpos', which, due to the
> chaining mechanism, could also be exploited to create a circular chaining
> loop.
>
> However, these risks are present independently of origin processing. Other
> than these risks, the only use I can see for same origin in regards to fonts
> is the protection of font owner IPR, which is clearly in the domain of
> content protection (CP).
>
> I may be missing something here, but I have seen it said here that SO on
> fonts helps protect end users. But all I see is very weak CP for font
> owners. Please explain the security risk for CO fonts on end users.
>

>From the font side of the fence, over the years I have seen what most folks
would consider a surprising number of things arise in terms of security
issues around fonts, of a wide range of types, from multiple kinds of DOS
attacks to enabling fraud. The potential for fonts to cause problems is
often understated. Some of these issues have not been widely publicized, but
rather quietly fixed or worked around by the vendors in question.

Cheers,

T
Received on Thursday, 30 June 2011 21:37:48 GMT

This archive was generated by hypermail 2.2.0+W3C-0.50 : Thursday, 30 June 2011 21:37:48 GMT