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Date:      Tue, 29 Apr 2008 09:18:45 -0500 (CDT)
From:      Bob Friesenhahn <bfriesen@simple.dallas.tx.us>
To:        Mikhail Teterin <mi+kde@aldan.algebra.com>
Cc:        cvs-ports@freebsd.org, cvs-all@freebsd.org, Henrik Brix Andersen <brix@freebsd.org>, ports-committers@freebsd.org
Subject:   Re: cvs commit: ports/graphics/GraphicsMagick Makefile distinfo
Message-ID:  <Pine.SOC.4.64.0804290908040.953@freddy.simplesystems.org>
In-Reply-To: <200804290822.29305@aldan>
References:  <200804290052.m3T0q6bB088900@repoman.freebsd.org> <20080429055949.GA1517@tirith.brixandersen.dk> <200804290822.29305@aldan>

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On Tue, 29 Apr 2008, Mikhail Teterin wrote:

> On ???????? 29 ??????? 2008, Henrik Brix Andersen wrote:
> =3D > =A0 Update to 1.1.12, which (partially) fixes some potential securi=
ty
> =3D > =A0 flaws...
> =3D
> =3D The flaws are only partially fixed? Or the update is only partially a
> =3D security update?
>
> My understanding -- from the author's description (CC-ed) -- is that the =
flaws
> are inherent and can not be /fully/ fixed. ImageMagick and GraphicsMagick
> both look at the filename for the "special characters" and extensions. By
> carefully crafting those, it may be possible to cause them to launch othe=
r
> executables...

Yes, this is the case.  The likely file format is derived from the=20
file name, which may be over-ridden by an explicit format specifier=20
prefix (e.g. "TIFF:foo") or a test of the header of the existing file.

For the extension "X", the request is passed to some X11 support code=20
which either imports an image from the screen, or displays the image=20
to the screen.

For extensions matching a "delegate" entry in the delegates.mgk XML=20
file, the matching delegate entry is executed (executing an external=20
program) with the whole filename as its input or output depending on=20
usage context.  External program execution is believed to be secure in=20
GraphicsMagick but execution of those external programs may be very=20
much unwanted in a server context.

This is the summary I wrote for the annoncement text:

  "GraphicsMagick 1.1.12 is now released.  This release helps diminish=20
the risk of external delegate exploits, and X11 exploits, via=20
carefully-crafted file names.  For example, prior to this release, an=20
X11 screen capture could be triggered, a web browser could be started,=20
a job could be sent to the printer, and The GIMP could be started, due=20
to requesting the read or write of ordinary-looking file names with=20
particular extensions.  This issue is not new and in fact has existed=20
in ImageMagick since the '90s."

Bob
=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=
=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D
Bob Friesenhahn
bfriesen@simple.dallas.tx.us, http://www.simplesystems.org/users/bfriesen/
GraphicsMagick Maintainer,    http://www.GraphicsMagick.org/
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