#25993 texlive CVE-2016-10243

Message #5 received at submit@debbugs.gnu.org (full text, mbox, reply):

From: Leo Famulari <leo@famulari.name>

To: guix-patches@gnu.org

Subject: texlive CVE-2016-10243

Date: Sun, 5 Mar 2017 22:30:58 -0500

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This fixes CVE-2016-10243:

"The TeX system allows for calling external programs from within the
TeX source code (called \write18). This has been restricted to a
small set of programs since a long time ago.

Unfortunately it turned out that one program in the list, mpost
(also shipped with TeX Live), allows in turn to specify other
programs to be run, which allows arbitrary code execution when
compiling a TeX document."

source:
http://seclists.org/oss-sec/2017/q1/555

This patch prevents the POC described in blog post:

https://scumjr.github.io/2016/11/28/pwning-coworkers-thanks-to-latex/

[0001-gnu-texlive-Fix-CVE-2016-10243.patch (text/plain, attachment)]

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Message #8 received at 25993@debbugs.gnu.org (full text, mbox, reply):

From: Ricardo Wurmus <rekado@elephly.net>

To: Leo Famulari <leo@famulari.name>

Cc: 25993@debbugs.gnu.org

Subject: Re: bug#25993: texlive CVE-2016-10243

Date: Mon, 06 Mar 2017 10:02:06 +0100

Leo Famulari <leo@famulari.name> writes:

> This fixes CVE-2016-10243:

Thanks for preparing the patch to fix this.

> diff --git a/gnu/packages/patches/texlive-texmf-CVE-2016-10243.patch b/gnu/packages/patches/texlive-texmf-CVE-2016-10243.patch
> new file mode 100644
> index 000000000..3a9ae993f
> --- /dev/null
> +++ b/gnu/packages/patches/texlive-texmf-CVE-2016-10243.patch
> @@ -0,0 +1,18 @@
> +Fix CVE-2016-10243:
> +
> +https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2016-10243
> +
> +Patch adapted from upstream commit:
> +
> +https://www.tug.org/svn/texlive?view=revision&revision=42605
> +
> +--- trunk/Master/texmf-dist/web2c/texmf.cnf	2016/11/29 23:10:33	42604
> ++++ trunk/Master/texmf-dist/web2c/texmf.cnf	2016/11/29 23:27:53	42605
> +@@ -568,7 +568,6 @@ extractbb,\
> + gregorio,\
> + kpsewhich,\
> + makeindex,\
> +-mpost,\
> + repstopdf,\
> +
> + % we'd like to allow:
> diff --git a/gnu/packages/tex.scm b/gnu/packages/tex.scm

Is this sufficient?  I see here that two files need this change:

    https://www.tug.org/svn/texlive?view=revision&revision=42605

Should “trunk/Build/source/texk/kpathsea/texmf.cnf” also be patched?

--
Ricardo

GPG: BCA6 89B6 3655 3801 C3C6  2150 197A 5888 235F ACAC
https://elephly.net

Message #11 received at 25993@debbugs.gnu.org (full text, mbox, reply):

From: Leo Famulari <leo@famulari.name>

To: Ricardo Wurmus <rekado@elephly.net>

Cc: 25993@debbugs.gnu.org

Subject: Re: bug#25993: texlive CVE-2016-10243

Date: Mon, 6 Mar 2017 13:30:00 -0500

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On Mon, Mar 06, 2017 at 10:02:06AM +0100, Ricardo Wurmus wrote:
> Is this sufficient?  I see here that two files need this change:
> 
>     https://www.tug.org/svn/texlive?view=revision&revision=42605
> 
> Should “trunk/Build/source/texk/kpathsea/texmf.cnf” also be patched?

I inspected the built output of texlive, texlive-bin, and texlive-texmf,
and none of them include the texmf.cnf file for kpathsea.

That file does exist in the source.

AFAICT, the only .cnf file in our built package that whitelists mpost is
the one I patched.

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Message #14 received at 25993@debbugs.gnu.org (full text, mbox, reply):

From: Ricardo Wurmus <rekado@elephly.net>

To: Leo Famulari <leo@famulari.name>

Cc: 25993@debbugs.gnu.org

Subject: Re: bug#25993: texlive CVE-2016-10243

Date: Mon, 06 Mar 2017 22:32:04 +0100

Leo Famulari <leo@famulari.name> writes:

> On Mon, Mar 06, 2017 at 10:02:06AM +0100, Ricardo Wurmus wrote:
>> Is this sufficient?  I see here that two files need this change:
>> 
>>     https://www.tug.org/svn/texlive?view=revision&revision=42605
>> 
>> Should “trunk/Build/source/texk/kpathsea/texmf.cnf” also be patched?
>
> I inspected the built output of texlive, texlive-bin, and texlive-texmf,
> and none of them include the texmf.cnf file for kpathsea.
>
> That file does exist in the source.
>
> AFAICT, the only .cnf file in our built package that whitelists mpost is
> the one I patched.

Thank you for confirming this.  The patch looks good to me!

-- 
Ricardo

GPG: BCA6 89B6 3655 3801 C3C6  2150 197A 5888 235F ACAC
https://elephly.net

Message #17 received at 25993@debbugs.gnu.org (full text, mbox, reply):

From: Leo Famulari <leo@famulari.name>

To: Ricardo Wurmus <rekado@elephly.net>

Cc: 25993@debbugs.gnu.org

Subject: Re: bug#25993: texlive CVE-2016-10243

Date: Mon, 6 Mar 2017 16:49:27 -0500

On Mon, Mar 06, 2017 at 10:32:04PM +0100, Ricardo Wurmus wrote:
> 
> Leo Famulari <leo@famulari.name> writes:
> 
> > On Mon, Mar 06, 2017 at 10:02:06AM +0100, Ricardo Wurmus wrote:
> >> Is this sufficient?  I see here that two files need this change:
> >> 
> >>     https://www.tug.org/svn/texlive?view=revision&revision=42605
> >> 
> >> Should “trunk/Build/source/texk/kpathsea/texmf.cnf” also be patched?
> >
> > I inspected the built output of texlive, texlive-bin, and texlive-texmf,
> > and none of them include the texmf.cnf file for kpathsea.
> >
> > That file does exist in the source.
> >
> > AFAICT, the only .cnf file in our built package that whitelists mpost is
> > the one I patched.
> 
> Thank you for confirming this.  The patch looks good to me!

Thanks for your review!

Pushed as e20784e65efa7c783792e8a830d4b4aaf35750d5

By the way, I'd normally adjust the patch to use the default patch-level
of 'p1', and to include another, more descriptive, link about the bug.
But I lack the disk space to rebuild texlive again. Building it before
and after the bug-fix, for testing, used ~12 GB.

Message #24 received at 25993-done@debbugs.gnu.org (full text, mbox, reply):

From: Ricardo Wurmus <rekado@elephly.net>

To: 25993-done@debbugs.gnu.org

Subject: Re: bug#25993: texlive CVE-2016-10243

Date: Thu, 09 Mar 2017 09:14:32 +0100

> Pushed as e20784e65efa7c783792e8a830d4b4aaf35750d5

Closing.

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