CVE-2016-0634 code execution in Bash prompt when expanding hostname

CVE-2016-0634 code execution in Bash prompt when expanding hostname

[Leo Famulari]

Any advice on how we should handle CVE-2016-0634?

http://seclists.org/oss-sec/2016/q3/534

Re: CVE-2016-0634 code execution in Bash prompt when expanding hostname

[John Darrington]

[-- Attachment #1: Type: text/plain, Size: 599 bytes --]

On Tue, Sep 20, 2016 at 04:55:30PM -0400, Leo Famulari wrote:
     Any advice on how we should handle CVE-2016-0634?
     
     http://seclists.org/oss-sec/2016/q3/534

Like the comment there says, it is only a problem if the machine has already been owned, so I don't
see what the issue is.  If there is an issue it is for the bash maintainers to patch.

J'

-- 
Avoid eavesdropping.  Send strong encrypted email.
PGP Public key ID: 1024D/2DE827B3 
fingerprint = 8797 A26D 0854 2EAB 0285  A290 8A67 719C 2DE8 27B3
See http://sks-keyservers.net or any PGP keyserver for public key.


[-- Attachment #2: Digital signature --]
[-- Type: application/pgp-signature, Size: 181 bytes --]

Re: CVE-2016-0634 code execution in Bash prompt when expanding hostname

[Ludovic Courtès]

John Darrington <john@darrington.wattle.id.au> skribis:

> On Tue, Sep 20, 2016 at 04:55:30PM -0400, Leo Famulari wrote:
>      Any advice on how we should handle CVE-2016-0634?
>      
>      http://seclists.org/oss-sec/2016/q3/534
>
> Like the comment there says, it is only a problem if the machine has
> already been owned,

… or if a privilege application like a DHCP client can be made to set
the host name to $(something bad), which was apparently possible at some
point.

> so I don't see what the issue is.  If there is an issue it is for the
> bash maintainers to patch.

Chet proposed a patch:

  http://seclists.org/oss-sec/2016/q3/att-538/prompt-string-comsub.patch

IIUC, the just-released 4.4 isn’t affected, right?

We should at least update it in core-updates, but core-updates won’t be
merged until we have fixed that Binutils/MIPS issue (which shouldn’t be
too hard, but we never know!).

I’m somewhat unavailable these days; could someone look into it?

Thanks for the heads-up Leo, as usual!

Ludo’.

Re: CVE-2016-0634 code execution in Bash prompt when expanding hostname

[Leo Famulari]

On Thu, Sep 22, 2016 at 12:42:15AM +0900, Ludovic Courtès wrote:
> John Darrington <john@darrington.wattle.id.au> skribis:
> 
> > On Tue, Sep 20, 2016 at 04:55:30PM -0400, Leo Famulari wrote:
> >      Any advice on how we should handle CVE-2016-0634?
> >      
> >      http://seclists.org/oss-sec/2016/q3/534
> >
> > Like the comment there says, it is only a problem if the machine has
> > already been owned,
> 
> … or if a privilege application like a DHCP client can be made to set
> the host name to $(something bad), which was apparently possible at some
> point.
> 
> > so I don't see what the issue is.  If there is an issue it is for the
> > bash maintainers to patch.

Perhaps it's not the most critical bug, but I don't think we can
effectively anticipate the full impact of this (or any) bug. It's better
to just fix it now that we know about it.

> Chet proposed a patch:
> 
>   http://seclists.org/oss-sec/2016/q3/att-538/prompt-string-comsub.patch

I've asked Chet if he will add the patch to the bash-4.3-patches FTP
directory. If not, we can apply it the "normal" way.

> 
> IIUC, the just-released 4.4 isn’t affected, right?

Right.

> We should at least update it in core-updates, but core-updates won’t be
> merged until we have fixed that Binutils/MIPS issue (which shouldn’t be
> too hard, but we never know!).

I spent some time looking at the Bash package definition, but I'm stuck
on how to handle all the Bash %patch-series machinery. There are
currently no patches for Bash 4.4, nor is there an FTP directory
corresponding to a future patch series.

Does anyone have advice on how to proceed?

Bash 4.4 upgrade

[Ludovic Courtès]

Hi!

Leo Famulari <leo@famulari.name> skribis:

> I spent some time looking at the Bash package definition, but I'm stuck
> on how to handle all the Bash %patch-series machinery. There are
> currently no patches for Bash 4.4, nor is there an FTP directory
> corresponding to a future patch series.
>
> Does anyone have advice on how to proceed?

I started looking at it and will probably push something Real Soon
(turned out to be trickier than I thought because of various changes in
what “make install” does.)

The ‘patch-series’ machinery is quite simple: we list the patches with a
number and their hash, and that’s it.  For 4.4, it’s just the empty
list.

Ludo’.

Re: Bash 4.4 upgrade

[Leo Famulari]

On Fri, Sep 30, 2016 at 06:17:42PM +0200, Ludovic Courtès wrote:
> Hi!
> 
> Leo Famulari <leo@famulari.name> skribis:
> 
> > I spent some time looking at the Bash package definition, but I'm stuck
> > on how to handle all the Bash %patch-series machinery. There are
> > currently no patches for Bash 4.4, nor is there an FTP directory
> > corresponding to a future patch series.
> >
> > Does anyone have advice on how to proceed?
> 
> I started looking at it and will probably push something Real Soon
> (turned out to be trickier than I thought because of various changes in
> what “make install” does.)

Sounds good. There is also readline 7.0, which I would have pushed to
core-updates at the same time as Bash.

Re: Bash 4.4 upgrade

[Ludovic Courtès]

Leo Famulari <leo@famulari.name> skribis:

> On Fri, Sep 30, 2016 at 06:17:42PM +0200, Ludovic Courtès wrote:
>> Hi!
>> 
>> Leo Famulari <leo@famulari.name> skribis:
>> 
>> > I spent some time looking at the Bash package definition, but I'm stuck
>> > on how to handle all the Bash %patch-series machinery. There are
>> > currently no patches for Bash 4.4, nor is there an FTP directory
>> > corresponding to a future patch series.
>> >
>> > Does anyone have advice on how to proceed?
>> 
>> I started looking at it and will probably push something Real Soon
>> (turned out to be trickier than I thought because of various changes in
>> what “make install” does.)
>
> Sounds good. There is also readline 7.0, which I would have pushed to
> core-updates at the same time as Bash.

Pushed as c573f5a5a5395d6b5cee3d06cbbc6a19573cf542.  Hydra will start
building it soon.

Ludo’.