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Message-ID: <56CEDD29.5050809@oracle.com>
Date: Thu, 25 Feb 2016 10:53:29 +0000
From: John Haxby <john.haxby@...cle.com>
To: oss-security@...ts.openwall.com
Subject: Re: CVE Request: bash-completion: dequote command
injection
On 24/02/16 21:58, Kurt Seifried wrote:
> I think in this case it's pretty simply "dequoting should not result in
> code execution" much like the various deserialization flaws (they should
> deserialize the data, not execute random stuff).
My immediate assumption was that an unprivileged user could leave
something lying around that root could complete on.
Within bash-completion, most of the uses of dequote are to find a config
file so there'd be a degree of social engineering to persuade root to
use a config file of your choice. The other main use seems to be in
_parse_help() and _parse_usage() which parse gnu-style help and
bsd-style usage respectively and that might not need as much social
engineering to exploit. I didn't investigate further.
Whether or not this turns out to be exploitable at all in
bash-completion, I do agree with Kurt though.
jch
>
> On Wed, Feb 24, 2016 at 2:56 PM, Fernando Muñoz <fernando@...l-life.com>
> wrote:
>
>> Hello Eric,
>>
>> I never mentioned privilege escalation.
>>
>> This issue how ever could appear when a different application uses
>> user input and calls "dequote" function that not only dequotes, but
>> also executes it as a command. If mitre doesn't consider it CVE worth,
>> that's OK!
>>
>> Regards.
>>
>>
>>
>> On Wed, Feb 24, 2016 at 3:58 PM, Eric Blake <eblake@...hat.com> wrote:
>>> On 02/24/2016 12:08 PM, Fernando Muñoz wrote:
>>>> Marcelo Echeverria and Fernando Muñoz discovered that the dequote
>>>> function included in bash-completion allows to execute arbitrary
>>>> commands since it uses the eval function to call printf and perform
>>>> the actual dequoting. bash-completion is included on Debian, Ubuntu
>>>> OpenSuse [1] and probably other distros.
>>>
>>> But what is the privilege escalation? This is no different than
>>> incorrectly using 'eval' in a shell script - you may have buggy code,
>>> and have an easy-to-trigger bug, but if you can't escalate privileges,
>>> how it is a CVE?
>>>
>>> --
>>> Eric Blake eblake redhat com +1-919-301-3266
>>> Libvirt virtualization library http://libvirt.org
>>>
>>
>
>
>
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