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Date: Thu, 22 Aug 2013 18:26:01 -0600
From: Kurt Seifried <kseifried@...hat.com>
To: Daniel Kahn Gillmor <dkg@...thhorseman.net>
CC: oss-security@...ts.openwall.com, Andrey Korolyov <andrey@...l.ru>
Subject: Re: Possibly insecure permissions on sshd_config in
Debian-based distros
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On 08/22/2013 03:07 PM, Daniel Kahn Gillmor wrote:
> On 08/22/2013 04:36 PM, Andrey Korolyov wrote:
>> On Fri, Aug 23, 2013 at 12:20 AM, Kurt Seifried
>> <kseifried@...hat.com> wrote:
>
>>> Well the default file config would of course be known. I'm
>>> reading the man page and nothing super secret pops out, e.g. no
>>> passwords get embedded. Can you give an example of sensitive
>>> information in sshd_config?
>>
>> AllowUsers/AllowGroups/PermitEmptyPasswords
>>
>> Obtaining such information can shorten time of bruteforce remote
>> attacks.
>
> I don't think these rise to the level of being worth hiding at
> all.
>
> PermitEmptyPasswords is one additional password to test against
> each user account, which i don't think is significant. And a user
> with local access to the machine can already radically shorten
> bruteforce enumeration of possible accounts with just with "getent
> passwd". the gap from there to AllowUsers isn't particularly
> significant by comparison.
>
> I don't know of any history of any serious high-entropy secrets
> (passphrases, secret keys, etc) being stored in sshd_config, and i
> would imagine the ssh developers would resist any configuration
> that encourages that sort of thing.
>
> Having your config files world-readable by default eases debugging,
> and can communicate to savvy users what your policies are without
> needing to exchange e-mail or chat.
>
> Administrators who want to make that tradeoff are free to make it,
> of course, but if a proposal was made within debian to do something
> like "chmod go-r sshd_config", i would object to it.
>
> This doesn't warrant a CVE.
>
> --dkg
Yup, the information would help a bit, but not enough to warrant a CVE
I think. Unless someone comes up with something new for this no CVE.
- --
Kurt Seifried Red Hat Security Response Team (SRT)
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