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Message-ID: <B760F07C-908F-431A-8BCE-A3AE9E93E33F@nccgroup.trust>
Date: Wed, 27 Jul 2016 16:26:37 -0400
From: Jesse Hertz <jesse.hertz@...group.trust>
To: <oss-security@...ts.openwall.com>
Subject: Re: cve request: systemd-machined: information exposure for docker containers
Just to chime in here, since a docker container would be inside its own PID namespace, running ‘ps’ inside a container would not show you other processes/containers running on the same host.
A similar “vulnerability" I “found” was patched in Docker earlier (tl;dr '/proc/sched_debug’ is not pid namespace aware).
-jh
> On Jul 27, 2016, at 4:00 PM, Christian Rebischke <Chris.Rebischke@...hlinux.org> wrote:
>
> On Wed, Jul 27, 2016 at 01:27:08PM -0400, Daniel J Walsh wrote:
>>
>>
>> On 07/27/2016 01:05 PM, Christian Rebischke wrote:
>>> On Tue, Jul 26, 2016 at 03:24:13PM -0400, cve-assign@...re.org wrote:
>>>> -----BEGIN PGP SIGNED MESSAGE-----
>>>> Hash: SHA256
>>>>
>>>>> Once docker containers register themselves to systemd-machined
>>>>> by oci-register-machine. Any unprivileged user could run
>>>>> machinectl to list every single containers running in the host
>>>>> even if the containers do not belong to this user (including containers
>>>>> belong to the root user), and access sensitive information associated
>>>>> with any individual container including its internal IP address, OS
>>>>> version, running processes, and file path for its rootfs.
>>>>>
>>>>> $ machinectl status cc8d10c7b9892b75843d200d54d34a3a
>>>>> cc8d10c7b9892b75843d200d54d34a3a(63633864313063376239383932623735)
>>>>> Since: Mon 2016-07-25 17:55:36 UTC; 34s ago
>>>>> Leader: 43494 (sleep)
>>>>> Service: docker; class container
>>>>> Root: /var/mnt/overlay/overlay/0429684e3da515ae4f11b8514c7b20f759613
>>>>> Address: 172.17.0.2
>>>>> fe80::42:acff:fe11:2
>>>>> OS: Red Hat Enterprise Linux Server 7.2 (Maipo)
>>>>> Unit: docker-cc8d10c7b9892b75843d200d54d34a3a9435fe0f65527c254ebfd2d
>>>>> 43494 sleep 3000
>>>> Use CVE-2016-6349.
>>> Hello,
>>> I don't think that the bug for this problem lies in systemd.
>>> It's more a design mistake in docker or oci-register-machine.
>>> I have forwarded this issue to the systemd developer team and I don't
>>> think they will fix this in the future. In their opinion it's a
>>> bug in docker or oci-register-machine:
>>>
>>> https://github.com/systemd/systemd/issues/3815
>>>
>>> by the way.. I would feel glad if the security researchers would first
>>> message the developers and then assign a CVE a bug. This is the normal
>>> way for a full disclosure.
>>>
>>> best regards,
>>>
>>> Christian Rebischke
>> Why is this a bug in oci-register-machine? All it is doing is calling
>> the systemd-machine call to register with it using the three flags
>> available.
>> Is systemd saying we should not use that call?
>
> Let me quote Lennart Poettering:
>
> ---
> machined is a system service and is for registering containers running
> on the system. There's no concept of "user containers" with that, and
> unprivileged users do not have the privileges to even register any
> containers with machined.
>
> If you ask me the CVE is complete and utter rubbish. At least against
> systemd. If Docker knows a concept of user containers, then good for
> them, but in that case they shouldn't register them with machined
> really, if they are not supposed to be visible on the host.
>
> Generally though I think the CVE is without merit entirely, after all
> "ps" is generally unrestricted, and hence you can always see container
> processes running on the host anyway.
> ---
>
> In my opinion I would say you shouldn't use this call if you don't want
> an information leak. Even if systemd would fix the output of
> `machinectl status ..`. The information leak would still be there
> because you could still see informations about the container with `ps`
> or other tools. systemd is not designed for 'user containers'.
>
> If yo have further questions. I would say that you ask the
> systemd-developers on their mailing list directly.
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