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. Download attachment "signature.asc" of type "application/pgp-signature" (497 bytes)
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