oss-sec mailing list archives
Re: Re: cve request: docker swarmkit Dos occurs by repeatly joining and quitting swam cluster as a node
From: Kurt Seifried <kseifried () redhat com>
Date: Fri, 2 Sep 2016 11:24:13 -0600
On Thu, Sep 1, 2016 at 9:30 PM, Diogo Mónica <diogo.monica () docker com> wrote:
If you read the report, you'll see that no claims are made about shutting down the swarm. The reporter simply claims that no new nodes can join the swarm: "it results in a machine could not join the swarm cluster after another node’s repeatedly joining and quitting the swarm"
As we describe in our documentation, possession of the token gives the permission to join new workers. Joining new workers effectively means reserving some resources for your worker. If the system runs out of resources, I believe it is expected that no new workers should be able to join.
DoS is often a gray area. Obviously if I send 10 gigabits of request traffic and swarm gets slow/non responsive the CVE response would be "Well yeah... that's probably what happens if you saturate the network with requests. No CVE for you" but if a single node behaves in an odd way and prevents the whole system from working in an expected manner, that may be a problem that is worth a CVE, especially if it can be triggered by an attacker/less trusted user (classic trust boundary violation to quote @sushidude).
Again, this is simply not a vulnerability of either Docker swarm or Docker swarmkit, and I kindly request that this CVE is rescinded.
Regardless of whether this is CVE worthy is there any plan to add rate limiting or other protective measures to prevent a single badly behaved/malicious node from making the swarm unable to operate normally? I don't see any issues in https://github.com/docker/swarm/issues for this. Thanks!
On Thu, Sep 1, 2016 at 7:53 PM, Kurt Seifried <kseifried () redhat com> wrote:On Thu, Sep 1, 2016 at 8:48 PM, Diogo Monica <diogo.monica () docker com> wrote:Can you please describe how this vulnerability makes a worker node beableto administer the swarm?It allows a worker node to disable and effectively shut down the swarm, I assume shutting down the swan is an administrative function, if notpleaselet me know where the documentation for workers covers this (allowing a worker to shutdown the swarm). Thanks!On Thu, Sep 1, 2016 at 7:12 PM -0700, "Kurt Seifried" < kseifried () redhat com> wrote: On Thu, Sep 1, 2016 at 5:17 PM, Diogo Mónica wrote:A few weeks ago (Aug 4, 2016), a CVE (CVE-2016-6595) describing a DoSondocker swarm got issued. We believe this not a real issue, and wouldliketo have the CVE rescinded. The person reporting this "vulnerability" is exhausting the resourcesofaremote manager by doing hundreds of join/leave operations withoutremovingthe state that is left by old nodes. At some point the managerobviouslystops being able to accept new nodes, since it runs out of memory. Given that both for Docker swarm and for Docker Swarmkit nodes are *required* to provide a secret token (it's actually the only mode of operation), this means that no adversary can simply join nodes andexhaustmanager resources. We can't do anything about a manager running out of memory and notbeingable to add new legitimate nodes to the system. This is merely aresourceprovisioning issue, and definitely not a CVE worthy vulnerability.I checked the documentation and it looks like a worker node is only supposed to work and is not supposed to be able to administer theswarm.Assuch this is a trust boundary violation, and needs a CVE.Thank you, -- Diogo Mónica-- -- Kurt Seifried -- Red Hat -- Product Security -- Cloud PGP A90B F995 7350 148F 66BF 7554 160D 4553 5E26 7993 Red Hat Product Security contact: secalert () redhat com-- -- Kurt Seifried -- Red Hat -- Product Security -- Cloud PGP A90B F995 7350 148F 66BF 7554 160D 4553 5E26 7993 Red Hat Product Security contact: secalert () redhat com-- Diogo Mónica
-- -- Kurt Seifried -- Red Hat -- Product Security -- Cloud PGP A90B F995 7350 148F 66BF 7554 160D 4553 5E26 7993 Red Hat Product Security contact: secalert () redhat com
Current thread:
- cve request: docker swarmkit Dos occurs by repeatly joining and quitting swam cluster as a node 张开翔 (Jul 29)
- Re: cve request: docker swarmkit Dos occurs by repeatly joining and quitting swam cluster as a node cve-assign (Aug 03)
- <Possible follow-ups>
- Re: cve request: docker swarmkit Dos occurs by repeatly joining and quitting swam cluster as a node Diogo Mónica (Sep 01)
- Re: Re: cve request: docker swarmkit Dos occurs by repeatly joining and quitting swam cluster as a node Kurt Seifried (Sep 01)
- Re: Re: cve request: docker swarmkit Dos occurs by repeatly joining and quitting swam cluster as a node Diogo Monica (Sep 01)
- Re: Re: cve request: docker swarmkit Dos occurs by repeatly joining and quitting swam cluster as a node Kurt Seifried (Sep 01)
- Re: Re: cve request: docker swarmkit Dos occurs by repeatly joining and quitting swam cluster as a node Diogo Mónica (Sep 02)
- Re: Re: cve request: docker swarmkit Dos occurs by repeatly joining and quitting swam cluster as a node Kurt Seifried (Sep 02)
- Re: Re: cve request: docker swarmkit Dos occurs by repeatly joining and quitting swam cluster as a node Diogo Mónica (Sep 05)
- Re: Re: cve request: docker swarmkit Dos occurs by repeatly joining and quitting swam cluster as a node Kurt Seifried (Sep 01)