CVE-2018-1085

OpenShift and Atomic Enterprise Ansible deploys a misconfigured etcd file that causes the SSL client certificate authentication to be disabled. Quotations around the values of ETCD_CLIENT_CERT_AUTH and ETCD_PEER_CLIENT_CERT_AUTH in etcd.conf result in etcd being configured to allow remote users to connect without any authentication if they can access the etcd server bound to the network on the master nodes. An attacker could use this flaw to read and modify all the data about the Openshift cluster in the etcd datastore, potentially adding another compute node, or bringing down the entire cluster.

Mitigation

On master nodes where etcd has been installed using the container method:

0. Verify you can connect to etcd without providing TLS authentication credentials. On any master node, check the ETCD_LISTEN_CLIENT_URLS in /etc/etcd/etcd.conf, and use one of the client urls to connect without providing a certificate, eg:
curl -4 curl <https://10.0.1.1:2379/version&gt; -k

0a. If vulnerable output will show something like this:
{"etcdserver":"3.2.15","etcdcluster":"3.2.0"}

0b. If not affected the connection will fail with:
curl: (58) NSS: client certificate not found (nickname not specified)

1. update /etc/etcd/etcd.conf on the master nodes to remove quotes from these fields:
ETCD_PEER_CLIENT_CERT_AUTH="true"
ETCD_CLIENT_CERT_AUTH="true"
eg.
ETCD_PEER_CLIENT_CERT_AUTH=true
ETCD_CLIENT_CERT_AUTH=true

2. Restart the etcd container service:
sudo systemctl restart etcd_container

3. Test if client authentication is now required using the steps from 0. above.