CVE-2018-1085
Find out more about CVE-2018-1085 from the MITRE CVE dictionary dictionary and NIST NVD.
Statement
This issue affects Openshift Container Platform (OCP) only if you use the container installation method. The container installation method is tech preview in 3.7.1. This issue affected all users who did a containerized etcd in OCP versions 3.7.1-3.6.
If etcd is installed via RPM and run via '/usr/bin/etcd' it's not affected by this flaw. You can check if etcd is being run from '/usr//bin/etcd' using a 'ps' command such as this on the master nodes. If Installed via RPM you should get output similar to:
ps -ef | grep etcd
$/usr/bin/etcd --name=master-0.example.com --data-dir=/var/lib/etcd/ --listen-client-urls=https://10.0.1.1:2379
If etcd is installed via the container method running 'docker ps' on the master will show a container running the registry.access.redhat.com/rhel7/etcd image, eg:
sudo docker ps --filter name=etcd_container
$704effa9b0cc registry.access.redhat.com/rhel7/etcd "/usr/bin/etcd" 56 minutes ago Up 56 minutes etcd_container
CVSS v3 metrics
| CVSS3 Base Score | 9 |
|---|---|
| CVSS3 Base Metrics | CVSS:3.0/AV:A/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H |
| Attack Vector | Adjacent Network |
| Attack Complexity | Low |
| Privileges Required | Low |
| User Interaction | None |
| Scope | Changed |
| Confidentiality | High |
| Integrity Impact | High |
| Availability Impact | High |
Red Hat Security Errata
| Platform | Errata | Release Date |
|---|---|---|
| Red Hat OpenShift Container Platform 3.9 (openshift-ansible) | RHSA-2018:2013 | 2018-06-27 |
Acknowledgements
Red Hat would like to thank David Hocky (Comcast) for reporting this issue.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 -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.