CVE-2020-8554

Public Exploit
Kubernetes man in the middle using LoadBalancer or ExternalIPs

Description

Kubernetes API server in all versions allow an attacker who is able to create a ClusterIP service and set the spec.externalIPs field, to intercept traffic to that IP address. Additionally, an attacker who is able to patch the status (which is considered a privileged operation and should not typically be granted to users) of a LoadBalancer service can set the status.loadBalancer.ingress.ip to similar effect.

Remediation

Workaround:

  • To restrict the use of external IPs we are providing an admission webhook container: k8s.gcr.io/multitenancy/externalip-webhook:v1.0.0. The source code and deployment instructions are published at https://github.com/kubernetes-sigs/externalip-webhook. Alternatively, external IPs can be restricted using OPA Gatekeeper. A sample ConstraintTemplate and Constraint can be found here: https://github.com/open-policy-agent/gatekeeper-library/tree/master/library/general/externalip.

Category

6.3
CVSS
Severity: Medium
CVSS 3.1 •
CVSS 2.0 •
EPSS 30.95% Top 5%
Third-Party Advisory github.com Third-Party Advisory google.com Third-Party Advisory oracle.com Third-Party Advisory oracle.com Third-Party Advisory oracle.com
Affected: Kubernetes Kubernetes
Published at:
Updated at:

References

Link Tags
https://groups.google.com/g/kubernetes-security-announce/c/iZWsF9nbKE8 third party advisory mailing list
https://github.com/kubernetes/kubernetes/issues/97076 third party advisory exploit
https://lists.apache.org/thread.html/rcafa485d63550657f068775801aeb706b7a07140a8ebbdef822b3bb3%40%3Ccommits.druid.apache.org%3E mailing list
https://lists.apache.org/thread.html/r0c76b3d0be348f788cd947054141de0229af00c540564711e828fd40%40%3Ccommits.druid.apache.org%3E mailing list
https://lists.apache.org/thread.html/rdb223e1b82e3d7d8e4eaddce8dd1ab87252e3935cc41c859f49767b6%40%3Ccommits.druid.apache.org%3E mailing list
https://lists.apache.org/thread.html/r1975078e44d96f2a199aa90aa874b57a202eaf7f25f2fde6d1c44942%40%3Ccommits.druid.apache.org%3E mailing list
https://www.oracle.com//security-alerts/cpujul2021.html third party advisory patch
https://www.oracle.com/security-alerts/cpujan2022.html third party advisory patch
https://www.oracle.com/security-alerts/cpuapr2022.html third party advisory patch

Frequently Asked Questions

What is the severity of CVE-2020-8554?
CVE-2020-8554 has been scored as a medium severity vulnerability.
How to fix CVE-2020-8554?
As a workaround for remediating CVE-2020-8554: To restrict the use of external IPs we are providing an admission webhook container: k8s.gcr.io/multitenancy/externalip-webhook:v1.0.0. The source code and deployment instructions are published at https://github.com/kubernetes-sigs/externalip-webhook. Alternatively, external IPs can be restricted using OPA Gatekeeper. A sample ConstraintTemplate and Constraint can be found here: https://github.com/open-policy-agent/gatekeeper-library/tree/master/library/general/externalip.
Is CVE-2020-8554 being actively exploited in the wild?
It is possible that CVE-2020-8554 is being exploited or will be exploited in a near future based on public information. According to its EPSS score, there is a ~31% probability that this vulnerability will be exploited by malicious actors in the next 30 days.
What software or system is affected by CVE-2020-8554?
CVE-2020-8554 affects Kubernetes Kubernetes.
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