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cilium-agent container can access the host via `hostPath` mount

Moderate
nebril published GHSA-4hc4-pgfx-3mrx Mar 17, 2023

Package

gomod cilium-agent (Go)

Affected versions

<=1.11.14, <=1.12.7, 1.13.0

Patched versions

1.11.15, 1.12.8, 1.13.1

Description

Impact

An attacker with access to a Cilium agent pod can write to /opt/cni/bin due to a hostPath mount of that directory in the agent pod. By replacing the CNI binary with their own malicious binary and waiting for the creation of a new pod on the node, the attacker can gain access to the underlying node.

Patches

The issue has been fixed and is available on versions >=1.11.15, >=1.12.8, >=1.13.1.

Workarounds

Kubernetes RBAC should be used to deny users and service accounts exec access to Cilium agent pods.

In cases where a user requires exec access to Cilium agent pods, but should not have access to the underlying node, no workaround is possible.

References

Acknowledgements

The Cilium community has worked together with members of Isovalent and Form3 to prepare these mitigations. Special thanks to Anastasios Koutlis, Daniel Teixeira, and Magdalena Oczadly for their cooperation.

For more information

If you have any questions or comments about this advisory, please reach out on Slack.

As usual, if you think you found a related vulnerability, we strongly encourage you to report security vulnerabilities to our private security mailing list: security@cilium.io - first, before disclosing them in any public forums. This is a private mailing list where only members of the Cilium internal security team are subscribed to, and is treated as top priority.

Severity

Moderate
4.4
/ 10

CVSS base metrics

Attack vector
Local
Attack complexity
Low
Privileges required
High
User interaction
None
Scope
Unchanged
Confidentiality
None
Integrity
None
Availability
High
CVSS:3.1/AV:L/AC:L/PR:H/UI:N/S:U/C:N/I:N/A:H

CVE ID

CVE-2023-27593

Weaknesses

Credits