[Security Advisory] CVE-2023-2878: secrets-store-csi-driver discloses service account tokens in logs

[Monis Khan]

Hello Kubernetes Community,

A security issue was discovered in secrets-store-csi-driver where an actor with access to the driver logs could observe service account tokens.  These tokens could then potentially be exchanged with external cloud providers to access secrets stored in cloud vault solutions.  Tokens are only logged when TokenRequests is configured in the CSIDriver object and the driver is set to run at log level 2 or greater via the -v flag.

This issue has been rated MEDIUM CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:N/A:N (6.5), and assigned CVE-2023-2878

Am I vulnerable?

You may be vulnerable if TokenRequests is configured in the CSIDriver object and the driver is set to run at log level 2 or greater via the -v flag.

To check if token requests are configured, run the following command:

kubectl get csidriver secrets-store.csi.k8s.io -o jsonpath="{.spec.tokenRequests}"

To check if tokens are being logged, examine the secrets-store container log:

kubectl logs -l app=secrets-store-csi-driver -c secrets-store -f | grep --line-buffered "csi.storage.k8s.io/serviceAccount.tokens"

Affected Versions

- secrets-store-csi-driver < 1.3.3

How do I mitigate this vulnerability?

Prior to upgrading, this vulnerability can be mitigated by running secrets-store-csi-driver at log level 0 or 1 via the -v flag.

Fixed Versions

- secrets-store-csi-driver >= 1.3.3

To upgrade, refer to the documentation: https://secrets-store-csi-driver.sigs.k8s.io/getting-started/upgrades.html#upgrades

Detection

Examine cloud provider logs for unexpected token exchanges, as well as unexpected access to cloud vault secrets.

If you find evidence that this vulnerability has been exploited, please contact secu...@kubernetes.io

Acknowledgements

This vulnerability was reported by Tomer Shaiman @tshaiman from Microsoft.

Thank You,

Mo Khan on behalf of the Kubernetes Security Response Committee