cis-ocp-v170-1-2-25

name	cis-ocp-v170-1.2.25
description	Ensure that the --service-account-lookup argument is set to true (Manual)
category	cis-openshift
version	1.7.0
author	cyberstrike-official
tags	["cis","openshift","kubernetes","redhat","control-plane","api-server"]
cis_id	1.2.25
cis_benchmark	CIS Red Hat OpenShift Container Platform Benchmark v1.7.0
tech_stack	["kubernetes","openshift","redhat"]
cwe_ids	[]
chains_with	[]
prerequisites	[]
severity_boost	{}

CIS Red Hat OpenShift Container Platform Benchmark v1.7.0 - Control 1.2.25

Profile Applicability

• Level: 1

Description

Validate service account before validating token.

Rationale

If --service-account-lookup is not enabled, the apiserver only verifies that the authentication token is valid, and does not validate that the service account token mentioned in the request is actually present in etcd. This allows using a service account token even after the corresponding service account is deleted. This is an example of time of check to time of use security issue.

Impact

None.

Audit Procedure

OpenShift denies access for any OAuth Access token that does not exist in its etcd data store. OpenShift does not use the service-account-lookup flag even when it is set.

Run the following command:

oc get configmap config -n openshift-kube-apiserver -ojson | jq -r '.data["config.yaml"]' | jq '.apiServerArguments."service-account-lookup"[]'

Verify that if the --service-account-lookup argument exists it is set to true.

Remediation

None.

Default Value

Service account lookup is enabled by default.

References

1. https://docs.openshift.com/container-platform/latest/operators/operator-reference.html#kube-apiserver-operator_red-hat-operators
2. https://docs.openshift.com/container-platform/latest/operators/operator-reference.html#openshift-apiserver-operator_red-hat-operators
3. https://kubernetes.io/docs/reference/command-line-tools-reference/kube-apiserver/
4. https://github.com/kubernetes/kubernetes/issues/24167
5. https://en.wikipedia.org/wiki/Time-of-check_to_time-of-use

CIS Controls

Controls Version