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kubernetes

API server pod has the --etcd-cafile argument set

apiserver_etcd_cafile_set
Service: apiserverSeverity: critical
OfficialBuilt-inVerified
Categories:encryptioncluster-security
Resource Type:Pod

Kubernetes API server uses an etcd CA file via --etcd-cafile to verify etcd's TLS certificate.

This evaluates whether API server containers specify that CA file, anchoring TLS trust for etcd connections.

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Risk

Without a validated etcd CA, the API server may accept rogue or intercepted endpoints, undermining:

  • Confidentiality: exposure of cluster data in transit
  • Integrity: tampering with Kubernetes state in etcd
  • Availability: control plane disruption via malicious etcd responses

Run this check with Prowler

Run in Prowler Cloud
Run
prowler kubernetes --checks apiserver_etcd_cafile_set

Recommendation

Anchor etcd connections in mutual TLS: provide a trusted CA (--etcd-cafile) and unique client credentials, rotate keys, and prefer strong ciphers.

Apply least privilege and network segmentation so only API servers can reach etcd; disable plaintext or unauthenticated access.

Remediation

Other

1SSH to the control plane node running kube-apiserver
2Edit /etc/kubernetes/manifests/kube-apiserver.yaml
3In spec.containers[0].command, add the flag line:
4```
5- --etcd-cafile=/etc/kubernetes/pki/etcd/ca.crt
6```
7Save the file; the kubelet will restart the API server automatically

Check Code

from prowler.lib.check.models import Check, Check_Report_Kubernetes
from prowler.providers.kubernetes.services.apiserver.apiserver_client import (
    apiserver_client,
)


class apiserver_etcd_cafile_set(Check):
    def execute(self) -> Check_Report_Kubernetes:
        findings = []
        for pod in apiserver_client.apiserver_pods:
            report = Check_Report_Kubernetes(metadata=self.metadata(), resource=pod)
            report.status = "PASS"
            report.status_extended = (
                f"etcd CA file is set appropriately in pod {pod.name}."
            )
            etcd_cafile_set = True
            for container in pod.containers.values():
                # Check if "--etcd-cafile" is set
                if "--etcd-cafile" not in str(container.command):
                    etcd_cafile_set = False
                    break

            if not etcd_cafile_set:
                report.status = "FAIL"
                report.status_extended = f"etcd CA file is not set in pod {pod.name}."

            findings.append(report)
        return findings

References