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Check: CNTR-K8-002640

Kubernetes STIG: CNTR-K8-002640 (in versions v1 r11 through v1 r7)

Title

Kubernetes endpoints must use approved organizational certificate and key pair to protect information in transit. (Cat I impact)

Discussion

Kubernetes control plane and external communication is managed by API Server. The main implementation of the API Server is to manage hardware resources for pods and container using horizontal or vertical scaling. Anyone who can gain access to the API Server can effectively control your Kubernetes architecture. Using authenticity protection, the communication can be protected against man-in-the-middle attacks/session hijacking and the insertion of false information into sessions. The communication session is protected by utilizing transport encryption protocols, such as TLS. TLS provides the Kubernetes API Server with a means to be able to authenticate sessions and encrypt traffic. By default, the API Server does not authenticate to the kubelet HTTPs endpoint. To enable secure communication for API Server, the parameter -kubelet-client-certificate and kubelet-client-key must be set. This parameter gives the location of the certificate and key pair used to secure API Server communication.

Check Content

Change to the /etc/kubernetes/manifests/ directory on the Kubernetes Control Plane. Run the command: grep -i kubelet-client-certificate * grep -I kubelet-client-key * If the setting "--kubelet-client-certificate" is not configured in the Kubernetes API server manifest file or contains no value, this is a finding. If the setting "--kubelet-client-key" is not configured in the Kubernetes API server manifest file or contains no value, this is a finding.

Fix Text

Edit the Kubernetes API Server manifest file in the /etc/kubernetes/manifests directory on the Kubernetes Control Plane. Set the value of "--kubelet-client-certificate" and "--kubelet-client-key" to an Approved Organizational Certificate and key pair.

Additional Identifiers

Rule ID: SV-245544r918217_rule

Vulnerability ID: V-245544

Group Title: SRG-APP-000439-CTR-001080

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CCIs

CCIs tied to check.

Number	Definition
CCI-002448	The organization distributes asymmetric cryptographic keys using: NSA-approved key management technology and processes; approved PKI Class 3 certificates or prepositioned keying material; or approved PKI Class 3 or Class 4 certificates and hardware security tokens that protect the user^s private key.

Controls

Controls tied to check. These are derived from the CCIs shown above.

Number	Title
SC-12 (3)	Asymmetric Keys