1.2.34 Ensure that the API Server only makes use of Strong Cryptographic Ciphers

Information

Ensure that the API server is configured to only use strong cryptographic ciphers.

Rationale:

TLS ciphers have had a number of known vulnerabilities and weaknesses, which can reduce the protection provided by them. By default, Kubernetes supports a number of TLS ciphersuites including some that have security concerns, weakening the protection provided.

Impact:

API server clients that cannot support modern cryptographic ciphers will not be able to make connections to the API server.

Solution

Edit the API server pod specification file /etc/kubernetes/manifests/kube-apiserver.yaml on the master node and set the below parameter.

--tls-cipher-suites=TLS_AES_128_GCM_SHA256, TLS_AES_256_GCM_SHA384, TLS_CHACHA20_POLY1305_SHA256, TLS_ECDHE_ECDSA_WITH_AES_128_CBC_SHA, TLS_ECDHE_ECDSA_WITH_AES_128_GCM_SHA256, TLS_ECDHE_ECDSA_WITH_AES_256_CBC_SHA, TLS_ECDHE_ECDSA_WITH_AES_256_GCM_SHA384, TLS_ECDHE_ECDSA_WITH_CHACHA20_POLY1305, TLS_ECDHE_ECDSA_WITH_CHACHA20_POLY1305_SHA256, TLS_ECDHE_RSA_WITH_3DES_EDE_CBC_SHA, TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA, TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256, TLS_ECDHE_RSA_WITH_AES_256_CBC_SHA, TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384, TLS_ECDHE_RSA_WITH_CHACHA20_POLY1305, TLS_ECDHE_RSA_WITH_CHACHA20_POLY1305_SHA256, TLS_RSA_WITH_3DES_EDE_CBC_SHA, TLS_RSA_WITH_AES_128_CBC_SHA, TLS_RSA_WITH_AES_128_GCM_SHA256, TLS_RSA_WITH_AES_256_CBC_SHA, TLS_RSA_WITH_AES_256_GCM_SHA384.

Default Value:

By default, the Kubernetes API server supports a wide range of TLS ciphers

See Also

https://workbench.cisecurity.org/files/3891

Item Details

Category: CONFIGURATION MANAGEMENT

References: 800-53|CM-6, 800-53|CM-7, CSCv7|5.1

Plugin: Unix

Control ID: 8ebbd47f2964abc378f03889a573651043ef53b8c3ef7ac8df6d215d2c4ee3cb