TMA-KUBERNETES-1.2.25

Ensure that the --client-ca-file argument is set as appropriate

HighLevel 1Automatedkubernetes

Description

Setup TLS connection on the API server. Audited on control-plane nodes from the running process arguments (falls back to the kubeadm static pod manifest); SKIPs on nodes without that manifest.

How it is checked

Audit method: Shell command

shell

set -f
a=$(ps -eo args 2>/dev/null | grep -E '^([^ ]*/)?kube-apiserver( |$)' | head -n 1)
[ -n "$a" ] || a=$(sed -n 's/^[[:space:]]*-[[:space:]]*"\{0,1\}\(--[^"]*\)"\{0,1\}[[:space:]]*$/\1/p' /etc/kubernetes/manifests/kube-apiserver.yaml | tr '\n' ' ')
[ -n "$a" ] || exit 1
g() { printf '%s\n' "$a" | awk -v k="--$1" '{for(i=1;i<=NF;i++){if($i==k&&i<NF)v=$(i+1); else if(index($i,k"=")==1)v=substr($i,length(k)+2)}} END{if(v!="")print v}'; }
has() { printf '%s\n' "$a" | awk -v k="--$1" '{for(i=1;i<=NF;i++) if($i==k||index($i,k"=")==1) f=1} END{exit !f}'; }
ok=1
v=$(g client-ca-file); [ -n "$v" ] || { echo "noncompliant: --client-ca-file not set"; ok=0; }
if [ "$ok" -eq 1 ]; then echo compliant; fi

Expected output: compliant

How it is fixed

Fix method: Guidance or infrastructure patch

Follow the Kubernetes documentation and set up the TLS connection on the apiserver. Then, edit the API server pod specification file /etc/kubernetes/manifests/kube-apiserver.yaml on the master node and set the client certificate authority file. --client-ca-file=<path/to/client-ca-file>

Properties

Operating systems: Any
Tags: kubernetesapi-server
Reference: CIS Kubernetes Benchmark v2.1.0 - 1.2.25 Ensure that the --client-ca-file argument is set as appropriate

Check this host

Run this on a machine you are allowed to audit. The scan is read-only.

shell

tmaegis scan --target kubernetes