Kubescape and Kubernetes Hardening Guidance by N*A
https://github.com/armosec/kubescape
Disclaimer: Watch out this link redirects to a US .gov page, better use TOR or something! Just saying.
https://media.defense.gov/2021/Aug/03/2002820425/-1/-1/1/CTR_KUBERNETES%20HARDENING%20GUIDANCE.PDF