Karmada PULL Mode Cluster Privilege Escalation

Summary

Karmada is a Kubernetes management system that allows users to run cloud-native applications across multiple Kubernetes clusters and clouds. Prior to version 1.12.0, the PULL mode clusters registered with the `karmadactl register` command have excessive privileges to access control plane resources. By abusing these permissions, an attacker able to authenticate as the karmada-agent to a karmada cluster would be able to obtain administrative privileges over the entire federation system including all registered member clusters. Since Karmada v1.12.0, command `karmadactl register` restricts the access permissions of pull mode member clusters to control plane resources. This way, an attacker able to authenticate as the karmada-agent cannot control other member clusters in Karmada. As a workaround, one may restrict the access permissions of pull mode member clusters to control plane resources according to Karmada Component Permissions Docs.