services / Google Cloud / ReplicaSets

Control Kubernetes ReplicaSet objects.

ReplicaSets allow maintaining a desired number of replicas and handle situations like pod failures or manual scaling. Typically, ReplicaSets are not created directly but are managed by a Deployment. When that is the case, the ReplicaSet cannot be updated directly using the `update` endpoints. ReplicaSets expose very similar risks to Deployments, the key privilege being the ability to specify a container image to run in the Pods managed by the ReplicaSet. If coupled with a cluster that can connect to the internet, this opens up arbitrary code execution by fetching and running potentially malicious images. Secondly, creating or updating the replica count of ReplicaSets drains the limited resources available to other Kubernetes workloads.

container.​replicaSets.​create

Creation of standalone ReplicaSet allows running an image inside the Kubernetes cluster. This may allow arbitrary code execution, if the cluster has access to the public internet. Secondly, creating ReplicaSets drains the limited resources available to other Kubernetes workloads.

Risks

1. Data exfiltration (CRITICAL)
2. Lateral movement (BOOST)
3. Network movement (BOOST)
4. Resource hijacking (MEDIUM)
5. Spend (MEDIUM)

Scope: MEDIUM

This privilege may grant access to confidential data, or its exploit can incur operational cost.