Table of contents:
- What are Kubernetes?
- What is the Kubernetes cluster?
- 7 steps to secure Kubernetes
Kubernetes becomes more vulnerable to new security threats and risks as it evolves and improves. Kubernetes security is becoming increasingly important. As a result of these flaws, securing a Kubernetes cluster has become an expedition for DevOps teams. It has several implementation types (on-premise, cloud-managed, hybrid, and others), numerous open-source supporting tools, and various configuration settings. The need to safeguard any security-sensitive architecture that runs container workloads too has grown.
According to CNCF’s Kubernetes security audit survey, attackers can carry out illegal acts by exploiting various Kubernetes vulnerabilities and several standard configurations. Today, we’ll look at some best practices for putting security measures in place.
What are Kubernetes?
Kubernetes is a system for managing containers (containerized applications), where a container can be thought of as a lightweight virtual machine. To create an application, you must first create some containers and use Kubernetes to manage those containers. It does have a vast and rapidly expanding ecosystem, and facilities, assistance, and tools for Kubernetes seem to be readily available. Kubernetes is a Greek word that means “helmsman” or “pilot.” K8s are derived from adding the eight letters between “K” and the “s.” Kubernetes can immediately produce and extend containers and manage storage across all containers.
To know in-depth about Containerization, Kubernetes training will help you a lot to gain deeper insights into the technology.
What exactly is a Kubernetes cluster?
Source ~ https://kubernetes.io/docs/concepts/overview/components/
A cluster is a Kubernetes system that contains all of the Kubernetes components. The cluster could even run on physical machines (like PCs or laptops) or as virtual machines. If you only have one machine running a full Kubernetes system, that machine hosts your Kubernetes cluster; whether you have two machines running Kubernetes, those two machines organize your Kubernetes cluster. The cluster can be run on any mix of physical and virtual machines.
7 steps to secure a Kubernetes cluster:
Let’s talk about the security best practices that enterprises should use to ensure the security of their Kubernetes clusters.
- Consider upgrading Kubernetes to the most recent version.
The most fundamental and frequently overlooked security best practice would be to maintain Kubernetes ecosystems up with the latest. Benefit from new security features and bug tracking updates, and variant releases. Furthermore, before launching to the production cluster, use the most recent full version in the testing environment.
- Authenticate Kubernetes API servers.
The Kubernetes API server, also recognized as Kube-API server, is the heart of a Kubernetes cluster. Kubernetes APIs are the primary point of access for a Kubernetes cluster. APIs can be accessed by admins or service accounts via the command-line utility kubectl, REST API calls, or other client SDKs. The server provides access and guarantees that the cluster is operational. All API attempts to call inside the cluster should use encrypted Transport Layer Security. Embrace an API authentication method for API servers in full compliance with the access control rules.
Simple certificates or a bearer token are the two most common authentication methods. To separate users into particular groups and the control group access, large-scale entrepreneurship clusters could perhaps incorporate third-party OpenID Connect providers or Lightweight Directory Access Protocol servers. For an overall view of how to make sure users and authentication strategies, see the official Kubernetes documentation.
- Enable authorization for role-based access control.
RBAC i.e, role-based access control mechanism that allows multiple applications to undertake concrete actions based on the minimum model and only start enforcing necessary permission. Administrators should follow the following Kubernetes RBAC best practices:
- Enabling RBAC in an API server with the –authorization-mode=RBAC parameter will enforce RBAC as a standard configuration for cluster security.
- Use dedicated customer service accounts for each application rather than the default service accounts created by Kubernetes. Dedicated service accounts allow administrators to enforce RBAC per application and provide better controls over the fine-grained permission provided to each application resource.
- Reduce the number of optional API server flags to reduce the API server’s attack surface area. Each flag facilitates specific facets of cluster management, which may or may not expose the API server. Reduce using the following optional flags:-
- insecure-bind-address, and
- RBAC policies should be updated and adjusted on a regular basis to avoid becoming obsolete. Start by removing any permissions that are no longer needed. This can be time-consuming, but it is well worth the effort to preserve production workloads.
- Enforce the least privileges for an RBAC system to be effective. When cluster administrators obey the Pareto principle, everybody does their job and assigns only the permissions needed to a user or application. No additional privileges should be granted, and wildcard verbs [“*”] or blanket access should be avoided.
- Increase node security.
Begin by hardening the security of the node on which the pods run:
- Standards and benchmarks for configuration. Configure the host in accordance with the security recommendations. Validate clusters using Center for Internet Security benchmarks associated with specific Kubernetes releases.
- Minimization of administrative access. Reduce the attack surface area on Kubernetes nodes by limiting administrative access.
- Isolation and constraints on nodes Execute specific pods on specific nodes or nodes. This ensures that the pods run on nodes with specific isolation and security settings.
Add tags to node objects to allow pods to specifically target nodes and thus control which nodes a pod could indeed access:
After applying the node label, add a node selector to the pod deployments so that the pod changes significantly to the selected node, as shown in the following YAML file:
- Control who has access to the kubelet.
The kubelet seems to be an operative that keeps running on each cluster node. It communicates with users via APIs that regulate the pods trying to run on the nodes and perform specific tasks. Unauthorized disclosure to the kubelet provides attackers with API access and can jeopardize node or cluster security.
To reduce the attack surface and prevent unauthorized access to the APIs via the kubelet, take the following steps:
- Before starting the kubelet, set the –anonymous-auth flag to false to disable anonymous access: —anonymous-auth=false.
- Begin the Kube-Episerver command with the —kubelet-client-certificate and —kubelet-client-key flags. This ensures that the API server authenticates to the kubelet and prevents anonymous requests.
- The kubelet provides a read-only API that administrators can use without logging in. Because this could expose potentially sensitive cluster information, administrators should close the read-only ports using the following command: —read-only-port=0.
- Configure namespaces and network policies.
Namespaces distinguish delicate workloads from nonsensitive workloads. While handling multiple namespaces can be difficult, this makes things simpler to implement security controls such as network policies on managing performance to regulate the flow of traffic to and from pods.
- Turn on audit logging.
Enable Kubernetes audit logs and supervise them for illicit behavior and suspected API calls. Kubernetes could even keep detailed records of cluster activities. Possible security issues are detected in audit logs almost instantly. An attacker, for example, attempting to brute force a password may create authentication and authorization logs. If they occur repeatedly, there may be a security concern.
Audit logs have always been disabled by mistake; to enable them, just use the Kubernetes audit policy, which allows administrators to configure one of four audit levels:
- None. Events that match this rule should not be logged.
- Metadata. Request metadata, such as the requesting user, timestamp, resource, and verb, should be logged.
- Request. Log event metadata as well as the request body but not the response body. This does not apply to requests for non-resources.
- RequestResponse. Keep track of event metadata, requests, and response bodies. This will not apply to requests for non-resources.
The majority of this information is tracked by Kubernetes audit logging, and simple incorporation with cluster API should allow you to send these logs to outer logging and storage solutions. It could also generate dashboards, suspicious behavior alerts, and reports for incident investigations.
To enable audit logs on Kubernetes clusters, follow the steps below:
- Begin by connecting to the master node via SSH.
- Generate an audit log policy file with the YAML below and save it as YAML:
- Establish a new directory here on the master node for audit logs, such as /Kube/audit logs/.
- To configure the Kube-API server to load the audit policy, go to /etc/Kubernetes/manifests/Kube-API server.YAML and add the -audit-policy-file flag to the policy YAML created in step 2. Alternatively, specify -audit-log-path to direct audit logs to a specific file.
- Save and close the file.
DevOps teams that rely on Kubernetes for their backend must be aware of all risks and attacks that a cluster and the Docker containers that can run within it may face. Because of the variety of attack vectors available, the constant advancement of technology, and the consistent, widespread adoption of this tool, intruders find it appealing to penetrate clusters. Securing a Kubernetes cluster is a difficult task. It is critical to keep a close eye on a set to detect system vulnerabilities or fraudulent behavior as soon as possible. Of course, this is a separate topic that requires further investigation.
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