First published: 03 Jun 2024
Last modified: 19 Sep 2024
Author CKA: Vincenzo Tagliavia (CKA, CKAD, CKS)
This article does not prescribe security solutions, nor does it serve as a step-by-step guide to fixing specific Kubernetes cluster vulnerabilities.
Although security is a big issue when it comes to Kubernetes developments, many security reports coming from highly-reputable organizations all converge to similar results: misconfiguration is the top reason security breaches occur.
We want to offer a different, more holistic approach to Kubernetes security.
Since Kubernetes runs primarily in user-space, but all the workloads communicate with the Kernel via various “Interfaces” (e.g. the Container Runtime Interface and Container Networking Interface), we must view security with different lenses. The “whole” is made of a lot of different components, but to simplify (and we love simplicity), we dissect it into three main layers:
The issue with Kubernetes security isn’t just at the orchestrator layer. For example, each individual component in the Control Plane (e.g. Kubernetes API Server, ETCD, Controllers, etc.) interact with other components not necessarily bound to the same context layer. A request to the API server hits ETCD as well as workloads in other nodes, which in turn communicate with the Kernel and the underlying hardware via a number of different Interfaces, Drivers, Libraries, etc. See? We quickly lost simplicity, despite the fact we love it.
Kubernetes isn’t less secure than any other technology in the marketplace that is treated with insufficient care or lack of knowledge. The better your team’s knowledge around Kubernetes, the better your awareness and security posture will be.
Data coming from reputable sources would indicate that misconfiguration is the top reason for security breaches. These misconfigurations are preventable if you possess the know-how and prioritize security in your organization. Prioritize security via implementing internal policies and appropriate processes, such as DevSecOps, GitOps, and ZeroTrust Architecture.
At a Glance:
Misconfigurations: Lack of specialized knowledge and human errors are very common. Kubernetes default values are the main culprit here. For example, allowing anonymous users to pass authentication and authorization is a mistake to avoid.
Secrets Management: Kubernetes does’t use encryption by default, only base64 encoding. Third-party secret providers are the de-facto standard to decouple secrets management and risks from the cluster. ETCD’s encryption at rest isn’t enabled by default either.
Weak RBAC: If Admission controllers and Policies are not properly set up, you will miss that granularity that is important to control request-response cycles.
Supply Chain Vulnerabilities Unawareness: Containers run software inside nodes. Images of these containers are pulled from registries that either live inside the cluster or somewhere else. What we don’t know about this “somewhere else” is a potentially dangerous input in our system. Likewise, egress or whatever output goes outside is equally important, especially to eliminate the risk of data exfiltration.
At a Glance:
If you take a reactive stance on security, or have limited resources to support security processes in your organization, install a security forensic tool, such as kubesec or Falco. The Center for Internet Security (CIS) and Kubernetes Benchmarks provide a rich set of security datasets and best practices for Kubernetes environments.
Alternatively, if your security posture is more proactive and you design policies that support your security processes, the Open Policy Agent(OPA) is an additional open-source tool for policy-engine security enforcements. OPA requires more involvement and learning efforts, but the advantages of using it play in your favor when it comes to having more granular control on your resources.
The key concept here is that each Kubernetes Security Architecture layer should include both redundant security measures and defense-in-depth strategies.
Use Redundancy: This involves duplicating security resources to support failover and high availability.
Defense-in-Depth: This approach involves deploying multiple layers of different security measures to enhance system robustness and resilience.
The CNCF Security Model is an extension of the CISA Security Whitepaper and can be represented as a typical DevOps pipeline including four interrelated phases:
There is nothing special about a DevOps pipeline being sketched with black or white colors. The takeaway here is to look at the bigger picture and include forensics and security measures across different phases of your deployments.
At different stages of your security processes, you need to ask yourself: “Where does this input come from?”, “Do we understand where this output goes?”, “What would happen if we do not integrate security scans in our images?”, and so on and so forth.
AI/ML models can learn from extensive datasets of known vulnerabilities to predict and identify potential security issues in code or configuration files. If we feed these models with new knowledge and new security breaches as they happen, we could build the next-generation of security tools with more precision and power than ever before.
Integrating AI/ML tools with DevSecOps processes, we ensure security checks are integrated into every stage of the development lifecycle. This means security is considered right from the planning and design phases and continues through development, testing, deployment, and monitoring.
Automated security tests, such as SAST, DAST, and IAST, can run continuously alongside other tests. And by shifting security practices to the left, vulnerabilities can be identified and fixed earlier in the development process, reducing the cost and effort required to address them later.
What are the Kubernetes security best practices in 2024?
Knowledge: Invest in knowledge. The majority of security breaches, as reported by top Kubernetes security consultants, all converge to misconfigurations. These could be prevented with better knowledge and awareness of the underlying platforms.
Support and Implement DevSecOps: At the core of the DevSecOps, cross-team collaboration and security integrations at each stage of your development processes could be a game changer and it is one of the best practices you could ever implement.
Explore and Experiment with AI/ML Integrations: Automating processes with AI tools to predict, analyze and identify patterns across millions of data points can be a source of competitive advantage for years to come.
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