Kubernetes Security Audit: Core Concepts & Remediation

Learn all about Kubernetes security audits with our detailed guide. In this blog, learn how to conduct a Kubernetes security audit, post-audit actions, and best practices for cluster security.
By SentinelOne September 15, 2024

Kubernetes (aka K8s) is an open-source system that provides a high level of flexibility and automation, as well as load-balancing. It is a platform that was made to deploy, scale, and manage containerized applications. It is one of the fastest-developing open-source systems providing its users multiple advantages. However, being the system that provides so many benefits to its users, Kubernetes also offers several risks and vulnerabilities. Kubernetes security audit is used to reveal the possible vulnerabilities in your configuration, network policies, and setup. The purpose of this blog is to help you understand the whole K8 security audit process and how it should be done.

What is Kubernetes Security Audit?

Kubernetes Security Audit is a process to inspect how securely the K8s cluster is configured. It helps to outline all possible threats and vulnerabilities that the cluster setting might have. It identifies all existing misconfigurations and assesses compliance with industry standards and organizational regulations.

In other words, the audit focuses on almost every aspect of how a K8s system is designed. Cluster configuration includes the assessment of the configuration of control plane components, nodes, and networking. Therefore, it covers the configuration of the API server, kubelet, and kube-proxy, together with all applied networking and DNS settings. As to access control, the audit involves endpoint authentication, authorization policy, and RBAC.

Network policy audit includes the assessment of network policy configurations, inbound and outbound rules for ingress and egress, and the configuration of pod-to-pod communication rules. Workload security is measured by the assessment of the security context for pods, runtime options for containers, and image vulnerabilities.

Why Do We Need Kubernetes Security Audit?

Kubernetes security audit is a necessity for any organization. It helps businesses with some crucial aspects.

Risk Identification and Mitigation

Kubernetes environments are extremely complex. They consist of a large number of components and configurations. Consequently, these configurations can lead to a great number of vulnerabilities that can be used against the system. A K8s security audit helps to identify and estimate potential risks in the Kubernetes environment.

Compliance Adherence

Most industries have strict requirements for protecting and securing data. For instance, healthcare organizations are required to comply with HIPAA and payment card data organizations must adhere to PCI DSS. Kubernetes security audits help ensure that these compliance standards are met.

Continuous Improvement and Incident Prevention

The probability of incidents and attacks lowers when you can prevent the exposure of the vulnerabilities. No matter how complex and sophisticated applications may become, security audits can prevent incidents by identifying flawed implementations/misconfigurations of security practices.

Third-Party Validation and Trust-Building

Some industries require organizations to confirm their security measures. For example, widespread cloud-native adoption creates the need to confirm the security of clients’ applications in your Kubernetes environment.

Core Security Concepts and Architecture of K8s

Let’s discuss the key components and concepts of Kubernetes for conducting effective security audits.

  • The Control Plane and Node Components

The Kubernetes architecture is divided into two main parts, which are the control plane and worker nodes. Both have specific components, each of which plays a critical role in the operation and security of the cluster.

Control plane components include kube-Episerver, which is essentially the front-end of the Kubernetes control plane and manages and validates all API requests. Another one is etched, a distributed key-value store for all cluster data storage.

The Kube scheduler is responsible for scheduling newly created pods to nodes. Kube-controller-manager runs controller processes to ensure the actual state of the system matches the desired one. Finally, the cloud controller manager is responsible for integrating with underlying cloud providers.

On the worker nodes, we have kubelet, an agent running on the node and ensuring the running of the containers in a pod. Kube-proxy is responsible for maintaining network rules on nodes and allows for pod-to-pod communication. Finally, container runtime is the software used for running containers like Docker.

  • Key Kubernetes Objects (pods, deployments, services)

Different objects are used to represent the state of the cluster and the security implications associated with them. Pods, the smallest deployable unit, need appropriate security contexts and isolation. Managing the deployment and scaling of the pods requires controlled access to their variants and secure updating strategies. Services that allow access to the applications running on the pods need to have well-configured security policies and controlled external access.

Namespaces provide encapsulation of the use of resources, which is vital for multi-tenancy security. Secrets allow for the storage of sensitive information in the cluster. Their usage must be carefully managed, encrypted, and regularly rotated (which can be achieved by using KMS) to maintain security.

  • Authentication, Authorization, and RBAC

Kubernetes offers support for controlling access to the cluster. Authentication is used to verify the identity of users or processes trying to interact with the cluster. This is done with the help of client certificates, bearer tokens, and external authentication providers. Authorization is used to determine what actions authenticated users are allowed to perform within the cluster.

RBAC is the most common type of authorization technique. It allows defining which operations users or service accounts can perform on cluster resources. It is important that both authentication and authorization are set properly because if objects are incorrectly configured, all algorithms used to secure the cluster become useless.

Also, regular auditing of RBAC policies helps to ensure that no users or service accounts are overprivileged, leading to reduced risks of unauthorized access or privilege escalation between software processes.

  • Network Policies and Pod Security

Network Policies and Pod Security Policies are important types of security standards within Kubernetes. Network Policies define in a Kubernetes cluster what constitutes traffic flow to pods that belong to different groups and what is allowed and disallowed. They essentially work similarly to a firewall and control the flows of ingress and egress traffic as executed within the cluster.

Pod Security is a feature that ensures that pods run smoothly and securely. They include multiple APIs that can be used to adjust what each pod is allowed to run on. Currently, the best approach is to use Pod Security Admission (PSA).

Preparing for a Kubernetes Security Audit

Planning and executing a Kubernetes security audit is a critical process that should be carefully prepared and executed in a systematic way. A well-structured audit helps identify potential vulnerabilities, assess risks, and ensure compliance with security best practices. This section outlines the key steps to effectively plan and conduct a comprehensive Kubernetes security audit.

1. Define Audit Scope and Objectives

To start with the security audit, the scope and objectives need to be defined first. The objectives may consist of identifying misconfigurations, checking compliance with relevant standards and regulations, or assessing the efficiency of the measures that are already in place. It is important to include the key stakeholders, such as the DevOps and security teams, as well as the management at this stage to make sure the goals align with the overall organization objectives and risk level. A clearly defined scope and objectives lay the ground for the whole audit process.

2. Gather Necessary Documentation and Access

The next step after determining the scope and objectives of the security audit is to gather all the necessary documentation and ensure relevant access to the Kubernetes environment. The documents that have to be provided are cluster configuration, network diagram, security policy, and any compliance requirements.

Access to the K8s environment has to be provided to the auditors/testers so that they can test the cluster settings and RBAC policies and look into logs for any sensitive information. The access should be read-only so as to not impact the production environments. The documentation also has to provide information on the K8s version and its custom configurations. The documents should also provide information about the underlying infrastructure.

3. Select Appropriate Tools and Methodologies

Choosing relevant tools and methodologies is important for conducting a Kubernetes security audit. There are many open-source and commercial tools available to assist in the audit process, each with specific advantages and focus points.

The choice of tools and methods should be based on the audit scope and objectives and the specific organization’s Kubernetes setup. Also, it is often beneficial to use a combination of tools and methods to take a full view of the cluster’s security posture.

How to Conduct the Kubernetes Security Audit?

The below steps should be followed to complete a K8 Security Audit with ease.

  1. Initial Assessment: Start with a comprehensive look at the documentation, security practices in place, and any issues that have already been uncovered with the cluster being secure.
  2. Cluster Configuration Review: This step reviews the setup of the control plane components, the security settings or profiles of the node configurations, RBAC policies, network policies, pod security policies, or admission controllers in use.
  3. Automated Scanning: Tools to run as part of this step include kube-bench scans for CIS benchmark conformance, vulnerability scanners for both container images and the various Kubernetes components, and network policy field analyzers.
  4. Manual Security Checks: Perform targeted manual inspections of critical configurations and custom scripts.
  5. Access Control and Network Security Assessment: Look at the audit log of the permissions of users and service accounts in use in the cluster, as well as the authentication methods used by those service accounts. On the network side, check how effectively the network policies in use are blocking traffic they should not permit.
  6. Workload and Data Security Evaluation: Check the images used to run containers, pod security contexts, resource limits in place, and the handling of sensitive information. Ensure that data is encrypted both at rest and during transit.
  7. Logging, Monitoring, and Compliance Verification: Look at the standard monitoring, logging, and alerting setup. Check alerts, Slack channels, and aggregated logs in a central location. Where relevant, review the cluster’s compliance with industry standards or best practices or with specific regulations.

Post-Audit Actions and Remediation

Once the K8 security audit is done, we need to take some steps to post it, which include acting on the findings and implementing necessary improvements. In this section, we will cover all these steps:

How to Document Findings and Prioritize Risks

After a Kubernetes security audit has been conducted, all findings need to be properly documented, and risks associated with them should be prioritized in order to execute necessary improvements. A detailed and clear report has to cover all identified vulnerabilities, misconfigurations, and potential threats and should include all technical details and their impact.

To evaluate risks, they need to be scored with an integrated risk scoring system considering such factors as likelihood, potential impact, and possible exploitation. In order to balance the severity of each risk and the required effort and resources, findings should be grouped, and a prioritization matrix should be created. As a result of this step, the findings can be converted into a list of actionable improvements.

Steps for Remediation of Identified Vulnerabilities

Once risks are documented and prioritized, develop a detailed remediation plan outlining specific steps to address each vulnerability. Begin with high-impact, low-effort fixes to demonstrate immediate progress, then systematically address vulnerabilities, starting with the highest-priority issues. This might involve patching and updating components, refining RBAC policies, implementing network policies, enhancing secrets management, and strengthening authentication mechanisms.

Thoroughly test each remediation in a staging environment before applying it to production, and conduct targeted scans to verify that vulnerabilities have been successfully addressed.

Importance of Continuous Monitoring and Improvement

It should always be kept in mind that Kubernetes security is an ongoing process. Strong monitoring solutions should be implemented to detect security anomalies in real-time and be able to alert deviations covered in common use cases. Regular security assessment routines should be scheduled, as well as security scanning of apps and the CI/CD pipeline. Always keep an eye on current Kubernetes vulnerabilities and newly emerged threats, and update your incident response plan from time to time.

Make sure to establish a feedback loop within your team to collect and utilize knowledge about Kubernetes security risks and pay enough attention to learning and training.

Kubernetes Security Audit Best Practices

Some of the best practices that should be followed for efficient audit are as follows:

1. Use Namespaces to Isolate Resources and Enforce Boundaries

Namespaces provide logical separation of resources within a Kubernetes cluster. Properly configured namespaces can isolate the workloads, limit the blast radius of potential breaches by an attacker, and simplify access control. Regularly audit namespace configurations and the allocations of important resources to ensure the proper isolation.

2. Encrypt etcd Data at Rest and in Transit

etcd is a consistent and highly available key-value store used as Kubernetes’ backing store for all cluster data. Because etcd stores crucial cluster data, including secrets and access tokens, it is a highly attractive target for an attacker. Implement encryption at rest for etcd to protect the data against unauthorized access. Ensure all communication with etcd is encrypted in transit using the TLS to prevent eavesdropping or man-in-the-middle attacks.

3. Implement Network Policies for Pod-To-Pod Communication

Use network policies that act as a firewall for the pod-to-pod communication within the cluster. Regularly audit and update the network policies to ensure only necessary traffic between pods is allowed using the principle of least privilege. This limits the potential breach and lateral movement after an attack.

4. Use Admission Controllers to Enforce Security Policies

Admission controllers intercept a request to a Kubernetes API server before an object is persisted. Implement custom admission controllers following the best practices and regularly audit their configuration to enforce the security policies, for instance, by rejecting the creation of privileged containers or accepting only the images from the approved registries.

5. Implement Runtime Security With Tools like Falco or Seccomp

Audit the configuration and allocation of resources for runtime security tools for containers. Those tools detect potential security breaches during container runtime using system calls or by analyzing the container’s behavior.

How can SentinelOne help?

SentinelOne offers robust security solutions that can enhance Kubernetes environments:

  1. Real-time Container and Kubernetes Protection: Containerized workloads and Kubernetes infrastructure are fully visible and protected.
  2. AI-Powered Threat Detection and Response: Possible threats are automatically identified and removed with the help of artificial intelligence.
  3. Runtime Security: SentinelOne offers runtime security, which helps protect containers at execution time and block any threat activity.
  4. Compliance and Audit Support: SentinelOne helps maintain compliance by providing specific data from all the present logs of all Kubernetes activities.
  5. Seamless Integration: The software helps manage security across multiple clusters by directly integrating into the CI/CD pipelines.

Conclusion

In this blog, we understand the importance of Kubernetes security audits in the process of maintaining secure containerized environments. The audit practice is used to determine and resolve vulnerabilities existing in the Kubernetes architecture, which may occur in the control pane, RBAC, workloads, and network policies. Best practices should be followed to avoid any major risks during deployment, and it needs to be a continuous process rather than a one-time thing.

With the growing use of Kubernetes in modern infrastructures, the practice of well-versed and timely audits becomes more critical. Based on the present guide, organizations will be capable of substantially minimizing the risks and protecting the applications and data in containers.

FAQs

1. What is auditing in Kubernetes?

Auditing in Kubernetes refers to the process of capturing and analyzing API requests to the cluster. The audit provides a comprehensive look at all activities on the cluster, including who made which requests, when they made them, and what requests were made. These logs are typically used for security monitoring, verifying compliance, and debugging purposes.

2. How do I monitor Kubernetes security?

To monitor your K8s cluster security, you should enable and configure audit logging, set up real-time monitoring, enforce network policy monitoring, run regular vulnerability scanning, and set up alerts for suspicious activity. For a more comprehensive monitoring of your cluster security, consider using special Kubernetes security platforms.

3. How to enable Kubernetes auditing?

To enable Kubernetes auditing, you need to configure the API server with an audit policy file and specify the audit log path using the –audit-log-path parameter. You can also set up log rotation by defining –audit-log-manage, –audit-log-max size, and –audit-log-maxbackup parameters. Alternatively, you can configure the webhook backend for external logging if you are storing audit data with an external system. After you make all the settings, reload the API server to apply the configuration and start capturing auditing data.

4. How do I check my Kubernetes audit log?

To check the Kubernetes audit log, you can view the audit.log file, which is usually located at /var/log/kubernetes/audit.log, with tools like cat, grep, or tail. For a more advanced logging system, you can use the ELK stack integrated with Kubernetes.

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