Kubernetes poses several security challenges unique to this technology, and teams struggle to keep up. Case in point, the notorious malware group TeamTNT is back, this time targeting Kubernetes clusters.
While Kubernetes security requirements grow, standard cloud security approaches fail to provide coverage. But there is a way out.
Read this article to dive into the most pressing Kubernetes security challenges, learn best practices for protecting clusters, and see why automation is key.
How does Kubernetes security differ from traditional cloud security?
Securing Kubernetes clusters is tricky because of how Kubernetes works: the smallest component is built with multiple layers of base OS and other dependencies, while containerized microservices are connected using APIs. As you can expect, each layer or service in a Kubernetes deployment can introduce vulnerabilities.
Some teams use a container-centric approach to Kubernetes security, focusing on protecting container images and the runtime for containers.
Other teams choose Kubernetes-native security solutions, such as Kubernetes Security Posture Management (KSPM) solutions. These solutions use Kubernetes context and built-in controls to apply risk-based security best practices throughout the application development life cycle. Additionally, KSPM guards against risks and weaknesses specific to Kubernetes, such as incorrect RBAC policies, insecure control plane components, and stolen secrets.
Kubernetes and containerization enable faster and more scalable DevOps but also introduce extra security vulnerabilities. Deploying more containers increases your attack surface and complicates the identification of vulnerable or misconfigured containers. When combined with a lack of security awareness and an ever-present skills gap, security events can have disastrous effects on Kubernetes deployments.
Common Kubernetes security challenges and how to solve them
Security visibility
Security visibility in Kubernetes refers to monitoring, detecting, and responding to potential threats across clusters, workloads, and network traffic. Given Kubernetes’ dynamic and distributed nature, achieving comprehensive visibility is crucial for identifying misconfigurations, unauthorized access, and runtime anomalies.
Solution: consolidated security dashboard
A robust KSPM system should feature a dashboard that provides a quick overview of the organization’s current security status. Cast AI’s security dashboard presents a consolidated view of multiple security analyses for all the clusters combined, allowing teams to easily monitor and manage overall security.
Configuration assessment
Human error and the lack of automatic security assessments often lead to misconfigurations, jeopardizing Kubernetes deployments and potentially leading to breaches.
Due to containers’ dynamic nature, discovering misconfigurations and maintaining a consistent security posture can be difficult. Designed for speed and operability, Kubernetes typically has open and unrestricted default setups, leaving organizations vulnerable to attacks.
Solution: automated cluster analysis for misconfigurations
KSPM tools examine the collected data by comparing configurations to security best practices and finding possible security risks and misconfigurations in the Kubernetes infrastructure.
Cast AI’s compliance dashboard provides a comprehensive security overview by automatically comparing cluster configurations against industry standards such as CIS Benchmarks. It identifies misconfigurations, highlights security gaps, and offers actionable recommendations to ensure compliance and reduce risk. With real-time insights and guided remediation, organizations can proactively strengthen their security posture.
Runtime detection and response
The abundance of runtime threat vectors in containerized applications challenges teams that detect and respond to such issues.
A bad actor can get initial access to a Kubernetes environment, execute malicious code, raise privilege, establish persistence, elude detection, and move laterally, resulting in data loss, exfiltration, denial of service, or resource hijacking.
Solution: real-time anomaly detection
When we launched our automated KSPM solution, we didn’t just focus on known threat vectors. Attackers have become highly advanced and aware of how vulnerability scanners and basic network thwarting mechanisms work. Their focus has shifted to social engineering tactics to evade detection, but their operations within underlying containers can escape a security team’s eyes without advanced runtime insights.
Cast AI employs a lightweight eBPF agent that immediately recognizes any suspicious behavior within containers and continuously checks the environment for anomalies. Users can individually enable specific rules based on their applications.
The runtime anomaly detection engine can discover and prevent common crypto miners responsible for most attacks against Kubernetes clusters without requiring network-level analysis or the creation of sophisticated rules.
Shifting security left
The shift-left security concept pushes Kubernetes security efforts to the initial stages of the container life cycle. However, this is difficult because shift-left security requires engineers to become security users, equipped with the knowledge and tools to make security decisions inside their workflows.
However, the commercial benefits of transferring security to the left are enormous. This is the primary approach to Kubernetes and container security. Handling more security vulnerabilities during the development stage reduces the likelihood of runtime issues, leading to shorter project delays.
Solution: speeding up issue resolution with recommendations
Many cloud-native security tools give users a lot of information about the vulnerability but little advice about how to fix it. A good KSPM tool lets users quickly resolve the issue by providing practical recommendations.
Cast AI’s KSPM solution is at the forefront of automating the security process, and one of the simplest methods to eliminate risks is to use our base image recommendations.
Here’s an example of recommendations for base image versions:
Kubernetes infrastructure security
The multiple levels of Kubernetes, from control plane components like the API server, kube-scheduler, kube-controller-manager, etc., to worker node components that run containerized workloads, have their own security problems.
You must properly set up each of these services to provide a secure cluster environment for application execution.
Furthermore, whether you deploy Kubernetes as a self-managed or fully managed cloud service affects how you secure the various Kubernetes components. For example, you’re generally responsible for all control plane and node components in self-managed settings. When using a managed Kubernetes service, the security responsibility is split between the service provider and you, which presents another issue.
Solution: automated node OS updates
Cast AI manages the entire Kubernetes infrastructure, promptly updating nodes with outdated, insecure operating system software. You don’t need to be concerned about a cluster that is not audited for security. This is useful if you are running multiple cloud clusters and want to generate reports for compliance purposes.
10 best practices for Kubernetes security
In addition to the out-of-the-box security controls available from solutions such as Cast AI, here are some best practices to keep your clusters and containers safe from threat actors.
- Don’t keep secrets in an environment variable
Having your objects use a secret in an environment variable is good practice since other parts of your system can access environment variables. To minimize potential attacks, it’s best to use secrets as files or take advantage of a secretKeyRef.
- Use strong Kubernetes authentication and authorization
Integrating Kubernetes with a third-party authentication provider is smart, as it delivers extra security features like multi-factor authentication. To make access to the control plane more secure, avoid managing users at the API server level.
Use an Identity and Access Management (IAM) solution from the cloud service provider if you’re running a managed Kubernetes service like EKS, GKE, AKS, or similar. Go for OpenID Connect (OIDC) alongside an SSO provider you got used to if CSP IAM isn’t an option.
- Disable the NET_RAW capability
If your Kubernetes containers don’t drop the NET_RAW capability, you risk enabling a wide range of networking exploits within the cluster. To ensure you follow best practices, it’s best to use Policy Enforcement solutions like Open Policy Agents, Kyverno, or the Kubernetes Pod Security admission controller.
Use drop for ALL or NET_RAW capabilities in the pod’s securityContext definition to ensure that the NET_RAW capability is disabled.
- Avoid sharing the host’s IPC or network namespace
Check if your pods are sharing the host’s IPC or network namespace. Sharing namespaces for pod and host interprocess communication may open access to shared information. Pods should not be allowed access to the host namespaces.
Sharing pod and host network namespaces enables access to the host network from the pod, which breaks network isolation. That’s why you should set the hostNetwork parameter to false in PodSecurityPolicy.
- Use Kubernetes Role-Based Access Control (RBAC)
RBAC helps define who has access to the Kubernetes API and on what permissions. In Kubernetes 1.6 and higher, RBAC is usually enabled by default. Since Kubernetes combines authorization controllers, make sure to disable the legacy Attribute Based Access Control (ABAC) when enabling RBAC.
Pick namespace-specific permissions over cluster-wide permissions. Even when debugging, don’t grant cluster administrator privileges. If you don’t, it could compromise the security of your container.
- Avoid usage of root file system for container security
Are your containers running without a read-only root file system? Using a read-only file system prevents malicious binaries from writing to a system or a system takeover by attackers. You can ensure containers use only the read-only file system by setting readOnlyRootFilesystem to true in Pod securityContext definition.
- Isolate your Kubernetes nodes
Never expose Kubernetes nodes directly to public networks. Ideally, these nodes are located on a separate network and, if possible,without any direct connections to the general corporate network.
You can achieve this by keeping Kubernetes control and data traffic isolated. Otherwise, they both flow through the same pipe. Open access to the data plane also means access is open to the control plane. Configure nodes with an ingress controller and set it to only allow connections from the master node via the specified port through the network access control list (ACL).
- Avoid running containers in privileged mode
Does your deployment have containers running in privileged (root) mode? This allows the container to gain access to the host’s critical resources. Avoid running containers in privileged mode or enable the podSecurityPolicy with the privileged parameter set to false. This will ensure that containers can’t run processes that require root privileges on the host.
- Check for unsafe /proc mount
Deployments with unsafe /proc mount (procMount=Unmasked) will allow bypassing the container runtime’s default masking behavior. Setting a container with the Unmasked /proc mount type can potentially expose the host information to the container and, as a result, cause a potential information leakage or container escape. Set procMount=Default to ensure the container doesn’t unsafely expose any parts of /proc.
- Have a rolling update strategy
Another smart move is developing a rolling update strategy. Rolling updates allow deployment updates to minimize your application downtime by incrementally updating pod instances with new ones. See this page in the Kubernetes docs for more details.
Stay ahead in your Kubernetes security journey with Cast AI
Following Kubernetes security best practices strengthens workloads, but manual management adds complexity and risk. Automating misconfiguration detection, compliance, and threat response reduces DevOps and DevSecOps toil while ensuring continuous protection. With automated security enforcement, teams can focus on innovation, knowing their Kubernetes environment stays secure at scale.
