Kubernetes Runtime Security

Over the last decade, containerized workloads and Kubernetes (K8s) have taken the software world by storm. Unfortunately, as Kubernetes becomes a staple of enterprise architecture, it becomes a high-value target for threat actors.

Container security in general, and Kubernetes security in particular, is a fundamental aspect of enterprise security posture today. This article will explore Kubernetes runtime security, one of the most critical aspects of K8s security, including seven essential K8s runtime security best practices.

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What is Kubernetes Runtime Security?

Kubernetes runtime security is the set of tools, practices, and technologies that protect running container workloads on Kubernetes.

In other words, Kubernetes runtime security is a subcategory of workload protection and container security. Kubernetes runtime security deals with security from container instantiation to termination. That means runtime security includes things like whether or not containers run as root (they should not!), but does not cover topics like container image scanning.

Kubernetes Runtime Security Challenges and Risks

Because there are so many types of applications running on K8s today, there’s no one-size-fits-all set of runtime security risks for containers or Kubernetes. However, there is a set of Kubernetes runtime security challenges common to most enterprises.

Here are four common security risks related to runtime container security on Kubernetes:

Misconfigurations and insecure configurations: Over 900,000 Kubernetes clusters were found exposed online in 2022. This is a great example of just how widespread the problem of insecure configurations is with K8s.

Privilege escalations: A threat actor gaining access to a K8s environment and escalating to a higher privileged user (e.g., root) is a textbook Kubernetes runtime security threat.

Malware: Malware in container images is a serious problem. In 2022, over 1,600 containers available on Docker Hub included malware like cryptominers and DNS hijackers. Instantiating one of these containers in an environment can instantly introduce threats behind the network perimeter.

Vulnerabilities in K8s and containers: Even when containers aren’t malicious per se, they are often vulnerable to CVEs with known exploits.

Native Kubernetes Runtime Security Tools

Kubernetes offers a limited set of native tools and controls that can limit runtime risk. These include:

Secrets: K8s Secrets are data objects that store information such as an API key or password. Using Secrets helps enterprises to keep sensitive data out of images and Pod specifications.

Admission controllers: With a K8s admission controller, enterprises can limit modification (but not reading) of Kubernetes API endpoints.

Network policies: Kubernetes network policies are similar to traditional ALLOW and BLOCK firewall rules that enforce policies at the network and transport layers.

Audit logs: Audit logs provide details on actions that have occurred in a cluster. For example, API activity can be audited. These logs can allow analysis and detection of malicious behavior.
RBAC: Role based access control (RBAC) allows administrators to limit K8s API access based on an entity’s role.

Because native Kubernetes runtime security tools don’t directly address use cases like real-time threat detection, many enterprises depend on more robust workload protection tooling.

7 Kubernetes Runtime Security Best Practices

These six Kubernetes runtime best practices can help enterprises limit many K8s security threats.

Don’t run containers as root: Running containers as root sets up threat actors for privilege escalation attacks. Simply not running as root can mitigate many threats.
Audit and automate container configurations: Publicly exposing data that should be in Secrets or making database instances internet-facing are examples of misconfigurations that can lead to a breach. Auditing configurations and automating config deployments using Infrastructure as Code (IaC) is a great way to limit risk.
Lock down the network layer: In addition to K8s network policies and RBAC, network security tools like IPS/IDS and NGFW can detect and prevent threats before they reach workloads. Additionally, enterprises should avoid exposing the Docker daemon socket whenever possible.
Avoid privileged mode: Just like not running containers as root, enterprises should avoid running containers with the –privileged flag. The –privileged flag allows containers to bypass various checks that keep a system secure.
Use read-only filesystems whenever possible: Read-only filesystems prevent threat actors from writing malware directly to a container’s filesystem. This can limit a threat actor’s ability to perform an exploit.
Only run trusted container images: Public repositories can threaten security in container runtime environments as soon as an administrator instantiates a compromised image. Only using trusted container images can help enterprises limit the risk of images from public image repositories.
Secure the kernel level: Solutions like SELinux, cgroups, and AppArmor can add a layer of protection to Kubernetes runtime security. For example, AppArmor can define policies that restrict access to a variety of kernel resources to reduce the risk of apps leveraging a system capability they shouldn’t be able to access.

Shifting Left Complements Effective Kubernetes Runtime Security

Of course, no aspect of security exists in a vacuum. Runtime security is important, but security starts well before a container is instantiated. Some of the aforementioned Kubernetes runtime security best practices make that clear, and the concept of shift-left security drives the point home. Integrating security early in the development lifecycle and following through with robust runtime protection provide the best of both worlds.

Kubernetes Runtime Security with CloudGuard Workload Protection

CloudGuard Workload Protection is a platform that provides the end-to-end protection with centralized management that enterprises need for Kubernetes containers and serverless functions.

Benefits of CloudGuard Workload Protection include:

Zero trust security across apps: Protection for Kubernetes containers, APIs, and serverless functions.

Auto-deployment of security configurations: Define and deploy security policies automatically to reduce the risk of human error and misconfiguration.

Multi-cloud and hybrid cloud support: Ensure security across clouds and on-prem.

Container image scanning: Detects vulnerable or malicious containers before they’re instantiated.

Real-time incident detection: Intelligent detection of malicious behavior can stop threats before they do damage.
Behavioral defense for serverless functions: Serverless security requires context, and behavioral defense can intelligently detect malicious use of serverless functions.

To learn more about CloudGuard Workload Protection, sign up for a container security demo today. In the demo, you’ll learn about key container security concepts such as IaC scanning, automated runtime protection, and security across all clouds.