Containers have revolutionized the software development process by enabling the creation, packaging and deployment of applications in a more efficient and scalable way. However, with great power comes great responsibility, and the significant focus on “shift-left security” has created risks for organizations that have neglected security during runtime.

By taking a multi-layered and comprehensive approach to container runtime security, organizations can help mitigate the risks associated with container environments and protect their critical data and applications from potential security threats. With the right security measures and policies in place, container environments can provide the agility and scalability that organizations need without creating vulnerabilities that put the entire architecture at risk.

Kicking the “shift-left” crutch

One common mistake in container security is failing to treat security as a continuous practice. The industry has recognized the importance of the shift-left approach, which prioritizes integrating security into the development and deployment cycle at the outset of a project. However, some enterprises have taken this too far and believe that runtime security is less important if they allocate enough resources to planning and testing. 

This is a misguided approach because, in reality, a breach is a matter of when – not if. The dynamic and distributed nature of container environments can make it difficult to maintain a clear picture of container behavior, making runtime security even more critical. Runtime security tools can help security teams detect anomalous behaviors, such as unexpected network traffic or resource utilization, that might indicate a security breach. They can also help security teams respond to incidents in real time through actions like blocking network traffic to the affected container, quarantining the container, or other methods of preventing the spread of an attack.

Without runtime security, organizations are at risk of potential security breaches going undetected for extended periods of time, allowing attackers to move laterally within the environment and potentially compromising critical data and applications. By implementing runtime security measures, organizations can help reduce the risk of security incidents and minimize the potential impact of any security breaches that do occur.


One of the best practices for securing containers is to use a multi-layered security approach that includes security measures at different levels, such as network, host, and application layers. This approach provides a defense-in-depth strategy that can provide more comprehensive protection against different types of attacks. The goal of the defense-in-depth approach is to make it more difficult for attackers to penetrate an organization's defenses and limit the damage if an attack does occur.

In the context of container environments, a defense-in-depth approach would entail an organization using network security tools like firewalls and intrusion detection systems to monitor and filter traffic to and from containers. They might also implement host-based security controls like secure boot and encryption to protect against attacks targeting the underlying host system. At the application layer, organizations might use container security tools like vulnerability scanners, container image scanners, and runtime security tools to monitor container behavior and detect and respond to potential threats in real time.

Overall, the defense-in-depth approach helps organizations maintain the integrity and availability of their critical data and applications, even in the face of sophisticated cyber threats targeting container environments.

 Real-time protection with runtime policies

Security policies, which define and enforce the security controls that should be in place during runtime, provide powerful methods for securing container environments beyond implementing a multi-layered approach. It's important to regularly review and update security policies to ensure that they remain effective and up-to-date with the latest security threats and best practices. Some examples of security policies that can be used in container environments:

  • Pod Security Policies (PSPs) are used to enforce security controls at the pod level. They can be used to restrict the use of privileged containers, limit host namespaces and ports, and prevent the use of host networking and storage. PSPs enable administrators to define a set of minimum security standards that all pods must adhere to before they can be deployed.
  • Network policies are used to restrict network traffic between pods in a Kubernetes cluster. They enable administrators to define rules that allow or deny traffic between pods based on factors like source and destination IP addresses, ports, and protocols. By using network policies, administrators can enforce network segmentation and isolate sensitive workloads from the rest of the cluster.
  • Resource quotas are used to limit the amount of CPU, memory and other resources that can be used by pods and containers within a cluster. They enable administrators to prevent pods from consuming too many resources and ensure that resource usage is optimized across the cluster. By using resource quotas, administrators can also prevent resource exhaustion attacks, where an attacker attempts to consume all available resources within a cluster.
  • Role-Based Access Control (RBAC) is used to control access to resources within a Kubernetes cluster. It enables administrators to define roles and permissions for different users and groups, allowing them to access only the resources they need. By using RBAC, administrators can prevent unauthorized access to sensitive resources and reduce the risk of a data breach.
  • Image policies are used to control the types of images that can be deployed within a container environment. They enable administrators to define rules that allow or deny the use of certain images based on factors such as the image source, registry and tags. By using image policies, administrators can prevent the deployment of vulnerable images within the container environment.

Results without elevated risk

Securing container environments requires a multi-layered approach that includes security measures at the network, host and application layers, as well as the implementation of security policies during runtime. It's important to use a combination of these measures to ensure that container environments remain secure and resilient against attacks.

Some best practices for securing container environments during runtime include implementing security policies such as resource quotas, RBAC and pod, image and network-focused security policies. In addition, ongoing monitoring and observability are essential for ensuring that container environments remain secure over time.

By following these best practices, organizations can help mitigate the risks associated with container environments and protect their critical data and applications from potential security threats. While container environments present unique security challenges, implementing the right security measures and policies can help organizations reap the benefits of these agile and scalable environments without compromising security.