The Importance of Container Security
Since containers offer a flexible and portable way to run applications, they have become a popular solution for deploying software. However, containers also introduce new layers into software delivery pipelines and hosting stacks, such as:
- Container image repositories, which host container images (meaning static files that store the executable files for containers) and make them available for download.
- Container runtimes, such as Docker’s, which execute running containers based on images.
- Container orchestration tools, like Kubernetes, which manage containers running on distributed infrastructure.
These components add complexity to software environments and increase their attack surface. Container security is important for ensuring that organizations have the defenses in place to secure these components against risks and threats while also defending other resources – such as the operating systems running on servers that host containers – that exist both in containerized and non-containerized hosting environments.
Container Security Challenges
In addition to the fact that container security requires managing a larger attack surface, container security is challenging because containers restrict the direct visibility that developers, IT engineers and security analysts have into workloads. As a result, detecting and reacting to threats can be more challenging.
For example, if analysts perform security monitoring based only on the metrics and logs that are available from the operating system that hosts containers, they may not detect anomalous activity within a container because metrics and logs produced by containers themselves are typically not managed by the operating system. To gain visibility into what is happening inside each container, engineers need security tools that are capable of breaking through the abstraction layer that separates containers from their host servers.
Components of Container Security
Not all containerized environments include the same types of tools. For example, it’s possible to run containers without using an orchestrator. This means that the components of container security may vary depending on which specific tools and platforms a team uses to manage its containers.
That said, in most cases, container security includes the following key components:
Registry Security
If attackers breach the registry that hosts container images, they could insert malicious code into them, which will in turn spread malware to any environments that run containers based on tainted images.
To protect against this risk, engineers should implement strict access controls that prevent unauthorized access to the contents of container registries. They should also monitor registries for unusual access patterns that could be a sign of malicious activity.
Runtime Security
Attackers can exploit vulnerabilities in container runtimes to take control of containers and possibly even the servers that host them. Organizations can manage this risk by ensuring that they manage Docker container security (or the security of whichever runtime they use) by keeping their container runtime software patched and up-to-date.
Environment Security
The environment configuration that admins apply when they run containers can have security implications. For instance, running containers as root is generally not a best practice because it gives them elevated permissions that increase the potential harm caused by a breach. Securing the settings that apply to the environments that host containers is an essential component of container security.
Orchestration Security
For containerized workloads that use orchestrators, like Kubernetes, it’s crucial to keep the orchestration platform free of known vulnerabilities. In addition, admins should follow best practices when configuring and managing the orchestrator to defend against threats. In Kubernetes container security, for example, admins should use the built-in Role-Based Access Control (RBAC) framework to restrict access to resources.
Storage Security
Stateful containerized applications depend on storage resources. Protecting the data hosted in that storage is another important component of container security.
Network Security
Containers rely on networks to communicate with each other and to accept and receive external requests. Engineers should therefore secure both internal and external networks by ensuring they are properly configured, as well as monitoring them for unusual activity.
Types of Container Security: Docker, Kubernetes, AKS, GKE, EKS
Depending on where containers are hosted, certain additional container security solutions or practices may be available.
For example, teams that use Docker can manage some aspects of Docker container security via the platform’s built-in security scanner to detect malicious dependencies inside container images. On Kubernetes, the native RBAC framework can help protect containerized workloads.
Similarly, when running containers via a managed service such as Azure Kubernetes Service (AKS), Google Kubernetes Engine (GKE) or Elastic Kubernetes Service (EKS), organizations may choose to take advantage of the security tooling that is built into the platforms of each service’s cloud provider to help monitor and protect their workloads.
Container Security Solutions Features
The container security solutions that a team uses to secure containers should provide the following core features:
- Support for securing container image registries against malicious access.
- The ability to scan container images for malicious or vulnerable contents or dependencies.
- Validation of container environment configurations to protect against mistakes or oversights that may increase the risk of a breach.
- Monitoring of running containers, as well as the storage and network resources with which they interact, to detect anomalous activity that may signal an attack.
- Where relevant, scanning and auditing of the container orchestrator to defend against security risks.
Container Security Best Practices
For most containerized workloads, the following best practices can help minimize the risk of attack and maximize a team’s ability to detect it:
Enforce Least Privilege
Admins should follow the principle of least privilege when setting up the components within a containerized hosting stack. Least privilege means restricting permissions to the lowest level necessary.
Rely on Trusted Images
Avoid downloading container images from untrusted registries, which are more likely to contain malware. Where possible, choose registries maintained by well-established, trustworthy organizations.
Monitor All Layers of the Environment
When it comes to container security, scanning and monitoring only some layers of an environment is not enough. Organizations should continuously monitor all components – from container registries and images to runtime environments, to the underlying infrastructure and everything in between. Comprehensive monitoring maximizes admins’ ability to detect risks.
Minimize the Attack Surface
Although the attack surface for containers is inherently larger than for a non-containerized app, teams can reduce their attack surface by being sure to avoid running unnecessary components or layers. For example, containers that developers launch for testing purposes should be shut down as soon as testing is complete.
Use Minimalist Images
The fewer contents that exist inside a container image, the lower the risk of vulnerabilities. For that reason, prefer minimalist images, meaning those that include only the libraries, software packages and other components necessary to run an application.
Container Security with CloudGuard Workload
The key to effective container security is to integrate security into every process and resource that containers depend on. CloudGuard for Workload Protection makes this easy by providing a comprehensive container security solution that provides:
- Integration with the software delivery lifecycle to catch vulnerabilities before they enter container images.
- Continuous container image scanning, ensuring instant detection of vulnerable images.
- Runtime protection to defend against active threats.
- Kubernetes container security to keep the orchestration layer safe.
- Comprehensive monitoring and intrusion detection features based on ongoing analysis of account activity, cluster operations and application traffic flow.
Learn more by reading the Container Security guide, or by requesting a free demo.
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