Your container might look rock solid, but is it really? Containers offer fantastic flexibility for deploying apps. Yet, their ability to spin up and down on demand makes them prone to runtime threats. Privilege escalations, container escapes, and compromised network setups are just some of the vulnerabilities that can creep into your environment and often even slip past security measures.  

Surprisingly, 91% of runtime scans fail to detect these critical vulnerabilities. Furthermore, only 2% of granted permissions are being used in container environments, meaning many accounts are overprivileged for no reason. Relying on occasional security scans isn't enough---your containers need a robust, continuous security plan to prevent and combat threats effectively.

What is Container Security?

Container security is a layered defense approach that combines various practices and technologies to shield containerized applications from threats. Containers bundle an application and all its dependencies into a self-contained unit and are a pillar of modern microservices and cloud-native deployments. However, the mobility and flexibility that make them useful also introduce unique security challenges that demand a holistic and proactive strategy. 

Critical Components of Container Security 

• Container image security is the first line of defense. A compromised image can be a vehicle for vulnerabilities and malicious code, impacting all containers built from it. Each image must undergo rigorous vulnerability scanning using tools to analyze each layer for known risks and configuration issues.

• Registry security involves protecting container registries, where images are stored and managed. Secure registry configurations can help prevent the insertion of malicious images that could compromise an application's integrity. 
• Orchestrator security pertains to securing container orchestration platforms, such as Kubernetes orchestration. Platforms like Kubernetes manage the deployment, scaling, and operation of containerized applications across clusters of hosts. Their complex functionality and critical role in managing resources introduce major security concerns.
• Container engine security focuses on the underlying runtime system that manages and executes containers, such as Docker, containerd, or CRI-O. These container engines are responsible for interfacing with the operating system kernel to provide the isolated environments that containers run within. 

The Shared Responsibility Model in Container Security

The shared responsibility model divides tasks between cloud service providers and users in container security. This approach is vital because it specifies what each party must secure. For example, cloud providers like AWS, Azure, and Google Cloud handle the security of foundational infrastructure, such as physical servers, storage, and networking. Meanwhile, organizations are responsible for securing their applications, data, and container configurations.

While the cloud provider manages the infrastructure's security, you must actively secure your containers by managing access controls, hardening images, and continuously monitoring for vulnerabilities. Ignoring these responsibilities can leave your applications vulnerable to threats, even if the underlying infrastructure is protected.

Misconfigurations are particularly troublesome, as containers with excessive privileges or default security settings can expose the host system to significant risks. Since containers share the host's kernel, a breach in one can compromise others on the same host, amplifying the attack's impact. 

An old container image with unpatched vulnerabilities can provide a gateway for unauthorized access, malicious code execution, or lateral movement within the network.

7 Best Practices for Container Security

1. Image Hardening Techniques

Image hardening actively reduces the attack surface of container images by rooting out vulnerabilities and stripping away unnecessary components. Always use minimal base images---such as Alpine Linux---which have fewer components and thus a smaller attack surface, and regularly scan these images for vulnerabilities using tools like Trivy. 

2. Container Image Provenance

Upholding the integrity and authenticity of container images is critical to preventing the deployment of malicious or tampered images in your environment. Integrate image signing into your CI/CD pipeline so that any image lacking a valid signature is automatically rejected. 

Use Docker Content Trust (DCT) for image signing and verification, guaranteeing that only trusted and verified images are pulled and run. Tools like the Notary repository enable you to cryptographically sign your images, establishing a secure chain of custody from the source to deployment.

3. Limit Privileges

Avoid running containers with root privileges -- instead, use user-specific IDs with only the required permissions. Kubernetes' Role-Based Access Control (RBAC) offers fine-grained permission management, enabling you to set up roles and bindings to limit user and service access to the minimum required resources. These strict controls help reduce the potential impact of a security breach.

Consider using Pod Security Standards and the Pod Security Admission Controller to enforce security standards across your cluster. These mechanisms can restrict the use of privileged containers, limit the capabilities available to containers, and define security contexts. Pod Security Standards define three levels of security (Privileged, Baseline, and Restricted), while the Pod Security Admission Controller enforces these standards at the namespace level.

4. Secrets Management

API keys and passwords should never be embedded directly in container images. Instead, use secret management tools like HashiCorp Vault or Kubernetes Secrets to handle and store this data securely. These tools allow you to dynamically inject secrets into your containers at runtime without exposing them in your images or codebases.

5. Network Segmentation

To isolate services and control data flow, implement network policies that restrict traffic between containers, allowing only the necessary communications. Tools like Project Calico define and enforce these policies within Kubernetes, effectively isolating workloads.

To get more granular, you can set up Kubernetes Network Policies to define each pod's specific ingress and egress rules. This setup allows you to control which pods can communicate with each other and restrict external access to only trusted sources.

For more advanced network security and observability, consider implementing a service mesh like Istio or Linkerd.

6. IaC Template Scanning

Perform regular scans on your Infrastructure as Code (IaC) templates to catch security issues before they become problematic. KICS, available through the Jit platform, can be used for IaC security scanning across a wide range of formats, including Terraform, Cloudformation, and AWS CDK, for potential misconfigurations, such as hard-coded secrets, open security groups, and excessive permissions that may compromise your infrastructure.

Configure your IaC tools to align with compliance frameworks such as NIST or CIS benchmarks to enhance these scans. For example, you can set up Terrascan to enforce compliance checks against these standards, ensuring that templates meet industry best practices and regulatory requirements.

7. Automate Scanning

With automated scanning, you can significantly reduce the exposure window by detecting vulnerabilities early. Jit orchestrates Trivy to enable continuous scanning by embedding vulnerability assessments directly into your CI/CD pipeline. This setup triggers scans automatically on every code commit, build, and deployment, ensuring timely detection of security issues throughout the container lifecycle.

Use automated reporting features to generate detailed vulnerability reports, including severity ratings and remediation steps. Integrate these reports with your issue-tracking system to streamline the resolution process. Be sure to implement a process for addressing false positives and continuously tuning your scanning tools to reduce noise and focus on actionable security insights.

Why Container Security Matters

56% of geo-distributed firms have already shifted towards container technologies, and the popularity of containers continues to increase. Their widespreadness makes them an attractive target for attackers. 

As containers bundle applications and their dependencies, they can inherit and propagate security flaws if not managed carefully. Attackers zero in on these environments, taking advantage of vulnerability misconfigurations, outdated software, and weak access controls.