From consumer-facing applications like Netflix and Spotify to critical enterprise platforms handling HR, finance, and supply chains, containers have quickly become the backbone for modern software solutions.
However, despite mass adoption, container usage also results in development teams overlooking important security measures. In early 2025, attackers published a malicious version of the Kong Ingress Controller to Docker Hub after breaching its supply chain, embedding a cryptominer inside an image thousands of teams rely on.
Many organizations focus primarily on container image scanning, SCA checks, and license management but these steps only address part of the risk. Incidents like the Kong compromise need security strategies that extend well beyond deployment, including end-of-life (EOL) tracking, and automated updates for both dependencies and images.
In this guide, we’ll walk through the best practices for securing containers at every stage of their lifecycle and provide a detailed checklist to summarize it all.
What is Container Security?
Container security is the practice of protecting containerized applications throughout their lifecycle, from development and deployment to runtime. Because containers share the underlying host kernel and are deployed in large clusters, any misconfiguration or vulnerability can quickly become an attack vector.
Comprehensive container security programs involve validating and hardening images, protecting registries and Kubernetes platforms, enforcing least-privilege access, and detecting suspicious behavior in production, and that's just listing a few. It requires a defense-in-depth model integrated throughout the workflow, ensuring compliance and minimizing your attack surface.
Common Challenges When Securing Containers
Traditional container security strategies fail because teams treat scanning as the finish line instead of the baseline, relying on static, one-time assessments rather than continuous validation.
Here’s a few key blind spots teams miss:
- End-of-life (EOL) Base Images: Workloads running on base images that are no longer maintained.
- Outdated Dependencies: Containers running with no automated dependency update mechanisms, quietly accumulate vulnerabilities over time.
- Runtime Drift: Environments are dynamic, configuration changes, temporary patches, and injected sidecars cause running workloads to drift away from the original image.
Core Principles of Container Security
Effectively securing containers needs a DevSecOps approach, where the entire container lifecycle: from build and deployment to runtime and maintenance is considered. Each stage has unique security requirements and needs constant attention to maintain a strong security posture.
This continuous process can be grouped into three key areas:
- Securing the Build Pipeline: Protecting container images and the software supply chain, a best practice recommended by NIST.
- Securing the Configuration and Deployment: Ensuring containers and their orchestrators are configured correctly.
- Securing the Runtime Environment: Monitoring and protecting live containers.
For a concrete deep dive into implementing container security, check out our article on Container Security — The Complete Guide.
Best Practices for Securing the Build Pipeline
Actionable Checklist
1. Use Minimal and Trusted Base Images
Every piece of software in a container image adds to its attack surface. Using a large, general-purpose base image like the full Ubuntu OS brings in countless libraries and binaries that your application likely doesn't need, many of which may have known vulnerabilities.
Best Practices to Adopt:
- Choose Minimal Images: Opt for "distroless" or "alpine" base images. Distroless images contain only your application and its runtime dependencies,while, Alpine Linux offers a much smaller alternative with basic linux functionality.
- Use Trusted Sources: Pull images only from reputable registries like Docker Hub's official images or trusted internal registries. Avoid using public images from unknown publishers, as they could contain malicious code.
- Pin Image Versions: Instead of using the :latest tag, specify an exact version (e.g., node:18.17.1-alpine). This prevents unexpected breaking changes or new vulnerabilities from being introduced into your builds automatically.
- Use Signed Images: Implement image signing processes (e.g., using Sigstore/Cosign) to cryptographically verify the source and integrity of the image you are deploying.
- Track EOL Base Images at Build Time: Automate your CI pipelines to automatically alert you if the base image you are using has reached its End-of-Life (EOL).
2. Scan Images for Vulnerabilities
Container images are composed of layers, including an operating system, system libraries, and application dependencies. A vulnerability in any of these layers can be exploited leading to privilege escalation.
Best Practices to Adopt:
- Integrate Scanning into CI/CD: Automate vulnerability scans every time a new image is built. This ensures that security checks are a standard part of your development workflow.
- Scan for More than Just OS Packages: Effective scanning tools check for vulnerabilities in OS packages (like apt or yum) and application dependencies (like npm, pip, or Maven).
- Block Vulnerable Builds: Configure your CI/CD pipeline to fail the build if high-severity vulnerabilities are discovered. This enforces a baseline security standard before code is even merged.
Curious about container scanning tools? Check out our article on the Top 13 Container Scanning Tools in 2026.
3. Manage Application Dependencies (SCA)
Your own code relies on dozens, if not hundreds, of open-source packages. A single vulnerable dependency can compromise your entire application. Software Composition Analysis (SCA) helps you find and manage these risks.
Best Practices to Adopt:
- SBOM Generation: A Software Bill of Materials (SBOM) is a complete inventory of every component in your software. This is crucial for tracking dependencies and quickly identifying the impact of a newly discovered vulnerability.
- Check for Outdated Licenses: SCA tools can also scan for non-compliant or risky open-source licenses, helping you avoid legal issues.
- Prioritize Fixes: Focus on vulnerabilities that are actually exploitable. Modern tools can analyze whether a vulnerable function is being called in your code, helping you prioritize real threats over theoretical ones.
- Dependency Autoupdate Workflows: Setup automated workflows to detect outdated dependencies and automatically create pull requests (PR) to update them to a secure version.
- EOL Dependency Detection: Just like base images, application libraries have EOL dates. Track dependencies that no longer receive security support.
Track End-of-Life (EOL) Base Images and Runtimes
Many organizations focus heavily on active CVE scanning but overlook the risk that occurs when a distribution (such as Alpine or Debian) or a runtime version (such as Python) reaches end-of-life and stops receiving security patches.
Once this happens, any vulnerability discovered after the EOL date will no longer receive official patches, and continuing to run these images can also put organizations out of compliance with standards like PCI DSS and SOC 2.
Addressing these challenges requires adopting hardened, minimal base images to reduce the attack surface. It also requires tracking EOL status at build time. Platforms like Aikido Security can automatically warn teams when an image in their registry or CI/CD pipeline is approaching or has passed its EOL date, and even provide auto-update mechanisms for both standard and pre-hardened images.
Best Practices for Deployment and Configuration
A secure image can still be compromised if it's deployed with weak configurations. Securing the environment where your containers run is just as important as securing the containers themselves.
Actionable Checklist
1. Enforce the Principle of Least Privilege
Containers should only have the permissions they absolutely need to function. Running containers with excessive privileges is one of the most common and dangerous misconfigurations.
Best Practices to Adopt:
- Don't Run Containers as Root: By default, containers run as the root user. This is a major risk. If an attacker gains control of the container, they have root access. Use the USER instruction in your Dockerfile to specify a non-root user.
- Limit Kernel Capabilities: Docker's default settings grant containers a range of kernel capabilities. Drop all unnecessary capabilities using the --cap-drop=all flag and add back only those that are essential (--cap-add=...).
- Use Read-Only Filesystems: If a container doesn't need to write data to its filesystem, run it in read-only mode (--read-only). This prevents attackers from modifying files or installing malware.
- Implement Security Profiles: Use built-in Linux security modules like seccomp (secure computing) profiles or AppArmor/SELinux to define exactly which system calls a container is allowed to make.
- Avoid Dangerous Host Mounts: Never mount sensitive host paths, especially /var/run/docker.sock, into a container. This file grants near-full control over the Docker daemon and the host system.
2. Secure Your Container Orchestrator
Orchestration platforms add an extra layer of risk, whether you’re self-hosting Kubernetes or Docker Swarm, or using managed services. Managed platforms like Amazon Elastic Kubernetes Service (EKS), Azure Kubernetes Service (AKS and Google Kubernetes Engine (GKE) minimize these risks by following a Shared Responsibility model: they secure the underlying infrastructure and orchestration layer, while users remain responsible for protecting their containers and applications.
Best Practices to Adopt:
- Use Network Policies: In Kubernetes, network policies act as a firewall for pods. By default, all pods can communicate with each other. Use network policies to restrict traffic between pods, allowing only necessary connections.
- Manage Secrets Properly: Never hardcode secrets like API keys, passwords, or certificates in your container images or environment variables. Use your orchestrator's built-in secrets management tools (e.g., Kubernetes Secrets) or a dedicated solution like HashiCorp Vault.
- Enable Role-Based Access Control (RBAC): For Kubernetes, ensure RBAC is enabled to control who can access the Kubernetes API and what permissions they have. Grant permissions based on the principle of least privilege.
- Use Admission Controllers: Use policy enforcement tools like OPA gatekeeper and Kyverno to automatically audit or block deployments that violate your organization's security rules
Looking for a deeper dive on orchestration security? Check out our article on Docker & Kubernetes Container Security Explained.
Using AI to Automatically Fix Vulnerabilities in Containers
Traditional container scanning identifies vulnerabilities using databases like CVE and NVD, but this often results in long lists of alerts that development teams struggle to prioritize.
AI addresses this challenge by adding context to each finding. It evaluates alerts to determine whether the vulnerable function or component, such as an outdated base image, misconfigured Dockerfile instruction, internet exposed container or software package, is actually being used, speeding up issue remediation and improving developer productivity.
Platforms like Aikido Security extend this by offering AI-powered AutoFix features such as one-click fixes, automated PRs, and base image upgrades. For container images that may contain hundreds of CVEs, its AI-assisted reachability analysis engine filters out the noise and highlights vulnerabilities that are genuinely exploitable.
Best Practices For Runtime Security and Monitoring
Once your containers are running, the job isn't over. You need to monitor them for threats and anomalous behavior. According to research from the National Institute of Standards and Technology, runtime monitoring is a key component of effective container security strategies.
Actionable Checklist:
- Track Network Activity: Monitor network connections to and from your containers. Look for connections to suspicious IP addresses or unusual data transfer patterns.
- Real-Time Anomaly Detection: Employ tools such as Falco and eBPF-based systems to monitor syscalls and identify suspicious container behavior.
- Automate Compliance Monitoring Against Benchmarks: Continuously check the runtime environment against industry best practices like the CIS Kubernetes Benchmarks to ensure configuration hygiene.
- Preventing Container Breakout: Enforce strict isolation using built-in linux security modules such as seccomp (secure computing) profiles and AppArmor to limit a container's access to the host kernel.
- Runtime Drift Detection: Unauthorized changes to running containers compared to their original base image or configuration, indicate potential compromise or misconfiguration.
- Regularly Scan Running Containers for New Vulnerabilities: The vulnerability landscape changes daily; ensure your running workloads are continuously scanned and assessed for new CVEs.
- Log everything: Ensure all events and activities are captured. Establish robust logging and alerting pipelines to aggregate logs into a central system.
A Practical Container Security Checklist
Here is a simple checklist to help you implement these container security best practices.
Conclusion
With all this said, it’s important to remember that code security isn’t a checkbox. It’s not something you set and forget ,it’s an ongoing practice. New threats emerge, new packages appear, and new risks surface every day. The industry has shifted from reactive scanning to proactive, continuous protection, and modern teams are adapting right along with it.
Aikido Security makes this easier by combining AI-powered Static Application Security Testing (SAST), one-click AutoFixes, and pre-hardened Root.io images, helping teams shift left without turning security into a bottleneck.
Want full visibility across container security posture? Start your free trial or book a demo with Aikido Security today.
FAQ
What are the best practices for scanning container images for vulnerabilities?
Image scanning works best when performed at multiple stages, including during builds, before deployment, and within registries. Scans should cover both OS packages and application dependencies, verify image signatures, and leverage hardened base images. Platforms like Aikido Security centralize image and dependency scanning for easier management.
How can I implement role-based access control (RBAC) for container security?
RBAC allows organizations to control permissions by assigning specific roles to users or service accounts. In Kubernetes, this involves creating Roles and ClusterRoles and binding them with RoleBindings or ClusterRoleBindings. Limiting permissions to only what’s necessary.. Tools like Aikido Security provide visibility into RBAC configurations and highlight overly permissive settings.
How do network policies enhance container security in Kubernetes?
Network policies define how pods and services communicate, allowing you to control traffic flow and reduce the potential for lateral movement after a compromise. By default, Kubernetes allows all traffic, so setting deny-by-default policies and specifying allowed ingress and egress rules is critical. Platforms like Aikido Security help teams implement proper network segmentation by flag missing or overly permissive policies.
Which tools are recommended for implementing container security best practices?
Securing containers usually requires multiple tools working together. image scanners for vulnerabilities, secret scanners for sensitive credentials, policy enforcement engines like OPA or Gatekeeper ensure compliance, runtime security tools to watch for suspicious activity, and CSPM solutions to verify cloud settings. Platforms like Aikido Security simplifies processes, enabling automated checks, alerts, and updates across your container ecosystem.
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