Top 8 Container Security Best Practices

Containers are a streamlined way to build, test, and deploy applications on local machines and in the cloud. However, there are some security challenges that are unique to containers. A large attack surface, access control issues, and vulnerable images can pose substantial risk. However, it is possible to prevent an exploitation of these vulnerabilities, by implementing container security tools and practices. 

What Are Containers?

Containers are an executable unit of software that packages application code, together with its dependencies, and libraries. You can run containers in any environment, including on-prem desktops and cloud ecosystems.

To do this, containers leverage a type of Operating System (OS) virtualization. OS virtualization isolates processes and controls the amount of memory, CPU, and disks used in those processes. For example, in Linux, containers isolate namespaces and cgroups primitives. 

Containers are faster and smaller in size, compared to a virtual machine. Containers do not need to include a guest OS in every instance, instead, they take advantage of the resources and features of the host OS.

Container Security Flaws

Top container security flaws include malicious code in container images, large attack surface, user access control issues. 

Container images

A container image is an immutable, static file that includes executable code. Container images enable developers to create their own isolated process or download public files from the Docker Hub. However, images can be vulnerable to security threats. 

Vulnerable images are images that originate from an untrusted registry. These images can include malicious code if not properly tested. Container images often include open source components that weren’t scanned and tested for vulnerabilities. Incorporating these images into the build can present a greater risk of open source vulnerabilities.

Attack surface

An attack surface is the total amount of vulnerabilities that any attacker can exploit. Reduction of the attack surface ensures that vulnerable code does not make its way into the environment. Containers, however, have some operational and specialized elements that require additional attention. Ensuring a minimal attack surface in containers requires a secure host, and consistent maintenance of container configurations and profiles.

8 Docker Container Security Best Practices

The following best practices can help you create a tight Docker container security infrastructure.

  1. Docker runtime security

A container runtime is software that executes containers and manages container images. Editing the container image and then deploying a new container is the main way to make changes to a container runtime. Creating a runtime security policy can help define proper response actions during runtime. The security policy should send alerts and create remedies in case of a suspicious behavior.

  1. Docker image authenticity

Many systems are based on container images. Therefore, vulnerabilities in images can cause damage across an entire organization. To ensure your images are protected, scan all open source and third-party containers, and create a registry of trusted images. In addition, update your security measures frequently, and keep your systems as simple as possible. 

  1. Use Docker secrets to manage sensitive data 

Secrets are volumes of sensitive data, such as SSL certificates, SSH private keys, and passwords. To ensure the security of sensitive information, you can use orchestration platforms like Docker Swarm or Kubernetes to deploy Docker secrets during runtime.

Docker swarm encrypts secrets during transit and at rest. You can access a specific secret only if you have permission. Secrets are automatically created in Kubernetes, along with the required credentials for accessing the API. You can automatically adjust your pod to use this secret. 

  1. Limiting resources

Running as many containers as needed provides you with a lot of flexibility in production. However, this also creates many risks in case containers are compromised. Therefore, you have to monitor the activity of a container, and limit use of resources. Software bugs, design errors, or malware attacks can lead to Denial of Service (DoS). Limiting the amount of system resources for each container, can help you handle the large attack surface.

  1. Using a SECCOMP profile to limit system call

Secure Computing Mode (SECCOMP) is an open source Linux kernel mechanism used for Mandatory Access Control (MAC), and runtime protection. SECCOMP can block multiple system calls in Docker containers, and create a whitelist of additional types of calls you can block. You can use a SECCOMP profile to block some attacks and prevent attacks from spreading to the rest of the infrastructure.

  1. Access management

Access management solutions help reduce security risks in Docker by enabling granular Role Based Access Control (RBAC) management. Role based access management solutions, such as Active Directory, enable you to manage access to containers across teams and development stages. In addition, you can run containers with minimal privileges.

  1. Complete lifecycle management

Lifecycle management tools can help you manage, monitor, and analyze every element of the container infrastructure. For example, you can prevent deployment of vulnerable containers by scanning for vulnerabilities during the delivery lifecycle. Management of the entire lifecycle ensures the security of containers throughout all phases of development and deployment.

  1. Container monitoring

You can monitor containers using tools like Datadog, Prometheus, and Scout. Monitoring container systems can help you detect potential attacks, send alerts, and even automatically fix problems. Make sure to analyze container log data periodically, and use this data to create preventive actions.


Containers help businesses to run reliably, efficiently, and with agility. However, securing containers requires a bit of work. Implementing monitoring, access management, sensitive data security, and image authentication can help you get the same level of security in containers as the rest of your business.



Author Bio: Kobi Bohbot

Image Source

Kobi is a software developer who helps entrepreneurs translate ideas into working products. You can find his tutorials and insights at



Leave a Reply

Fill in your details below or click an icon to log in: Logo

You are commenting using your account. Log Out /  Change )

Google photo

You are commenting using your Google account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s

This site uses Akismet to reduce spam. Learn how your comment data is processed.