Cloud Security

Docker Container Security: Easy Guide 101

Containers are globally used for building various projects and are highly convenient as they are fast, flexible, and scalable. Docker’s platform adds portability to cloud workloads, is open-source, and enables developers to manage applications across various environments. Docker makes it easy to scale up or down applications as per business requirements and is very dynamic. […]

Mansi B.

Written by Mansi B.

August 17, 2023 | 7 min read

Containers are globally used for building various projects and are highly convenient as they are fast, flexible, and scalable. Docker’s platform adds portability to cloud workloads, is open-source, and enables developers to manage applications across various environments. Docker makes it easy to scale up or down applications as per business requirements and is very dynamic. It’s a cost-effective alternative to hypervisor-based virtual machines and allows enterprises to better tap into their server capacity to achieve their business goals.

 Docker security follows client-server architecture, and the Docker client communicates with REST APIs over UNIX sockets and network interfaces. Docker security includes aspects such as the Dockerfile, Docker daemon, container runtime, and base images, all of which must be secured for optimal data privacy and application performance.

This blog will discuss docker container security, explain how to secure docker containers, and cover the top docker container security tools.

Table of Contents

  1. What is Docker?
  2. What is Container Security?
  3. How Docker Works?
  4. What is Docker Container Security?
  5. How to Secure Docker Containers?
  6. Docker Security Challenges and Risks
  7. Things to Consider During Docker Container Security
  8. Best Practices for Docker Container Security
  9. Tools for Docker Container Security
  10. Conclusion 

What is Docker?

Docker is a software platform designed to help developers build and deploy applications rapidly. Docker packages use containers and has everything ranging from system tools, libraries, tools, and runtime. Docker accelerates application development and makes it easily scalable. Many Fortune 500 companies containerize applications, share, and secure app development using its various tools and unique features.

What is Container Security? 

Docker container images are lightweight, standalone, scalable, and have executable components that can be run anywhere. Containers are self-sufficient packages and share access with the OS kernel, which makes them lighter than VMs. Containerized environments are dynamic, and container security requires automation. Securing container images, host machines, container runtimes, and the build pipelines is essential. 

Container security is a critical component of Docker security and is the process of securing Docker containers and components. It uses a blend of security tools and policies to identify potential risks and take steps to remediate them effectively.

How Docker Works?

Docker standardizes code production and provides an operating system for running containers and deploying them in environments. Docker is the defector industry standard and a container-orchestration platform quickly gaining popularity in the DevOps community for designing modern microservice applications. The Docker container engine uses Linux kernel features such as control groups and namespaces to build containers on top of operating systems and provide OS-level virtualization.

Docker makes it convenient to package applications into containers and manage containers efficiently. 

There are a few important things to note about the platform which are: 

  • It does not replace Chef, Ansible, and Puppet, and it is not a container
  • Docker is not a VM (Virtual Machine) solution or LXC
  • It is not a platform as a service technology 

What is Docker Container Security?

Docker container security presents unique challenges and involves creating a safe environment for all systems over traditional virtual machines. Docker components can be isolated to reduce the risk of lateral movement and prevent hackers from causing data breaches.

It is essential to understand that securing various components from the host to the network is critical when securing docker containers. 

Below we will cover how to secure docker containers.

How to Secure Docker Containers?

The first step to enhancing docker container security is keeping the host and docker up-to-date. It prevents various vulnerabilities and eliminates the chances of threat actors escalating root/administrator privileges. Patching the Docker Engine and Docker Machine is critical to Docker container security.

Docker containers should be configured to have unprivileged access and restrict user permissions. A good practice is using pod security policies and limiting or dropping Linux kernel capabilities. Users can keep docker images secure by performing regular vulnerability scans and reducing risk exposure. Auditing docker directories and files and using APIs and networks for communications is critical. Docker container monitoring is specialized and can enhance visibility and observability in containerized workloads.

Many other security features can be implemented for optimal docker container security. We will discuss that in the following sections.

Docker Security Challenges and Risks

The central container security Docker challenges and risks are:

  1. Unrestricted traffic and un-secure communications
  2. Unprotected or vulnerable Docker container images
  3. Host Kernel Vulnerabilities
  • Unrestricted network traffic – Docker versions allow all unrestricted traffic on networks and may expose sensitive information to the wrong containers. Attackers can hijack multiple containers simultaneously and infiltrate host systems.
  • Lack of Compliance – It can be challenging to manage compliance and automatically enforce it, owing to the continuous and fast-paced growth of container environments and changes in the regulatory landscape.
  • Vulnerable container images– Container images from untrusted or unverified publishers are unstable and may contain malicious code. Unofficial container images in the Docker hub registry may be corrupted.
  • Container breakouts – When a single container gets compromised, the others are affected. This happens when a malicious actor accesses the hosts and breaks out from the compromised container, thus targeting other containers.

Things to Consider During Docker Container Security

Here are some common security risks that occur when managing docker deployments and how they affect them: 

1. Unrestricted traffic and un-secure communications

Some Docker containers may offer unrestricted access by default allowing all network traffic on the same host. It can result in accidental exposure of sensitive data to the wrong containers and increase the attack surface. The top concerns are unencrypted Docker communications and a need for network traffic integrity and confidentiality.

2. Unprotected or vulnerable Docker container images

Docker container images have unknown vulnerabilities and may come with malicious code. Docker images may also come from unverified or untrusted sources, introducing additional vulnerabilities. Over 100,000 open-source Docker container repositories exist in the Docker Hub registry, meaning many unofficial or modified image versions exist. 

3. Host Kernel Vulnerabilities

Host operating systems may not be kept updated or monitored vigilantly. The operating system host kernel can expose the host and all containers, opening it to various security threats. Container breakout is another common problem where the malicious actor can gain root access to the host and escape the isolation of containers, thus allowing them to escalate privileges and access host resources. Developers must check if the host kernel is patched and kept up-to-date before being exploited. 

Best Practices for Docker Container Security

Docker container security encompasses proper configuration of containers, user privileges, and implementing security practices to ensure that containers are fully scalable without compromising integrity and authenticity. Mitigating supply chain risks and minimizing attack surfaces are the top priorities for securing Docker Hub, and Docker container deployments can be protected by applying appropriate threat remediation workflows.

Here are some of the best practices to follow for Docker container security:

  1. Avoid Root Permissions
  2. Reduce Resource Usage
  3. Enable Real-Time Docker Container Security Monitoring
  4. Scan Container Images 
  5. Build Networks and APIs for Security
  6. Use Intrusion Detection and Prevention Tools

1. Avoid Root Permissions

Users should avoid giving docker containers root permissions and not change the default configuration. Allowing root permissions by default introduces security vulnerabilities and can increase the risk of data breaches.

2. Reduce Resource Usage

Docker lets users limit resource usage for each container and can restrict CPU RAM and memory consumption. Resource usage limitations can improve docker container security and enhance performance. By limiting the number of resources being used, attacks are blocked automatically, and services don’t get disrupted. 

3. Enable Real-Time Docker Container Security Monitoring

No Docker security tool can achieve 100% security, but using an agency can significantly minimize the risk of facing vulnerabilities in the infrastructure. 

Many Docker container security tools allow users to perform real-time monitoring of containers and services. Docker containers have many moving components and immutable parts, making enhancing security challenging. Users can improve safety, achieve observability, and gain visibility into environments by enabling real-time tracking of containerized workloads. Another good tip is to scan Docker image ports and network configurations and ensure that roles are assigned to the correct accounts to achieve maximum visibility.

4. Scan Container Images 

Another good tip is to scan Docker image ports and network configurations and ensure that roles are assigned to the correct accounts to achieve maximum visibility. Organizations can also use a third-party registry with built-in scanning features for the best results.

5. Build Networks and APIs for Security

Docker APIs and networks communicate with each other, and it’s important to optimize them for enhanced security. Users can enforce proper security monitoring and policies and block data breaches quickly by implementing the right network and API security practices for containers.

6. Use Intrusion Detection and Prevention Tools

Intrusion detection and prevention tools can help secure Docker containers by mitigating potential advanced threats. It uses machine learning and a rule-based engine to achieve active monitoring and can apply a universal firewall to block all access endpoints.

Tools for Docker Container Security

Several open-source tools are available in the market for managing Docker container security. Auditing Docker containers against security benchmarks and remediating hidden vulnerabilities early on are keys to effective threat mitigation. 

Below are the top Docker container security tools in the industry: 

1. PingSafePingSafe was created by one of the world’s top 5 ethical hackers and was initially developed to detect, identify, and remediate cloud-based infrastructure flaws and vulnerabilities. It is an excellent tool for managing Docker container security and can scan Docker ports and container images. It also allows users to define their container security policies, implement them, and enforce shift-left security. 

Popular features in PingSafe include:

  • Zero-day vulnerability assessments, threat watch dashboards, and VM snapshot scanning
  • Graph-based visualizations of ECS/Kubernetes clusters, CI/CD integration support, and scanning embedded secrets in host VMs and container images
  • IaC deployment and configuration checks, IaC script monitoring, and support for CloudFormation, Terraform, Helm, and other IaC templates
  • Automated threat remediation for cloud misconfigurations, real-time secret scanning for over 800+ types of embedded secrets, and agentless vulnerability management
  • Continuous cloud compliance monitoring for 20+ industry standards and regulations such as ISO 27001, PCI-DSS, NIST, and more.

2. Dive – Dive is another Docker container security tool that monitors permissions for Docker images and uncovers hidden layers. It gives insights into resource utilization and is best suited for Ubuntu OS environments. 

3. InSpec – InSpec is an open-source Docker container security monitoring framework that lets users scan and verify images. It can check for continuous security compliance and matches container images with several benchmarks like the CIS Docker Benchmark and Linux baseline. 

4. Trivy – Trivy can scan Docker images in minutes, file systems, and git repositories. It can detect Docker vulnerabilities, scan libraries, and be installed in Linux distributions. Trivia can also fix misconfiguration issues, CVEs, IaC security flaws, and problems with software licenses and hardcoded secrets. It is available across common distribution channels online and can be integrated with the VS Code plugin, Kubernetes operator, and GitHub Actions.


Docker container security can be simple, and there are strategies organizations can implement to improve security measures. Using a good vulnerability scanning tool for scanning registry components, directories, and images can go a long way toward threat detection and remediation. Docker scanning tools will give a complete overview of resources, streamline identity and access management, and monitor roles so threat actors cannot exploit permissions.