How to Secure Containers – A Comprehensive Guide

Containerization is a word often thrown around when talking about cloud computing and DevOps. Popular services like Docker and Kubernetes have accelerated the use of containers for developing and shipping software. But what is containerization?

In essence, a containerization is a form of virtualization. The software code is packaged and required dependencies and operating system libraries in an isolated space referred to as a “container.” To put it simply, whatever requirements a piece of code has, are bundled together in the form of a package that can essentially run on any infrastructure without requiring any refactoring.


Containerization enables rapid development and deployment of software applications while ensuring continuous updates and improvements. Today, we’ll learn why container security is important and how you can do that!

Why is Container Security Important?

As with any software component used by millions globally, they are securing containers is a concern for the modern software world. Many factors contribute towards making containers secure and free from vulnerabilities and potential exploits.

Under normal circumstances, containers are swapped frequently; therefore, updating and patching them might seem relatively simple. However, frequent container updates come with an inherent drawback -- each update could open doors to potential attacks and vulnerabilities.

A security compromise could not only cause the loss of millions of dollars but can also put customer data at risk -- something no business would ever want. For this reason, securing containers is vital. The best practices for container security target the entire containerization process to ensure its integrity and reliability.

How to Secure Containers?

Now that we’ve established the importance of securing containers, we’ll explore the areas of threats for containers while also learning how to mitigate the associated risks at each part of the process.

1.   The Host

The first and foremost part of the container is the host. So, securing it is integral for the security of the container. Securing the host begins with the selection of an operating system. It is advisable to choose a distributed operating system for the host. Such systems are optimized to run containers efficiently.


If Linux or Windows is being used to run containers, the security of these systems should be hardened, and extra services should be disabled to minimize potential threats. Furthermore, it is recommended to employ monitoring and security tools to keep an eye on the host’s performance.

Once the container goes into production, interaction with other containers becomes unavoidable. In order to monitor internal traffic, tools like intrusion prevention systems (IPS) can prove very effective for tracking communications and preventing any exploits.

2.   Securing the Application

While a container is running in production, data is being processed for the underlying application. This may include several different activities, from generating logs to caching files. It must be ensured that these activities are not malicious in any way. For this purpose, anti-malware tools can be helpful for securing the applications running inside of these containers.

A common usage pattern in this regard is known as virtual patching. The IPS usually performs it. If the IPS detects that a potential vulnerability is being exploited, it will drop the associated packets. This can buy the security team critical time to fix the problem at hand and avoid catastrophic results.

3.   Monitoring Your Application

Even with the presence of virtual patching and anti-malware software, it is not certain that your application is entirely free from vulnerabilities. Therefore, a runtime application self-protection (RASP) can be a valuable tool to have in your arsenal.


These security controls incorporate various utilities like monitoring Structured Query Language (SQL), URL verification, etc. This alone can save your application from common exploits like SQL injection and Cross-site scripting. In addition to these, an important feature of RASP is detecting the actual line of code, creating the security exploit. This level of awareness can result in immediate action being taken to secure the application before any further damage.

4.   Secure Container Management Stack

Another component often overlooked while securing containers is the container management stack. When securing the management stack, a container registry can be used to enforce security standards in your deployed container. It is recommended to run the registry on a system with hardened security to avoid the risk of it being compromised.

Additionally, Kubernetes can allow for the application of strict policies for container sharing and collaboration. Not only that but it can also be configured to implement network security policies for further strengthening the security of your containers.

5.   Container Scanning

Now that you’ve set up and deployed your containers and have put up security protocols in place, the next step is to ensure that the images you are using for your containers are reliable and free from vulnerabilities before being used in production.

For this purpose, an image scanning workflow is used by most organizations. As the name implies, these tools scan the contents of a container and perform checks to ensure everything is working as expected. In this way, container scanning becomes an automated process in the workflow that the developers don’t have to worry about.

6.   The Build Pipeline

Most, if not all, organizations today employ some form of continuous integration and delivery system. These systems have made it possible to develop and ship software at a tremendous pace while making it easier to push updates and track bugs.

However, these pipelines themselves have become the target of exploiters. The final piece of the puzzle is to ensure that your continuous integration/delivery pipeline is secure and your security controls are up to date. For this purpose, a strong control strategy coupled with restricted access can mitigate the risk of attackers gaining access to your code repository or build server -- something which can prove very dangerous. It might also be helpful to audit who has access to your code repository and for how long.

Securing all these components is essential for protecting the integrity and reliability of deployed containers. These security practices apply to most containers used in production today. However, there are some specific security practices recommended for Docker and Kubernetes containers that can be adopted in conjunction with these to ensure the complete coverage of all potential vulnerabilities.

Challenges When Securing Containers

According to a recent study conducted by McAfee, around 80 per cent of companies with more than 500 employees use containers, while only 66 per cent of them have a security strategy in place. The biggest challenge in effectively securing containers is the frequency at which these containers and microservices are deployed.

Secondly, applications using containers tend to be broken down into smaller services that communicate with each other. It is, therefore, difficult to effectively monitor these interactions and control access.

Finally, another challenge for securing containers is the lack of mature security tools. It is difficult to find ready-made solutions, and if such solutions exist, they don’t cover all use-cases a real-world application might face.

In Conclusion

Containerization has revolutionized how we develop, ship, and maintain software. However, securing containers demands a fundamental approach to security. It requires careful observation and monitoring. It also involves using the best practices and tools to ensure that all weak points are adequately reinforced.

Securing modern applications requires consistent planning from the beginning and can no longer be left out as a last-minute activity. Trusted security controls and automated processes can aid collaboration and improve the quality of the final product.

Stefan Richard is one of the folks who can't have a life without technology, especially Microsoft products. He has more than 12+ experience in Information technology. He worked as IT trainer, network/system administrator and IT Infrastructure manager. Stefan is the co-founder of HecticGeek.

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