5 Steps to Secure Your Containers Against Vulnerabilities

Container technology is fast becoming the mainstream medium for application deployment. This skyrocketing popularity can be credited to the massive economies of scale that containerization offers, especially when combined with Kubernetes, microservices architecture, and DevOps.

As you may already know, containers start and stop much more easily compared to virtual machines. This enables container-based applications to rapidly adapt to fast-changing demands in their environment. Secondly, these applications are incredibly easy to scale because developers can add or subtract containers as the environment dictates.

A Close-Up of Container Security

Container adoption may be the new strength for most modern application developers. But with new technology comes new potential areas of attacks and containers are no exception.

Theoretically, containers-based applications should be more secure than the traditional monolithic applications. This is because an affected code can be easily removed and replaced without affecting the performance of other codes.

However, don’t forget that multiple containers create an extra level of dependency that may not be so easy to monitor continuously. Security is still a major concern in containerization particularly because a vulnerability causing lateral access to stored data may go unnoticed until significant damage is done. This explains why vulnerability management should be at the core of every containerization campaign.

How to Secure Your Containers Against Common Vulnerabilities

1. Make Security a Part of Your CI/CD Pipeline and Tools

The Continuous Integration Continuous Delivery in container technology offers a crucial bridge that links developers with the end-users. This pipeline brings together key application development stages (plan, code, build, test, release, deploy, operate, and monitor) to improve the efficiency of the team.

Everything that goes around the CI/CD workflow rotates around the code. That’s to say that even the smallest of all vulnerabilities in the pipeline puts the entire project at the mercy of digital attackers and malicious actors. This suggests that securing the CI/CD pipeline should be among the first steps in your container security strategy.

The concept of securing the CI/CD pipeline takes 3 different but complementary concepts:

1. i) Security of the pipeline– this involves securing the CI/CD framework as a whole. It includes determining who can access the pipeline and what changes they are capable of making.
2. ii) Security in the pipeline– this concept takes security analysis further by checking for errors and vulnerabilities right inside the code. When implementing security in the pipeline, developers should employ code quality static tools to analyze the application for vulnerabilities. Security in the pipeline also requires doing regular manual peer code reviews. These are formal inspections that help point out any mistakes in a fellow programmer’s code.

iii) Security automation– manual operations make it practically impossible to fix a vulnerability as soon as it occurs. That’s why most experts recommend automating the CI/CD security process. This is necessary for doing regular vulnerability analysis and remediating problems promptly.

2. Lock Down the Operating System

Another crucial step in securing your container applications is to run them on a bare-bones operating system. Running containers on a bare-bone (a.k.a bare metal) system is all about minimizing the attack surface as much as possible. You do this by locking most of the OS installed components that the containers won’t require.

There is a bevy of other advantages of running containers on a bare-bone OS besides the security aspect. To begin with, it offers an excellent way of cutting down the overhead cost of the host OS. If you’ve been paying a premium for the hypervisor, a bare-metal OS will cut this cost significantly. Not to mention, containers inherently are more efficient when utilizing the available infrastructural resources.

3. Take Advantage of Image Admission Controls

An important container vulnerability management practice is to ensure that vulnerable and unauthorized images are not deployed into the orchestrator’s cluster or pipeline in general. Image admission controls let you set an image policy requirement, including where the images will be obtained from and whether they have the content trust properly applied. If the images don’t meet your requirements, the pods are not deployed or updated.

Kubernetes offers you several image admission controls to ensure that the images are aligned to your desired workflow. You may use one or a combination of several controls depending on the level of security that you need. Here are the most common:

• Vulnerability profile– a security profile is created and the images are scanned based on the listed vulnerabilities.
• Trusted registry– only images from a trusted registry are deployed.
• Image signatures– the signature of the image is verified before being approved for deployment.
• User or service account– this control gives limits on which accounts can deploy the containers.

4. Keep Your Images and Containers Light

Containers usually come with all the dependencies and executables necessary to run an application: code, libraries, system tools, runtime, and settings. By their nature, containers are generally lightweight because they share the host’s OS system kernel. But you may end up building huge images, which may negate most of the benefits of Docker services, including portability and fast deployment. From a security perspective, keep in mind that your container’s attack surface grows as the container gets bigger. 

Here are some tips on how to keep Docker images and containers small and lightweight:

• Use fewer layers.
• Ensure that the container boot time is predictable.
• Know how to use Docker cache effectively.
• Consider using small base images that contain only the essential packages that your application needs.
• Consider building your customized base images if you need to create new services frequently.

5. Ensure Regular Security Audits

In an era rife with cyberattacks and threats, creating and maintaining a secure environment should be the number one job for all organizations. Well, the fact that new vulnerabilities keep on popping up means that there’s nothing like a permanent solution to all security issues. Your primary goal when adopting containerization technology should be to minimize security risks across the application delivery stack. 

To accomplish this, you need to regularly assess the current container security best practices to ensure that they are effective in light of the known vulnerabilities. This helps detect and deal with new vulnerabilities as they arise, thereby limiting the scope of breaches.