We all know that containers are huge in the DevOps and DevSecOps world. Great for packaging applications to make sure they run the same, whatever location you decide to deploy it. However, just like with any new tech, there are some security challenges with containers. Trust me, you don’t want to neglect them.
In this blog, I will guide you through some advanced techniques to lock down your containers in DevSecOps pipelines. By the end, you’ll be a pro when it comes to container security.
Why Container Security Matters
So why bother with this in the first place? Containers are great because you can get code shipped quickly, but they also expose new vulnerabilities for attackers to exploit. When you work with containers, you’re working with a bunch of layers, from the base image down to the application code, and all these layers have to be secure.
Security isn’t something you add at the end of a DevSecOps pipeline. It’s integrated at every stage of the process from development to testing to deployment onward. The container security techniques come into play at that point.
1. Use Trusted Base Images
Picture yourself building a house and using bricks someone else made. You’re hoping those bricks don’t crumble the minute you stack them. The same goes for containers. Similar to a container’s foundation, the base image is an important part of your container’s building block. If the base image is bad, everything built on it is going to break.
Using trusted base images is what I do first when working with containers. These are from official repositories or, better yet, from other repos your organization has verified. If it’s from just any place on the internet, it’s the equivalent of buying food from a food truck that doesn’t have a health code.
Using minimal base images is a good practice. The more attack surfaces an image has, the larger it needs to be. For example, alpine is a super light Linux distribution that you can use instead of using a full operating system image. Fewer things within the image mean there are fewer things that could be vulnerable.
2. Implement Image Scanning in Your Pipeline
After you’ve found a base image, you want to scan it. They’re checking for any suspicious items, which is like going through airport security. Image scanning tools search to see if you have any known vulnerabilities inside your container image.
You can scan images in your pipeline with tools like Clair, Trivy, or even built-in ones of Docker Hub. If there are any vulnerabilities, they’ll tell you if you need to patch those. Don’t just scan once and leave. Because vulnerabilities happen all the time, you should scan regularly.
The earlier you can catch a vulnerability — the easier it is to fix. Along with security issues, fixing them can be a nightmare if you wait until you start to deploy to production. That’s why I always encourage you to automate image scanning as part of your DevSecOps pipeline. It should get automatically scanned every time a new image is pushed.
3. Leverage Container Runtime Security
Just because your container is running doesn’t mean you can sit back and relax now. When it’s live, you have to make sure the components are secure. With this comes container runtime security. It’s like putting security cameras in your house to know if there’s anything suspicious when you’re not there.
One of the big players in this space is Falco, which monitors system calls (basically the requests your container makes to the host system) to detect anything weird, like unauthorized access attempts or strange processes running inside the container.
Let me give you an example. If your container starts trying to modify files that it shouldn’t, runtime security tools can catch that and alert you. That’s important because even if your image is protected when it’s built, all kinds of things go wrong at runtime, especially with zero-day exploits.
4. Use Role-Based Access Control (RBAC)
Moving on, who is allowed to have access to your containers? I’m a fan of role-based access control (RBAC). Imagine different keys for different rooms in a building. Not everyone needs access to every room.
As with Kubernetes and other container orchestration platforms, RBAC is super critical in the world of container orchestration. It lets you control who can do what with your containers. They don’t need to modify network settings or sensitive logs that could break things. The good part about RBAC is you can give users or services specific permissions.
I prefer permissions to be as tight as possible. Quite simply, if you don’t absolutely need access to something, you shouldn’t have it. This principle is known as the least privilege, and it’s a basic rule of good security policies.
5. Network Segmentation for Containers
Network segmentation, much like a highway with multiple lanes, is each lane for a specific type of traffic. For container security, when sending network traffic, we want to be sure that only communicating the services our containers care to communicate to, nothing else.
All your containers don’t need to start talking willy-nilly. That’s a recipe for disaster. The infection could spread from one container to another. With tools like Cilium or Calico, you can have rules on how containers should talk to each other.
Take a web container that simply needs to talk to the backend database but has no need to communicate with other web containers. Network policies ensure that those boundaries are set.
6. Secrets Management
Hardcoding secrets into the images is one of the biggest mistakes I see with containers. Don’t leave the keys to your house under the welcome mat. This is like it! They are secrets like passwords, API keys and sensitive information your application needs.
If you are using containerized environments, use good secrets management tools like HashiCorp Vault or Kubernetes Secrets. These secrets are stored securely and are only accessible to containers that need them. Even better, they can rotate your secrets, meaning it’s harder for any given individual to use them if they were to get their hands on one.
7. Regularly Update Your Images
This sounds obvious, and you’d be surprised how often it’s overlooked. It works just like you should update your phone or computer to protect them.
Those new vulnerabilities crop up all the time, and if you’ve got old images running, you’re just leaving the door wide open for people to attack. What I find useful is to set up an automatic check that alerts me about the existence of a newer, more secure base image or one of its dependencies. I then ensure those updates are deployed in both the next build of my pipeline.
8. Enable Immutable Infrastructure
This is one of those fancy terms you might’ve heard being thrown around, but it’s really pretty simple. Immutable infrastructure means that a container is deployed only once, and then it doesn’t change. You cannot update or fix something in the existing container. Just create a new container.
I love this approach because it reduces the chances of something going wrong due to configuration drift. When containers are immutable, it’s like setting something in stone. You can see exactly what is in every container, and nothing will happen without you knowing it.
Final Thoughts
There you have it! At first, these advanced container security techniques may sound like a lot, but once you get the hang of it, they’ll become second nature. The thing you need to remember about security is that it’s not a one-time deal. But in the DevSecOps pipeline, everything is moving so fast that it’s something you’ve got to keep working at.
Begin small: You could run image scanning and secrets management and add in the rest as time goes on. The more you put out, the more secure your containers (and, therefore, the security of the whole pipeline) will be. After all, it’s better to keep things locked down now to avoid a major headache down the road. Happy securing!
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