First off, How Do Containers Work?
Containers are a technique of operating system virtualization that allow you to execute a program and its dependencies in resource-isolated processes. These separated processes may function on a single host without sight into the other's processes, data, and network. Usually every container instance provides only a single service or discrete activity (namely a microservice) that represents one element of the application.
Containers, however, are immutable, which means that any modifications made to a live container instance will be need to be done on the container image and then redeployed else whatever was done will be temporary.
This functionality enables for more efficient development and a better degree of assurance when deploying containerized apps.
Secure the Host Operating System
Container security begins at the infrastructure layer and is only as robust as this layer. If attackers breach the host operating system (OS), they may penetrate all operations on the OS, as well as the container runtime.
For the most secure architecture, you should build the base OS to execute the container engine solely, with no other processes that may be hacked.
The host operating system of choice for the great majority of container users is a Linux distribution.
A recommended practice is often to use a host OS designed specifically for containers to lessen the attack surface. Red Hat Enterprise Linux CoreOS, which is hardened with SELinux and provides process, network, and storage isolation, powers contemporary container systems like Red Hat OpenShift.
You should always maintain the host operating system patched and updated to further fortify the infrastructure layer of your container stack and enhance your overall security posture.
Securing the Host OS: Best Practices
Some recommended practices to take into account while protecting the host OS are included in the list below:
Choose an OS
Because they often come with security features like activated SELinux, scheduled updates, and image hardening by default, container-specific operating systems should be taken into consideration if you are running containers on a general-purpose operating system. One such free, open-source, Linux-based OS made specifically for running containers is Bottlerocket from AWS.
You will have to handle each security feature on a general-purpose OS on your own. Applications that are not containerized or unneeded system services should not be running on hosts that run containers. Additionally, you need to routinely check for vulnerabilities in your host operating system. Update the OS and install fixes if you discover any vulnerabilities.
Consider OS Updates and Vulnerabilities
Once you've decided on an operating system, it's critical to define best practices and software to verify the versioning of the underlying OS's packages and components. Be aware that if you decide to utilize a container-specific OS, it will include parts that might become weak and need to be fixed. You should periodically scan and check for component updates using the tools offered by the OS vendor or other reputable businesses.
Even if a specific OS package may not have security flaws, you should upgrade components if the vendor advises doing so. Another option is to re-deploy an updated OS if it is more convenient for you. The host should continue to be immutable while running containerized apps, just as containers should. Data that is persistent just inside the OS shouldn't be the case. Adhering to this recommended practice will significantly lower the attack surface and eliminate drift. Finally, container runtime engines like Docker constantly upgrade their software with corrections and new features. Applying the most recent patches might help to minimize vulnerabilities.
Set User Access Permissions
All authentication straight to the OS should be inspected and reported. You should only allow access to the relevant people and utilize keys for remote logins. And you should install firewalls and enable access only on trustworthy networks. You should also put in place a solid log monitoring and management procedure that ends in a dedicated log storage server with controlled access.
Furthermore, the Docker daemon needs 'root' access. To offer access permissions to a user, you must specifically add that person to the 'docker' group. Remove any users who are not trusted or do not need credentials from the 'docker' group.
File System Host
Ensure that containers are operated with the bare minimum of file system permissions. Containers should not be able to mount sensitive folders on the file system of a host, particularly if they include OS configuration data. Because the Docker service runs as root, an attacker might execute any command that the Docker service can perform and possibly acquire access to the whole host system.
Container/Docker Runtime Environment Audit Considerations
Audits should be performed on the following items:
- Activities of container daemons
- These files and folders should be monitored
- /var/lib/docker
- /etc/docker
- /etc/docker/daemon.json
- /etc/default/docker
- /usr/bin/docker-containerd
- /usr/bin/docker-runc
- docker.service
- docker.socket
Docker Image Security
Before launching a Docker container, you need know precisely what's inside. Many of the issues involved with assuring Docker image security may be solved simply by adhering to recommended practices for protecting Docker images.
What Exactly Are Docker Images?
So, first and foremost, what are Docker images? Simply described, a Docker container image is a collection of data that comprises all of the files, software packages, and information required to execute a container instance. An image is essentially a template from which a container may be created. Images are immutable, which means they cannot be modified after they have been created. If someone made a modification, a new picture would be created as a consequence.
Layers are used to construct container pictures. The base layer includes the image's basic components and serves as the basis for all subsequent components and layers. Base layers are often modest and representative of popular operating systems.
Container images are often maintained in a centralized place known as a registry. Developers may use registries like Docker Hub to store their own images or search and download pre-created images.
Docker Image Protection
Incorporating static analysis tools into your container images gives insight into any potentially susceptible OS and non-OS programs. Through policy checks inside a secure container development process, you may utilize an automated tool like Anchore to control whether you want to promote non-compliant images into trusted registries.
Policy enforcement is critical because susceptible pictures that find their way into production settings offer major dangers that may be expensive to address and can harm your organization's reputation. Concentrate on the security of the programs that will operate inside these images.