Everything you need to know about container scanning | snyk (2023)

Containerized deployments are becoming increasingly popular, and with good reason. Containers enable developers to move faster and reliably deploy applications by turning them into self-contained and portable units of code. However, the adoption of container-based software means responsibility forcontainer securityalso shifts to the developers. Container scanning is an efficient way for developers to ensure their containers are secure.

Let's take a closer look at the basics ofScanning of containersand how automated container scanners work. We will also discuss the types of vulnerabilities that container scanners can detect and how image layers affect container security.

Basics of scanning containers

Vulnerabilities can be introduced into containers in a variety of ways: from the software inside the container, how the container interacts with the host operating system and adjacent containers, the configurations for networking and storage, and more. A container scanner is an automated tool that analyzes these various container components to detect security vulnerabilities.

In addition to vulnerabilities introduced directly by the code and tool you add to an image, problems can originate from other images that your containers rely on. These other images are called parent images or base images (although "parent" is more technically correct). In fact, your container image can be based on a publicly available image that contains known vulnerabilities and malware, especially if you haven't downloaded the image from a verified publisher and authenticated the image publisher and content. Even images from well-known and trusted vendors often have vulnerabilities, but by scanning for vulnerabilities in your image and identifying your parent images and their vulnerabilities, you can often fix a large number of issues with a single change.

Security scanners can be integrated at various stages of development. For example, you can scan potential parent images from your desktop before deciding which one to base your image on. Some tools and IDE plugins will scan Dockerfiles and show alternative images that you could choose that have fewer vulnerabilities or are lighter. Many companies integrate vulnerability scanning for containers into thecontinuous integrationand continuous delivery(CI/CD)-Pipelines, where the "real" images are often created before deployment. By scanning in your pipelines, you can prevent container images with too many issues from being stored in your registries and reaching production. Most teams tooMonitor containerized deployments when running on Kubernetesor another platform. Container security scanning can therefore significantly improve the security of an application without much additional effort for developers.

Scanning container registries is also a great way to reduce the number of vulnerabilities in all commonly used images in your organization. For example,Snyks Integration my Docker Hubcreates a trusted source of public images that developers can use as a basis for the containers they create. You can also monitor your saved images over time to identify newly discovered vulnerabilities in your existing images and prevent them from being deployed to production in the future. Also, you probably have several older images that don't change often, or third-party images stored in your container registry. These images are not passed through your CI/CD pipelines, so scanning from the registry is a good way to determine whether or not these images are safe to use.Ein Registry-Scanner, can therefore give developers confidence in the images they use for containerized deployments.

What types of container vulnerabilities can be detected?

As mentioned earlier, there are a variety of ways that vulnerabilities can be introduced into a container. These container vulnerabilities can range from insecure application code and runtime misconfigurations to network threats and access control issues. Protecting against these threats requires continuouscontainer monitoringand up-to-date knowledge of new vulnerabilities as they are discovered.

Most container scanning solutions use a public source of vulnerability information like thisNational Vulnerability Database (NVD)or theDatabase. These databases publish known exploits in order to activate them automaticallyvulnerability management, security measurement and compliance.

The Snyk security research team enriches container vulnerability data with information that makes it easier to prioritize a seemingly overwhelming number of container vulnerabilities. Factors like whether the container is running on a Kubernetes cluster and if so, how it is configured; the availability of a mature exploit; chatter on social media; and Linux distribution-specific vulnerability details are all factorsSnyk-ContainerInterfaces so you can easily identify which issues matter most.

Effects of container layers on vulnerability detection

Containers are building blocks for modern applications, and one benefit of using containers is that you can build on the work of others. Docker has made this easy for developers and made it easy to share container images through Docker Hub. Docker also provides its own official Docker images covering a wide range of languages ​​and frameworks and other application services. When you build your own images on top of other people's work, your containers end up with multiple read-only layers and a final read/write layer.

Each new layer carries the risk of introducing new vulnerabilities into the container, so it's crucial that the container scanner you use can detect problems layer by layer. It's even better if they link these layers back to the commands or Dockerfile directives they created, as this is a more familiar place for developers to make changes. Since images are almost always built on top of other images (e.g. via the FROM command in a Dockerfile), a container vulnerability scanner like Snyk Container can determine that certain layers are in fact an official Docker image , and intelligently deploy alternatives that reduce the risk of vulnerabilities is even better than just deploying the raw layers. More tiers in a container typically correlate with more packages being installed in a container, and since more packages also correlate with more vulnerabilities and therefore more risks, it's also a best practice to use images that are as lightweight as possible to meet your application needs .

Comprehensive container security

Because containers are layered, comprehensive security requires scanning for vulnerabilities in custom code, open source dependencies, containers and Dockerfiles themselves, and in some cases,Infrastructure as Code (IaC)files. These are the components of modern cloud-native applications, so they are key areas to consider when building a secure development workflow.

Snyk offers a comprehensive set of security scanning tools forCloud native applicationsto ensure development teams can easily find and fix vulnerabilities early in the development process. Snyk seamlessly integrates with existing development workflows to reduce friction when adopting the new security process for development teams. This enables organizationsShift security to the leftand implement security measures for their containers and applications from the start.

More specifically, Snyk Container can not only scan your containers, but also the Dockerfiles themselves to match vulnerabilities with the commands they introduced and to make recommendations and even pull requests to use parent images with fewer vulnerabilities. This deep context of security issues helps developers prioritize remediation based on exploitability to immediately improve the security posture of containers and applications with as few changes as possible.

Frequently asked questions about container scanning

How does container scanning work?

Scanning containers for vulnerabilities typically involves a security tool that analyzes a container image layer by layer to detect potential security issues. Most scanning solutions leverage a database of known vulnerabilities so organizations can stay current as the security threat landscape evolves. Containerized applications are also made up of multiple components, including custom code, open-source dependencies, images, Dockerfiles, and more. Scanning for vulnerabilities in all of these components is critical to comprehensive container security.