Container Vulnerability Scanning: Definition & Tutorial

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Container vulnerability scanning allows you to access all containers’ possible security vulnerabilities from a bird’s eye view. The process can be automated for individual container images in order to identify and fix security issues detected in the scan before deployment.

The containerization of applications allowed developers to set up platform-independent and portable apps that can run smoothly in a variety of environments without having to worry about system compatibility. However, similarly to other app development approaches, malicious actors can take advantage of vulnerabilities to access or corrupt confidential information.

How Container Vulnerability Scanning Works

Scanning for security vulnerabilities inside containers can be performed manually or automatically using scanning tools compatible with the container imaging software. Generally, vulnerability and security scans should be conducted regularly and at various stages during the development of the application, and all updates to follow pre-deployment.

The vulnerability scanning process consists of repeatedly analyzing the components of an image looking for redundancies or gaps in security or opportunities for user malpractice.

Some scanning tools are capable of tracing back the vulnerabilities to the parent image and how it interacts with the new contents. But since container technology is still relatively new, identifying what constitutes a security vulnerability during a scan is tricky. Conducting regular scans with the latest version of your scanning software enables you to detect the latest vulnerabilities even after a period of time.

3 Steps to Container Vulnerability Scanning

When it comes to managing the security and present vulnerabilities in containers, there are multiple ways you can execute the scan from scratch.

1. Securing the Application Code

The application development and code are one of the few components of a container image the developer is in full control of. Despite being the first step, scanning and tracking the operation of the container’s code and all its related dependencies takes considerable time and effort, especially when performed manually. 

Focus on spotting errors in the code early on in the development stage before the containerization, integration, and deployment processes. The initial scanning process can be performed before or after the code has been put into a container. 

2. Scanning the Container Image

Imaging has been made easier thanks to the countless trusted images uploaded by verified publishers, especially on the Docker Hub, which has millions of users.

Start by scanning the container images, checking for digital signatures that may indicate fluctuating quality, and minimizing the number and concentration of vulnerabilities before moving to the following step, in correlation to the size of your image.

3. Scanning the Connectivity Layers

The middle layers of a container, which connect the base container image with the application code, tend to contain a lot of the vulnerabilities within a container as they make up the bulk of the layers. Customizing your images by minimizing the number of middle layers simplifies the scanning process, both manual and automatic. 

4 Common Vulnerabilities Detected with Container Scanning

As container technology continues to evolve, so might the number and types of vulnerabilities you can expect to find.

There are a handful of vulnerability types you’re likely to detect when conducting a container image vulnerabilities scan, such as:

1. Image-based vulnerabilities

Container images are static files of executable code built to be immutable. They’re the building blocks of containers and computing systems that ensure reliable deployment every time.

The immutability of container images can result in vulnerabilities from outdated code and builds. Weak points in container images can be exploited to access the container and launch cryptojacking or privilege escalation attacks. 

2. Cryptojacking

Cryptojacking is a type of cybercrime that forces containers to run malicious scripts to mine for cryptocurrency. This vulnerability enables hackers to remotely access your infrastructure’s CPU and GPU resources, gaining root access to the machine.

It doesn’t end at resource exploitation, as the same door can be used to maliciously access sensitive credentials used and stored in the container. This could result in anything from wide-scale and high-accuracy phishing schemes to direct denial of service (DoS) attacks.

3. Privilege escalations

Privilege escalations are vulnerabilities that enable a hacker to access adjoining containers and host systems after gaining access to the initial container image. Multiple vulnerabilities can be exploited to escalate access privileges, from defects in the Linux kernel to low run times in containers.

Oftentimes, this type of attack can be mitigated by ensuring no outdated kernels or system configurations are used in the container. 

4. Application vulnerabilities

Container vulnerabilities can be found in the applications they’re meant to carry. If there are flaws or outdated security techniques used during the early stages of application development, attacks can exploit them.

Application vulnerabilities can range from poorly protected data input points that allow SQL injections to a lack of a buffer between containers in case a hacker attempts to execute arbitrary code.

Scanning a Docker Container for Vulnerabilities

With Docker still going strong as the most used and loved containerized application tool, vulnerability tools, both open-source and proprietary, cater to providing the best and most accurate scan results. Scanning a docker container for vulnerabilities enables you to review the entirety of the container image for any issues and vulnerabilities.

There are multiple types of container vulnerability scanning tools and techniques, such as:

User-defined vulnerability scanning policies 

User-defined policies in containers are access and privilege control policies that orchestrate and manage user capabilities of inputting data into an individual container within a pool of containers.

Scanning for vulnerabilities through user-defined policies allows you to customize your security policies based on activities, limiting privilege escalation risks, insider attacks, and users exploiting vulnerabilities.

Identity access vulnerability scanning

Identity access management is the framework that oversees and authenticates the identities of users and develops access to containers and images.

Basing your scanning on container identity access enables you to prevent individual containers from acquiring complete access to the entirety of the infrastructure’s resources.

Network configuration vulnerability scanning

Containers rarely work individually but in a network of containers where communication configurations and rules are essential. This type of vulnerability scan examines your image ports and the associated network communications looking for issues or inconsistencies.

3 Best Container Vulnerability Scanning Tools

Whether you’re looking for a manual container vulnerability scanning tool or a more ready-for-you, automatic solution, the prominence of containerization technology comes with a wide variety of tools.

In fact, the global container security market was estimated at $1.3 billion in 2021. It’s expected to reach an estimated value of $3.6 billion by 2026, trailing a Compound Annual Growth Rate (CAGR) of 22% over the analysis period.

Some of the leading container vulnerability scanning solutions on the market include:

1. Anchore

Anchore is an open-source tool for Docker images deep analysis. Its analysis engines run on Kubernetes, Rancher, Amazon ECS, and Docker Swarm depending on the type of containers you’re looking to scan.

As a container inspector, the Anchore platform enables you to analyze, inspect, and perform security scans for your containers, comparing the results against pre-set security policies and standards.

2. Dagda

Dagda is an open-source container vulnerability scanning tool that can be used to analyze performance and detect weaknesses such as malware, viruses, and Trojan threats. For security, it employs the ClamAV antivirus engine for viral vulnerabilities.

The Dagda tool supports a number of static analysis techniques for detecting and identifying security vulnerabilities. It also provides comprehensive reports on the state of the container.

3. Snyk is a container vulnerability scanning and analysis tool by the Boston-based cybersecurity company under the same name. It automates the scanning of container images depending on your project’s settings and how often you deploy updates.

Additionally, and based on the history of previously detected vulnerabilities in your containers, operating system, and application dependencies, Snyk emails you a report of your container’s security state.

Bottom Line: Container Vulnerability Scanning

Container vulnerability scanning is an essential part of the building and deployment of containerized applications. The scanning tools, both automatic and manual, enable you to detect and fix vulnerabilities and issues present at various parts of your containerized architecture before they’re deployed or released for large-scale use.

There are different types of vulnerabilities you’re likely to find during your scan, and dedicated vulnerability scanning tools can simplify the process through advanced security, analysis, and reporting tools.

Read more: 8 Types of Vulnerability Scanning Tools Explained

Anina Ot
Anina Ot
Anina Ot is a contributor to Enterprise Storage Forum and Datamation. She worked in online tech support before becoming a technology writer, and has authored more than 400 articles about cybersecurity, privacy, cloud computing, data science, and other topics. Anina is a digital nomad currently based in Turkey.

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