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Container Security Scanning

Container security scanning is a process that systematically analyzes container images for vulnerabilities and security issues, allowing developers to address potential threats before they escalate into breaches.

9 min read

What is container security scanning?

Container security scanning is a process that systematically analyzes container images for vulnerabilities and security issues, allowing developers to address potential threats before they escalate into breaches. In the fast-evolving landscape of software development, container security scans have emerged as a pivotal way to maintain the integrity of applications.

Container security scanning is vital in DevOps and containerized application environments. This new paradigm demands security measures beyond those for traditional architectures, as containers encapsulate application code and dependencies, posing unique risks. Efficient container scanning integrates into the CI/CD pipeline, identifying vulnerabilities early and maintaining development speed without compromising security. 

This article delves into container security scanning mechanisms, highlighting their role in software development, and discusses tools and strategies for effective integration into DevOps workflows, including an analysis of open-source security tools and comprehensive implementation strategies.

Benefits of container security scanning

Adopting container security scanning is not just a fleeting trend. In reality, it’s a necessary strategy in today's DevOps landscape. Here's why it’s crucial to integrate container security scanning tools into your container workflow:

Early detection of vulnerabilities

Container security scanning plays a crucial role in early vulnerability detection within the software development life cycle. By scanning images during the build phase, it preempts potential breaches and system compromises, addressing security issues before deployment. This proactive approach not only reduces the risk of costly security incidents but also minimizes the financial and reputational damage. Remedying vulnerabilities early is significantly less expensive than post-deployment fixes, making container security scanning a cost-effective investment for long-term security.

Building trust with end users and stakeholders

In today's digital era, trust is synonymous with value. With data security at the forefront of users' minds, organizations that adopt comprehensive security protocols, such as container security scanning, showcase their dedication to protecting information. This commitment can increase trust among end users and stakeholders, who can be assured that the software they use or invest in is continuously monitored and secured against known vulnerabilities.

As we’ve seen, security scanning is a strategic asset that underpins containerized applications' reliability and integrity. By embedding these practices into your container workflow, you can balance the speed and dynamism of DevOps and the uncompromising demand for security in the digital ecosystem. 

What can container scanning detect?

Container security scanning is a multi-dimensional check that examines various layers within a container image. Let’s take a closer look.

Anatomy of a container image

A container image is a blueprint for creating a containerized environment. It encompasses all the essentials for the application's operation: the code, runtime environment, system libraries, and configurations. However, each layer of the image, from the base operating system to the application layer, can introduce potential vulnerabilities.

Commonly exploited vulnerabilities: From OS level to application dependencies

Container images can inherit vulnerabilities from various sources:

  • Operating system vulnerabilities: OS vulnerabilities describe security issues found within the base layer of a container. Since containers share the host OS's kernel, any vulnerability at this level can be critical.

  • Vulnerable application dependencies: Libraries and packages that applications depend on may contain known vulnerabilities. These are often disclosed in public databases and can be exploited if the dependencies are not regularly updated.

  • Configuration flaws: Misconfigurations in container setups are not flaws in the code; they are mistakes in a container’s build and/or deployment. These flaws can lead to serious vulnerabilities.

The role of the CVE database in vulnerability detection

The Common Vulnerability and Exposure (CVE) database is a publicly available catalog of security threats identified in software. Container security scanners leverage this list to compare the components within a container image against known vulnerabilities. When a match is found, it's flagged for review and remediation.

An example of a hosted container image with multiple vulnerabilities

That’s why the CVE database is a critical part of vulnerability detection: It provides a comprehensive and constantly updated list of known security issues. By referencing the CVE list, scanners can provide developers with up-to-date information about the security posture of their containers. Through scanning, vulnerabilities can be systematically identified and categorized based on their nature and severity, information that’s crucial for prioritizing remediation efforts.

How does a container security scanner work?

Container scanners are sophisticated tools that employ various techniques to uncover vulnerabilities. Understanding how these tools function can empower developers to integrate them effectively into their CI/CD pipelines. Here's a breakdown of the key processes involved in container security scanning:

Image retrieval and decomposition

First, the scanner retrieves a container image from the registry where it's stored. The scanner then decomposes the image into its constituent layers, which typically include the base image, application code, and dependencies. Decomposition is essential because it allows the scanner to examine each layer in isolation, identifying any areas where vulnerabilities might lurk.

Signature-based vs. behavioral-based scanning techniques

Scanning techniques generally fall into two categories:

  • Signature-based scanning: This method relies on predefined patterns of known vulnerabilities, which are known as signatures. The scanner checks the components in a container image against a database of these signatures (like the CVE database). If there's a match, it indicates that the component may be vulnerable.

  • Behavioral-based scanning: Unlike signature-based scanning, behavioral-based scanning doesn't look for known patterns. Instead, it analyzes the behavior of the components when a container is running, looking for anomalous activities that might suggest a security issue (think unexpected network traffic or processes that shouldn't be running).

Handling false positives and false negatives

No scanner is foolproof, and both false positives and false negatives can occur.

  • False positives happen when the scanner incorrectly identifies a component as vulnerable. False positives are a time sink and can lead to alert fatigue.

  • Conversely, false negatives occur when the scanner fails to detect an actual vulnerability. This is more dangerous than a false positive because it means a real threat could go unnoticed and unaddressed.

Scanners incorporate several strategies, such as cross-referencing findings against multiple databases, applying heuristics, and using machine learning to improve over time. To mitigate the risks associated with false positives and false negatives, scanners continually refine their algorithms and detection methods, striving to strike a balance between minimizing false alarms and ensuring no genuine vulnerabilities are overlooked.

To sum up, the operation of a container security scanner is a complex interplay between image analysis, vulnerability matching, and behavioral evaluation. This interplay is designed to provide a comprehensive view of the security status of container images, allowing for informed decision-making about addressing potential risks. 

Next, we'll discuss the different types of container security scanning and explore the open-source tools available to developers.

Different types of container security scanning

Because containerized applications necessitate a multifaceted approach to security scanning, there are several types of scanning, which each target different aspects of container security

Image scanning

Image scanning examines the container images themselves, often before they are deployed. Here are three key concepts related to image scanning:

  • Base image vulnerabilities: Many containers are built from base images that can contain vulnerabilities. Container image scanning tools check these base images against known vulnerabilities in databases (like the CVE list) to ensure they don't have any outdated or compromised components.

  • Application dependency checks: Application dependency checks scan the libraries and packages the application within the container relies on. This type of scan also analyzes the software bill of materials (SBOM) to identify outdated libraries with known vulnerabilities.

  • IaC scanning: This process involves the examination of infrastructure as code files, such as Dockerfiles, to validate configurations and detect potential misconfigurations or embedded secrets. IaC scanning helps ensure that the infrastructure provisioning scripts are secure and adhere to best practices, preventing the deployment of vulnerable containers.

Runtime scanning

Runtime scanning (scanning that takes place while a container is active and running) has the following targets:

  • System calls and processes: Runtime scanners observe the system calls running containers make: If a container attempts to make an unexpected system call, it could indicate the presence of malicious activity.

  • Anomalous behavior in real time: This type of runtime scan looks for deviations from regular operation, which could suggest an intrusion. Anomalous behavior might include spikes in network traffic or unauthorized changes to files or configurations.

Compliance scanning

Compliance scanning ensures that containers meet specific security standards and best practices:

  • Mapping to industry standards like CIS or NIST: Compliance scanners check container configurations against industry standards, such as those set by the Center for Internet Security (CIS) or the National Institute of Standards and Technology (NIST). These checks help you verify that containers are secure and that they’re configured in line with recognized guidelines.

  • Custom compliance checks for enterprise needs: Enterprises often have unique compliance requirements, so scanners can be configured to check for specific controls and policies that align with internal security protocols.

The blend of image, runtime, and compliance scanning provides a comprehensive security posture, addressing vulnerabilities all the way from development to deployment and operation. This holistic approach maintains security across the entire container life cycle.

Example of a compliance dashboard reporting current compliance posture against a CIS framework

Best practices for container security scanning

Effective implementation of container security scanning requires more than just choosing the right tools; it calls for a strategic approach to integrating security principles into the container life cycle. Let’s examine four key best practices:

1. The shift-left philosophy: Scan early in the development life cycle

Conducting security checks late in the development cycle leads to costly and time-consuming fixes. The shift-left approach promotes the integration of security processes at the earliest stages of the software development life cycle. By doing so, vulnerabilities are identified and remediated sooner—saving time and money, reducing the risk of security incidents post-deployment, and promoting a security-first mindset among developers.

# Sample integration of a security scanner in GitLab CI
stages:
  - build
  - scan
  - deploy

build:
  stage: build
  script:
    - echo "Building the container image..."
    - docker build -t my-image .

security_scan:
  stage: scan
  script:
    - echo "Scanning the container image for vulnerabilities..."
    - trivy image my-image
  allow_failure: true

deploy:
  stage: deploy
  script:
    - echo "Deploying the container image..."
    - docker push my-repo/my-image:latest

2. Adopt continuous scanning

Because new vulnerabilities are constantly being discovered, a one-time scan cannot guarantee long-term security. Continuous scanning involves regularly scanning container images and running containers to catch new vulnerabilities as they emerge. By adopting continuous scanning, you always know the security status of your containers, minimizing the window of opportunity for attackers.

# Example cron job entry to run a daily scan on a container image
0 2 * * * trivy image my-repo/my-image:latest >> /var/log/trivy_scan.log

3. Prioritize your vulnerability alerts

Not all vulnerabilities pose the same risk, and addressing them all at once isn't feasible. Efficient allocation of resources can be achieved by prioritizing vulnerabilities according to their severity, exploitability, and their specific impact on your environment. When critical security issues are addressed first, you can optimize your remediation efforts.

# Pseudocode for processing and prioritizing vulnerabilities
for vulnerability in scan_results:
    if vulnerability.severity == 'CRITICAL' and is_exploitable(environment):
        raise_alert(vulnerability)
    elif vulnerability.severity in ['HIGH', 'MEDIUM'] and affects_production_code():
        schedule_for_remediation(vulnerability)

4. Foster collaboration: Bridging the gap between DevOps and security teams

Historically, there has been a divide between development teams (DevOps) and security teams. Encouraging collaboration between DevOps and security teams creates a culture where security is a shared responsibility and is integrated into all aspects of the development and deployment process. The benefits are huge. Collaboration results in a more robust security posture and establishes security as a key component of quality.

# Example Slack notification command for a found vulnerability
curl -X POST -H 'Content-type: application/json' --data '{"text":"A critical vulnerability has been found in the latest scan. Team collaboration is required for immediate action."}' https://hooks.slack.com/services/T00000000/B00000000/XXXXX

Spotlight on Wiz container security

Containers, by their very nature, are always evolving within IT infrastructures. With this fluidity comes an ever-shifting threat landscape. Because threat actors continually devise new strategies to exploit vulnerabilities within container environments, you need a solution that is both comprehensive and adaptive. Enter Wiz for Containers.

Wiz provides the tools and insights necessary for continuous assessment throughout the entire software development life cycle. With our comprehensive security solution, everyone on your teams can get a holistic view of container security, making insights easy to access—and easy to act on.

Ready to enhance your container security? Don't wait for a breach to highlight the importance of security in your containerized environments. Take the first step towards proactive defense and sign up for a free Wiz container security demo today. Experience firsthand how Wiz can transform your security posture and keep your containers safe.

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