Containers for application development and development have been well documented in cloud environments, and modern enterprises are shifting towards cloud-centric architectures. Container Scanning is a subset of container security and a foundational security measure to secure containerized DevOps workflows.
Not all containers are created equal, and many images can be extracted from untrusted sources and public repositories. They can add new threat vectors, contain malicious components, and present unknown risks.
This blog will discuss the basics of container scanning and why it is critical to container security. We will also cover common container vulnerabilities and different container scanning methods and walk users through how to implement them. Let’s dive into it.
What Is Container Scanning (Container Image Scanning)?
Container Scanning uses cutting-edge security tools for analyzing the various components of container images layer by layer to detect potential threats.
Container Scanning solutions identify vulnerabilities and check for hazards by leveraging global databases. It identifies exploits in cloud-native applications and ensures that development teams can find and fix vulnerabilities early on before they get used. These solutions enable shift-left security measures from the beginning, conduct analytics, and provide recommendations for remediating vulnerabilities.
Why Do Container Scanning?
Containers contain multiple images which inherit vulnerabilities from base images, including all possible misconfigurations, malware, and other security flaws. Enforcing shift-left security begins by analyzing dependencies and packages within container images to eliminate threats and prevent them from being deployed into the production pipeline.
It is essential to use a container scanner to identify and fix vulnerabilities in container images before they escalate and cause serious issues. Not running proper container scans can leak sensitive credentials, cause data breaches, and lead to other security compromises.
What Are Common Container Vulnerabilities?
Containers are changing how enterprises build, deploy, and use applications. They increase efficiency and portability and allow users to run software without worrying about suitable operating systems, settings, or production environments. Containers are secure by default but are exposed to certain risks like any other security vulnerabilities.
The most common container security vulnerabilities are:
- Untrusted containers – Untrusted containers mainly consist of containers that run software from untrusted or unverified sources. These containers may carry malicious code and upload them to public repositories, causing attackers to gain unauthorized access to networks.
- Insecure configurations – Machines that run containers may be vulnerable to OS-level attacks, so properly updating and configuring the host OS is essential. The insecure design also includes privilege escalation attacks and misconfigured containerization layers.
- Secrets management – Containers that don’t protect secrets are prone to intrusion on every level. Insecure API keys and tokens are the primary reasons behind secret management flaws. Not rotating private keys regularly can lead to attackers figuring out credentials and gaining access to resources they aren’t supposed to.
Types of Container Security Scanning
Container images can come from various sources, which is why maintaining image trustworthiness is crucial. To achieve total security throughout the lifecycle of your application before deployment and production, it’s essential to implement container scanning in the following three areas:
1. Container Registry Scanning-Container application registries store thousands of images built from different sources. The registry includes third-party locations; a single threat can affect the entire application. Continuously scanning the container registry for changes and vulnerabilities is critical to maintaining container security. This has to be automated, and every image needs to be checked to identify potential threats.
2. Runtime Scanning-Scanning containers at runtime identifies new CVEs, detect new vulnerabilities, and immediately report them to security teams. Automated runtime scanning can prioritize risks across container environments and enhance overall runtime protection. It keeps containers in secure states and mitigates anomalies by establishing baselines.
3. Vulnerability Scanning-Vulnerability scanning analyzes all the components of containers throughout the entire lifecycle of applications. It is a good DevSecOps practice, and security teams must integrate container image scanning into CI/CD pipelines for effective threat detection and remediation. Vulnerability scanning spots vulnerabilities in code before it enters into containers and blocks them to maximize protection.
How to Implement Container Scanning?
Container security scanning is becoming a standardized workflow for monitoring and protecting cloud-native environments and applications. Most developers prefer to separate the execution environment when running container scans using internal tools.
There are three main steps to Container Scanning, and they are as follows:
- Step 1 – Secure the Application Code
- Step 2 – Scan Container Image
- Step 3 – Scan Connectivity Layers
Step 1 – Secure the Application Code
Container application code and development help scan and track container code vulnerabilities and dependencies. It assists in spotting errors early on during the development cycle before containerization, integration, and deployment. The initial application code scan can be done after the code is inserted into the container.
Step 2 – Scan Container Image
Many container image scanning tools are available, and these analyze digital signatures to assess image quality and several vulnerabilities. Container image scanning vets sources and verifies publishers, thus ensuring the integrity and authenticity of these images.
Step 3 – Scan Connectivity Layers
The middle layers of containers contain a majority of security vulnerabilities. Container images can be customized by minimizing the number of layers.
Best Practices of Container Security Scanning
The following are the best practices for Container Security Scanning:
- CLI Local Scanning
- Integrated Automated Scanning into CI/CD Pipeline
- Adopt Inline Image Scanning
- Pin Image Versions
- Scan for Secrets
- Detecting Drifts
1. CLI Local Scanning
CLI local scanning features Docker scanning, making it easier to scan local container images immediately after building them. You can run a CLI scan using the docker scan command, one of the first steps to implement the best container security practices.
2. Integrated Automated Scanning into CI/CD Pipeline
The next step is incorporating automated scanning into the CI/CD pipeline and continuously analyzing container images as they are built. This will help avoid critical security incidents, report failed builds, and identify vulnerabilities.
3. Adopt Inline Image Scanning
Inline image scanning helps keep track of data privacy and secures image credentials. There is no need to stage public repositories; only the scan metadata tool is needed. Inline scanning can be implemented across GitLab, AWS Codepipeline, Jenkins, Tekton, and many other CI/CD tools.
4. Pin Image Versions
Sometimes it’s possible to scan the wrong image as containers have different versions which can be deployed from the same image. It can cause issues with debugging, and if you are using mutable tags, there is a chance for the scan results to become invalid since these tags are prone to constant updates and newer versions.
It’s essential to enforce immutable tags and pin image versions so that regular changes do not affect them. A mix of container image scanning, the OPA engine, and the Kubernetes admission controller can help with this process.
5. Scan for Secrets
Secrets scanning can protect passwords, usernames, and private keys. Scanning secrets before deploying images is a good practice, and users can verify the image sources. Secrets scanning prevents leaks and makes information accessible to secured and containerized workloads. It also makes container maintenance more accessible, and many workflows are designed to monitor Kubernetes clusters using internal tools. Some users prefer to use separate execution environments for analyzing different configurations.
6. Detecting Drifts
Make your container deployments to be immutable by design. It’s important to apply the latest security patches, configuration updates, and deploy new container images in a way that minimize the likelihood of configuration drifts. Use Binary Drift Detection to identify the introduction of unauthorized executables or unwanted modifications. You can integrate drift detection into CI/CD pipelines and it’s recommended to monitor runtime behavior by using runtime security tools. Use container security platforms that provide integrated drift detection, container image scanning, policy enforcement, and container runtime protection.
Why SentinelOne for Container Security Scanning?
SentinelOne delivers industry-leading container security by combining comprehensive visibility, automated threat detection, and posture management for Kubernetes, containers, and cloud-native workloads. SentinelOne Singularity™ Cloud Native Security (CNS) offers agentless container scanning, allowing security teams to detect vulnerabilities, misconfigurations, and exposed secrets across container images before they are deployed. With support for scanning over 750 types of secrets, SentinelOne helps organizations prevent credential leakage and maintain robust code hygiene across GitHub, GitLab, BitBucket, and other CI/CD repositories.
The platform includes Kubernetes Security Posture Management (KSPM), enabling organizations to continuously monitor and enforce security best practices within Kubernetes clusters. SentinelOne detects configuration drift and provides over 2,000 built-in rulesets for major compliance standards such as NIST, CIS, and MITRE, allowing teams to address misconfigurations and compliance gaps in real time. CNS integrates seamlessly into DevOps pipelines to automate policy enforcement and provide actionable insights with minimal disruption to existing workflows.
SentinelOne’s Singularity™ Cloud Workload Security (CWS) extends protection to containerized workloads at runtime, using AI-powered detection to stop attacks—including ransomware, cryptojacking, and zero-days—at machine speed. By combining static analysis, dynamic threat detection, and automated response, SentinelOne enables organizations to defend every surface—VMs, containers, and Kubernetes—across multi-cloud environments from a unified dashboard.
With its agentless CNAPP architecture, SentinelOne empowers security teams to focus on high-impact alerts and verified exploit paths, reducing false positives and operational overhead. Automated onboarding, instant coverage, and unified policy management make SentinelOne an ideal solution for securing containers throughout the entire development lifecycle—from build to runtime.
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Container image scanning best practices such as CI/CD pipeline and OS vulnerability scanning can keep images safe and secure and prevent them from being exploited. Enforcing the best container security is a continuous process and follows an iterative approach from the start of the build to the finish.
It is essential to monitor for threats at all container application development lifecycle stages and prepare for emerging security risks. Scanning containers will uncover hidden exploits, eliminate vulnerabilities, and ensure optimal security by monitoring containerized applications for behavior changes or malicious events. SentinelOne enables out-of-the-box capabilities like audit logging, permissions management, IaC templates support, and more, thus making Container Scanning a seamless experience.
Container Scanning FAQs
Container scanning is the process of analyzing container images and running containers to identify security vulnerabilities, misconfigurations, and compliance issues. It’s a security checkup for your containerized applications.
It examines everything from the base operating system to application dependencies, comparing them against vulnerability databases like the National Vulnerability Database. This helps you catch security problems before they make it to production.
Container scanning detects operating system vulnerabilities in base images, vulnerable application dependencies, and configuration flaws like overly permissive users or exposed ports. It also finds hardcoded secrets like API keys and passwords, malware, and compliance violations against standards like CIS benchmarks.
The scanners check for outdated libraries, misconfigurations in Dockerfiles, and excessive privileges that could be exploited by attackers.
You should integrate scanning into your CI/CD pipelines to catch vulnerabilities before deployment. Use minimal base images from trusted sources and scan both at build time and runtime for comprehensive coverage.
Set up automated scanning with proper alert thresholds, and don’t forget to regularly update your vulnerability databases. Also, implement policies that block deployments if critical vulnerabilities are found.
Container scanners first retrieve and decompose images into their constituent layers, then analyze each component separately. They use signature-based scanning to compare components against known vulnerability databases like CVE, and behavior-based scanning to detect anomalous activities during runtime.
The scanner examines base images, application code, dependencies, and configurations, then flags any security issues for remediation.