Container Scanning | SentinelOne

What is Container Scanning?: Easy Guide 101

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:

  1. Step 1 – Secure the Application Code
  2. Step 2 – Scan Container Image
  3. 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

  1. CLI Local Scanning
  2. Integrated Automated Scanning into CI/CD Pipeline
  3. Adopt Inline Image Scanning
  4. Pin Image Versions
  5. Scan for Secrets

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.

Why SentinelOne for Container Security Scanning?

SentinelOne provides world-class unparalleled protection for multi-cloud infrastructures from development to deployment by leveraging its agentless CNAPP (Cloud-Native Application Protection Platform) tool. It helps businesses run securely on the cloud and facilitates seamless cloud migration from on-premise services. Enterprises choose SentinelOne CNAPP to improve container security because it can perform real-time threat detection and advanced analytics. SentinelOne can detect over 750+ types of hardcoded secrets across platforms like GitHub, GitLab, BitBucket, and more. It offers more than 2,000 built-in configuration rules to handle misconfigurations and eliminate configuration drifts in environments.

It also provides agentless vulnerability management across cloud workloads and comprehensive IaC security. SentinelOne features a complete offensive security engine that gives insights into attackers’ intelligence and offers continuous compliance monitoring for the latest industry standards like ISO, NIST, PSI-DSS, and many more. Setup is a simple process and merely takes minutes. And the user interface is very beginner-friendly and intuitive and doesn’t require any technical experience to get started. Additionally, SentinelOne comes with Singularity Data Lake, Snyk integration, and CI/CD integration support for DevOps workflows. It offers capabilities such as Cloud Security Posture Management (CSPM), Kubernetes Security Posture Management (KSPM), SaaS Security Posture Management (SSPM), Cloud Detection and Resopnse (CDR), Cloud Data Security (CDS), IaC scanning, and others.


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.