What is Container Runtime Security?

Brett Shaw - June 27, 2024

What is <strong>Container Runtime Security</strong>?
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With its ability to streamline application deployment across diverse environments, containerization has become a staple of modern software development. But as the adoption of container technologies like Docker and Kubernetes increases, so does the complexity of maintaining their security. The broad attack surfaces and unique vulnerabilities of container environments demand that organizations take proper security measures.

In this post, we’ll explore container runtime security, looking into key threats and best practices to safeguard containerized applications.

Understanding containerization and the container runtime

Containerization allows developers to package a software application — along with all its dependencies — into a container. The container combines application source code with the operating system (OS) libraries and dependencies required to run that code, and it can be run in virtually any environment.

At the core of containerization is the container image, which is an immutable file containing the application code, libraries, tools, and other files necessary for an application to run. Managing these images securely is crucial, as vulnerabilities within an image can be exploited when containers are instantiated from them.

The container runtime is the software that helps execute containers and manage their life cycle on a host machine. It fetches container images from registries, creates containers, and runs them. Some common container runtimes include Docker, containerd, and CRI-O. Each one provides different levels of abstraction and management tools designed to simplify container operations.

These runtimes handle the operation of containers and ensure that they are isolated from one another and the host system. This isolation is crucial for maintaining the security and efficiency of container operations.

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Why container runtime security is important

Container runtime security is crucial for ensuring containers operate safely from inception to operation. Security threats to container runtimes predominantly stem from shared kernel risks and configuration errors.

In the shared kernel model, containers on the same host operate on one underlying OS kernel. Naturally, this brings inherent risks; a breach in one container could potentially seep over to other containers or the host itself. Without proper security measures in place, an attacker could potentially gain widespread access to critical systems.

Configuration errors also pose significant threats. Because containers are highly configurable, they can be set up insecurely. Errors may include:

  • Inadvertent exposure of ports to the public internet
  • Inadequate authentication controls
  • Incorrect data handling settings

Such misconfigurations provide potential entry points for attackers. Exploiting these vulnerabilities can allow adversaries to gain unauthorized access or disrupt services.

Keys to runtime security

To mitigate these risks, consider implementing several security measures:

  • Continuous monitoring provides runtime protection — with real-time tracking of container activities, organizations can quickly identify and respond to potential threats.
  • Image security ensures that container images are free from vulnerabilities before use.
  • Container isolation — through mechanisms like namespaces and control groups — prevents containers from interfering with one another or accessing unauthorized host resources.
  • Configuration management tools set up and maintain secure container configurations, safeguarding container environments against common vulnerabilities and threats.
  • Regular security audits assess the effectiveness of security measures and the container environment’s overall security posture.

Key threats in the container runtime

Container environments are susceptible to several security threats, including container breakouts, data exposure, and dependency vulnerabilities.

Container breakouts

A container breakout (also known as a container escape) occurs when an attacker gains access to the host system from within a container. This kind of breach compromises the isolation that containers are supposed to provide. With a successful container breakout, an attacker could potentially control other containers or the host itself. Enforcing strict isolation protocols and closely monitoring container activities are essential practices to prevent container breakouts.

Data exposure

On occasion, misconfigurations, weak security controls, or vulnerabilities within the container may cause the unintentional exposure of sensitive information. This can lead to unauthorized access and potential data breaches, severely impacting the confidentiality and integrity of the data handled by a containerized application.

Implementing stringent access controls and conducting regular security audits are key to preventing this exposure.

Dependency vulnerabilities

Containers often rely on external libraries and packages, and these dependencies may contain vulnerabilities. If dependencies are not regularly updated or securely managed, they open up potential attack vectors for malicious users to exploit. A successful exploit could compromise the container and possibly the entire container environment.

Ensuring that dependencies are regularly scanned for vulnerabilities and updated promptly is critical to mitigating this risk.

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Best practices for securing container runtimes

Adopting best practices can significantly enhance the security of containerized environments. Consider the following security best practices, taken from Threats to Containers and Container Technology:

  • Restrict access to the Docker API: Ideally, access to the Docker API should be authenticated and not exposed to the public internet. This prevents unauthorized access and mitigates potential threats from external actors.
  • Leverage just-in-time access: Utilize solutions that provide just-in-time access to containers and their hosts, such as Amazon EC2 Instance Connect. This reduces the risk associated with long-lived credentials and enhances security by requiring multi-factor authentication.
  • Keep applications and libraries updated: Regularly update all applications and libraries within containers to protect against vulnerabilities. Staying current with security patches is crucial in defending against exploits that target outdated software.
  • Extend security monitoring: Implement comprehensive security monitoring for both containers and their hosts. This ensures that organizations can detect any malicious activity or anomalies early, allowing for prompt response and mitigation.
  • Apply the principle of least privilege: Limit permissions to only those necessary for specific tasks within the container environment. This practice minimizes potential damage from breaches or internal threats.

With these strategies in place, your organization will have a strong defense against container runtime environment risks, reducing the likelihood and impact of security incidents.

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Container security mistakes to avoid

Avoiding common security mistakes is just as crucial as implementing best practices. You can further fortify your container environment safeguards by avoiding the following errors:

  • Ignoring basic security measures: It’s not uncommon for default configurations to be insecure. In addition to the wholesale adoption of default settings, overly broad permissions or unsecured network communications can also open up significant vulnerabilities.
  • Neglecting regular security audits: Container configurations and security measures should be regularly reviewed. If you fail to audit these crucial operations components, you may overlook vulnerabilities and compliance issues.
  • Using outdated software: Container runtimes, just like any other software, need to be patched with security updates regularly. If you operate with outdated and unpatched container runtimes, applications, or dependencies, then you expose your systems to known vulnerabilities.
  • Poor secrets management: Improperly handling API keys or credentials, such as by embedding them directly in container images or configuration files, can lead to security breaches.

By proactively addressing these areas, your organization can significantly reduce its risk and maintain a robust security posture for its containerized applications.

Secure your containers with CrowdStrike

In this post, we’ve covered the essential aspects of container runtime security. We’ve explored key vulnerabilities and underscored the importance of implementing security best practices, such as the principle of least privilege, consistent updates, and continuous monitoring.

If you need confidence that your containers and container environments are secure, CrowdStrike Falcon® Cloud Security offers a comprehensive solution. It provides advanced protection capabilities designed specifically for container environments, such as runtime security and proactive threat intelligence. Access 1500+ out-of-the-box policies so you can easily validate your containers against expected code, checking for embedded secrets, vulnerabilities, misconfigurations, and CIS benchmark violations. This ensures that both container and container runtime environments remain protected against the latest security threats.

Learn more about how Falcon Cloud Security can bolster your container defenses by going through the self-paced interactive demo, or schedule a free Cloud Security Health Check to assess your cloud environment’s security.


Brett Shaw is a Sr. Product Marketing Manager at CrowdStrike responsible for Cloud Security and Cloud Partnerships. Brett has over 10 years of experience in IT and security helping professionals develop best practices with new technologies and industry trends. Brett previously held roles at Proofpoint, FireEye and VMware. He holds an MBA from Weber State University.