Container Runtime Security

Containers are the cornerstone of cloud-native infrastructure. They’re a game-changer for scalability and speed, but their rise in popularity has created a container security challenge for modern enterprises. For example, a recent security flaw in AWS Elastic Container Registry (ECR) could have enabled a threat actor to inject malicious code into other users’ container images.

Below, we take a closer look at what container runtime security is, five runtime container security threats enterprises need to know, and key best practices and tools to improve overall workload security posture.

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What is Container Runtime Security?

Container runtime security is the set of tools and practices that protect containers from instantiation to termination. It is a subset of container security and workload protection that deals with securing everything that happens with a container from instantiation to termination. For example, container runtime security deals with scanning running containers for vulnerabilities, but scanning of plaintext source code. That means vulnerability scanners are an example of runtime container security tools, but a SAST scanner is not.

However, container runtime security isn’t an isolated concept. Beyond the containers themselves, securing source code, Kubernetes (K8s), and infrastructure as code (IaC) are important aspects of providing defense in depth that set enterprise container runtime security efforts up for success.

Top 5 Container Runtime Security Threats Enterprises Need to Know

The five container runtime security threats below can create significant risk for enterprises that run container workloads.

Unauthorized container deployments: Deploy Container (T1610) from the MITRE ATT&CK’s list of techniques used by enterprise adversaries is a great example of a container security threat. With this technique attackers deploy a container — for example using Docker’s create and start commands — that bypass security controls and enable exploits.
Misconfigurations and insecure configurations: Insecure configurations are one of the most common container security risks. For example, a container that exposes unnecessary network ports or hardcodes API keys are examples of Insecure configurations.
Container images with malware: This risk is especially prevalent when enterprises use public container registries. Threat actors can embed malware to container images and then post them to public registries for enterprises to use.
Privilege escalation attacks: There are a variety of privilege escalation attacks that can lead to an attacker gaining root access to a container or the underlying host. These attacks often begin by exploiting an insecure configuration or existing vulnerability.
Unpatched vulnerabilities: Unmatched vulnerabilities, like an access control bug in an application, provide threat actors with an easier path to compromise a container.

How to Find and Remediate Container Security Runtime Risks

Consistent with the concept of shift left security, early detection is key to effective container runtime security. Ideally, enterprises should detect threats before container instantiation even occurs.

However, that isn’t always practical. That’s where runtime scanning and threat detection come into play. Once a threat is detected, the ideal case is that it is automatically remediated in a way that intelligently limits false positives. For the remaining cases, security professionals should be quickly alerted to take corrective action.

5 Runtime Container Security Best Practices

The five best practices below can help enterprises effectively find and remediate container runtime security risks.

Only run trusted container images: Only running trusted container images from secure repositories limits the risk of instantiating an insecure image.
Implement continuous vulnerability scanning: Point-in-time security checks are useful, but not enough. To stay ahead of evolving threats, enterprises should continuously scan workloads for real-time threat detection.
Run containers with low-privilege users: Enterprises should avoid running containers as the root user or with the Docker –privileged flag. Generally, containers shouldn’t need root access to the host environment, so using root violates the principle of least privilege. Similarly, the –privileged flag bypasses important security controls.
Don’t enable writable file systems: Containers are usually intended to be ephemeral. Enabling writable file systems creates the potential for attackers to write and execute malicious code.
Centralize and automate visibility and policy enforcement: Manually monitoring and securing containers isn’t scalable. It’s also prone to human error. As much as practical, enterprises should leverage tools that centralize and automate visibility into container security and policies.

Effective Container Runtime Security Requires a Holistic Approach

Container runtime security doesn’t exist in a vacuum. For example, IaC security and container runtime security go hand-in-hand. To maintain a strong security posture, enterprises need to implement holistic solutions that integrate security throughout the software development lifecycle (SDLC). That means tools that enable enterprise wide visibility and security across clouds and provide security wherever enterprises run containers are essential to modern workload and runtime protection.