As containers continue to have more layers of abstraction, they have introduced greater complexity that calls for specific tools to successfully monitor and protect these environments. This increasing complexity has guaranteed that simple perimeter defense approaches are now ineffective and obsolete.
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What is Container Security?
Container security refers to tools, processes, and policies that aim to enhance the security competence of containers so that the applications they house may run free of incidents and vulnerabilities. A typical containerized architecture has three elements; the container engine, orchestrators, and managed Kubernetes services.
The container engine is based on an operating system where the kernel supports many isolated instances. Each instance is a container or virtualization engine where developers create virtual hosts with isolated resources. Applications, configurations, and more dependencies can be deployed within containers to reduce application management overhead. These engines include Docker, Containerd, and Windows Containers.
Container orchestrators enable developers to deploy many containers and manage them at scale through container clusters. Container orchestration makes it possible to manage application lifecycles or ecosystems with many containers. Orchestrators can automatically deploy containers depending on policies. They can also restrict container-container and container-to-external-system access to enhance security. Orchestrators include Kubernetes and OpenShift.
Managed Kubernetes services
Managed Kubernetes services provide an additional level of management atop of orchestrators. Organizations can provide container images and automatically create Kubernetes clusters that are manageable through the CLI, APIs, or web-based consoles. Managed Kubernetes services include Google Kubernetes Engine (GKE) and Amazon Elastic Kubernetes Service (EKS).
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Containers vs Virtual Machines
Containers often offer delicate isolation between the host and other containers. They also provide a weaker security boundary compared to virtual machines. On the other hand, virtual machines enforce total isolation from the host operating system and other virtual machines. A strong security boundary is critical with tasks such as hosting different applications on the same server or cluster.
A container contains an application and all the functions required to run it, making it specific to a single application. This ensures that containers are lightweight, making them simple to deploy across different environments. As such, containers are a better choice for cloud-native application development.
A virtual machine can run substantially more operations and tasks than a container since it has its own operating system. However, this complicates its ability to run an entire application as it leads to complex and bloated virtual machines. This also introduces latency and makes VMs less reliable for cloud-native development.
Application scaling and deployment
Although both virtual machines and containers let developers improve the memory and CPU usage of physical machines, containers go the extra mile to enable microservice architectures. These architectures allow a more granular approach to the deployment and scaling of application components.
Benefits of Container Security
Building blocks for immutable infrastructure. In line with immutable infrastructure architectures, container components are completely replaced, rather than modified, when they require updating. This lowers the risk of introducing security vulnerabilities.
Quick updates. Containerized applications can be easily updated. It is also possible to update specific microservices without impacting others in an application.
Single source of truth for application development. A container has all dependencies linked with an application, allowing an application to run smoothly and consistently across different environments.
No friction. Moving application code all through testing to production is a frictional process. Having application code in containers ensures that this friction is averted.
Challenges of Container Security
Container complexity. Containers can have many rapidly changing layers and components, inadvertently introducing unnecessary complexity. As dynamic as they are, the complexity of containerized applications may make them strenuous to manage, which impacts security.
Ecosystem complexity. If the tools used for building, managing, and deploying containers are from different sources or repositories, it increases the complexity of the ecosystem. This places greater responsibility on security teams to ensure that these diverse components are secure.
No isolation. Unlike with virtual machines, when a threat actor compromises a container, they can gain access to others on the same host.
Kubernetes lacks built-in security. Kubernetes in particular helps create a secure cluster by providing access controls and features. However, it lacks built-in security to secure containers.
Approaching Container Security
Secure your runtime
Container runtime security is the process of securing applications from newly discovered vulnerabilities in running containers. As it involves thoroughly examining all the activities within the container application environment like container and host activity analysis and monitoring network protocols and payloads, container runtime security becomes a challenge to secure.
Traditional security solutions become ineffective as they lack the visibility required to secure containers in production. Most of these solutions are effective at network endpoints and perimeters but cannot examine network traffic inside containers. They are also often siloed and often offer a choice between workload or network security, which represents a disparity with modern container environments.
Using vulnerability scanning tools does not guarantee container runtime security either as they only identify known vulnerabilities. As such, these tools will be ineffective in the event of zero day attacks. However, securing the network through deep network visibility and protection measures greatly improves runtime security.
Ultimately, a holistic approach boosts the effectiveness of container runtime security. Cloud-native environments enable the merging of network and workload security to provide full visibility into container environments. A unified view helps teams to formulate baselines for their container environments to determine what counts as a secure container environment, making it easier to flag anomalies and prevent attacks.
Secure your registry
A container registry presents a unified means of storage and distribution of application images. Organizations today can store tens of thousands of images in their registries. As registries are key to the operation of a containerized environment, they have to be secured.
Combining container registry and Kubernetes gives users the ability to execute a set of security and quality standards for their containers before and during redeployment into their environments. Containers should be scanned to identify known vulnerabilities and to ensure they meet both security and development baselines.
The registry should run on a hardened system. Organizations can lock down the server hosting the registry. The registry can also run on a reputable cloud service; however, a role-based access control model should be considered.
Secure your orchestrator
Container orchestration security involves imposing the correct access control measures to mitigate the risks introduced by over-privileged accounts, attacks on the network, and undesired lateral movement. One of the security concerns of container orchestration is that a vulnerability in the host operating system or kernel could be exploited in a container as it shares the host operating system and host kernel.
A rogue process or a vulnerability in the orchestrator, or a running container image can all provide a point of entry to an attacker. The complexity added by orchestration automation can expand the attack surface by encouraging misconfigurations that overprovision access. To minimize these concerns, identity access management (IAM) can be leveraged in cloud security with a least privileged access model. This involves having Docker and Kubernetes activity whitelisted to allow security and infrastructure teams to only execute commands based on the correct roles.
Enterprises should also protect their pod-to-pod communications and prevent threat actors from laterally traversing their environments. Kubernetes offers the ability to implement various operational and security controls to help organizations satisfy their risk tolerance.
Secure your host operating system
Protecting your operating system is the first step of securing the host as the operating system that hosts your container is a crucial security layer. A compromised host environment can compromise the rest of your stack. Protecting the host starts with your choice of an operating system. Distributed operating systems enhanced to run containers are worth considering.
You can set up a layer of monitoring tools to ensure your host runs as expected. Intrusion detection systems used with application control tools can be effective in these environments. You can also harden your hosts based on CIS benchmarks.
Container Security Tools to Consider
When selecting container security tools, organizations should implement tools that cover container scanning and monitoring, policy engines, and container firewalls.
Containers should constantly be scanned for vulnerabilities. This should happen before being deployed and after replacement in a production environment. Failure to scan containers may result in vulnerabilities being used as building blocks of an application. Developers can also inadvertently add a library to a container with vulnerabilities.
Organizations should use container scanning tools that maintain container image trust. These tools should be able to align to an image scanning workflow to make sure that they examine the reliability and security of containers used as building blocks.
A key measure that enterprises should consider to maintain container security is implementing tools that continuously monitor their registries. These monitoring tools should enable ITOps and cybersecurity teams to implement time-series stamps to containers to ensure that there is visibility into their containerized environments since developers constantly rip and replace containers.
Organizations should have a framework to define and ensure policies are enforced and always maintained across a container application environment. The tools that organizations should consider should help cybersecurity teams define access control policies for any microservices.
Container firewalls examine and secure all traffic flowing through a container. Network security teams benefit from the visibility and management features container firewalls give them over their Kubernetes environments.
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