Types of Logs

Types of Logs in Kubernetes

Understanding the different types of logs generated within a Kubernetes environment is essential for effective threat hunting and security monitoring. Kubernetes, as a complex and dynamic system, produces logs at various levels, each providing unique insights into the cluster's operation and security posture. This section explores the primary types of logs in Kubernetes, their significance, and how they can be leveraged in a cybersecurity context.

Application Logs

Application logs are the most common type of logs generated in a Kubernetes environment. These logs capture the output of applications running within containers and can include anything from simple status messages to detailed error reports.

• Purpose: Application logs provide visibility into the behavior and performance of the software running in your pods. They are critical for debugging issues, monitoring application health, and identifying anomalies that could indicate a security incident.

• Use Cases:

  • Error Detection: Identifying application crashes, exceptions, or unexpected behavior.

  • Monitoring: Tracking application performance metrics, such as response times and request rates.

  • Threat Hunting: Detecting suspicious activity within the application, such as unauthorized access attempts or unusual data processing patterns.

• How to Access: Application logs can be accessed using the kubectl logs command, which retrieves logs from a specific container within a pod. For example:

  kubectl logs <pod-name> -c <container-name>

Node and System Logs

Node and system logs are generated by the underlying infrastructure that supports Kubernetes, including the operating system, container runtime, and other system components. These logs provide insights into the health and performance of the nodes themselves.

• Purpose: Node and system logs are essential for monitoring the health of the Kubernetes infrastructure. They help in identifying issues at the node level, such as resource exhaustion, network problems, or hardware failures.

• Use Cases:

  • Infrastructure Monitoring: Detecting and diagnosing issues with nodes, such as CPU or memory saturation.

  • Security Monitoring: Identifying unauthorized access to nodes or suspicious system-level activities, such as unexpected process creation.

  • Threat Hunting: Investigating potential node compromises, such as container escapes or privilege escalations.

• How to Access: Node logs are typically stored in the /var/log/ directory on each node. Key logs include:

  • kubelet.log: Logs generated by the Kubelet, the primary agent running on each node.

  • containerd.log or docker.log: Logs from the container runtime responsible for running containers.

Kubernetes Control Plane Logs

The Kubernetes control plane is responsible for managing the overall state of the cluster, including scheduling pods, maintaining desired state, and responding to API requests. Control plane logs are generated by the components that make up the Kubernetes control plane, such as the API server, scheduler, and controller manager.

• Purpose: Control plane logs provide critical insights into the operations of the Kubernetes cluster itself. They are essential for understanding how the cluster is being managed and for diagnosing issues related to pod scheduling, configuration changes, and API requests.

• Use Cases:

  • Cluster Management: Monitoring the health and performance of the control plane components.

  • Security Auditing: Tracking API requests, configuration changes, and other administrative actions.

  • Threat Hunting: Detecting unauthorized access or modifications to the cluster, such as suspicious API calls or changes to critical resources.

• How to Access: Control plane logs are typically accessible through the logging mechanisms provided by the cloud provider or managed Kubernetes service. For self-managed clusters, these logs are often stored on the master node. Key logs include:

  • kube-apiserver.log: Logs from the Kubernetes API server, which processes all API requests.

  • kube-scheduler.log: Logs from the Kubernetes scheduler, which assigns pods to nodes.

  • kube-controller-manager.log: Logs from the controller manager, which maintains the desired state of the cluster.

Audit Logs

Audit logs are a specialized type of log that records all requests made to the Kubernetes API server, along with the outcomes of those requests. These logs are crucial for maintaining a security audit trail and are often required for compliance purposes.

• Purpose: Audit logs provide a comprehensive record of all actions taken within the Kubernetes cluster. This includes who made the request, what action was taken, and whether the action was successful. These logs are vital for detecting and investigating unauthorized access or changes to the cluster.

• Use Cases:

  • Security Auditing: Ensuring compliance with security policies and regulations by maintaining a detailed audit trail of API activity.

  • Forensic Analysis: Investigating security incidents by reconstructing the sequence of actions leading up to an event.

  • Threat Hunting: Identifying patterns of malicious activity, such as repeated failed login attempts or unauthorized modifications to critical resources.

• How to Access: Audit logs are generated by the Kubernetes API server and are typically stored in a file on the master node. The location and format of audit logs can be configured via the Kubernetes API server’s audit policy.

Network Logs

Network logs capture details about the network traffic within the Kubernetes cluster. These logs can provide insights into the communication between different components, such as pods, services, and external systems.

• Purpose: Network logs are essential for monitoring and securing the network communication within a Kubernetes cluster. They can help detect unauthorized access, lateral movement, and data exfiltration.

• Use Cases:

  • Network Security: Monitoring network traffic for unusual patterns or unauthorized access attempts.

  • Performance Monitoring: Identifying network bottlenecks or misconfigurations that affect application performance.

  • Threat Hunting: Detecting lateral movement by analyzing network connections between pods and nodes.

• How to Access: Network logs can be collected using network plugins (e.g., Calico, Cilium) or by integrating Kubernetes with network monitoring tools. Additionally, cloud providers may offer network logging features that capture traffic data.

Conclusion

Each type of log in Kubernetes serves a unique purpose and provides valuable information for maintaining the security and health of the cluster. As a cybersecurity threat hunter, understanding the different types of logs and how to access and analyze them is crucial for effective threat detection, incident response, and forensic analysis. The following modules will delve deeper into how to collect, manage, and analyze these logs to uncover potential security threats in your Kubernetes environment.