Kubernetes Cluster Enumeration via Audit Logs

Attackers are increasingly targeting Kubernetes environments to gain unauthorized access and extract sensitive information. This activity often begins with enumeration and reconnaissance to map out the cluster’s configuration, identify potential vulnerabilities, and locate valuable secrets. This involves the use of standard command-line tools and specialized Kubernetes utilities. Audit logs provide a valuable record of these enumeration attempts, particularly API requests containing shell commands, file transfer utilities, or tools like Rakkess and TruffleHog. This activity is typically aimed at reconnaissance, secret harvesting, or code execution within the cluster. Detecting these patterns in audit logs is critical for identifying and responding to potential breaches.

Attack Chain

1. Attacker gains initial access to a system with Kubernetes API access, potentially through compromised credentials or a vulnerable application.
2. The attacker authenticates to the Kubernetes API server.
3. The attacker sends a request to the Kubernetes API to execute a shell within a pod, such as /bin/bash or /bin/sh, potentially URL-encoded.
4. The attacker uses kubectl within a pod to gather information about cluster resources, such as pods, services, and deployments.
5. The attacker attempts to download tools like curl or wget into a pod to facilitate further reconnaissance or lateral movement.
6. The attacker uses tools like Rakkess to enumerate role-based access control (RBAC) permissions to identify potential privilege escalation paths.
7. The attacker deploys TruffleHog to scan pod environments for exposed secrets, such as API keys and passwords.
8. The attacker exfiltrates gathered information and secrets or uses the gained access for lateral movement within the cluster or connected networks.

Impact

Successful enumeration of a Kubernetes cluster can provide attackers with detailed information about the cluster’s architecture, deployed applications, and security configurations. This allows attackers to identify vulnerabilities, escalate privileges, and gain access to sensitive data, such as API keys, passwords, and other secrets. This can lead to data breaches, service disruptions, and compromised infrastructure. The impact can range from a limited data exposure to a full-scale compromise of the entire Kubernetes environment and connected cloud resources.

Recommendation

• Deploy the “Kubernetes Potential Enumeration Activity” Sigma rule to your SIEM to detect suspicious API requests containing shell commands, file transfer utilities, or specialized tools (Sigma rule).
• Investigate any alerts triggered by the Sigma rule to determine the scope and impact of the potential enumeration activity.
• Review and harden RBAC configurations to minimize the potential for privilege escalation (attack.t1609).
• Implement strict network segmentation to limit lateral movement within the cluster and connected networks.
• Regularly scan pods for exposed secrets using dedicated secret scanning tools and enforce secure secret management practices.
• Monitor Kubernetes audit logs for unusual or unauthorized API activity (logsource: kubernetes, service: audit).