CVE-2023-5528 in kubelet
Summary
by MITRE • 11/14/2023
A security issue was discovered in Kubernetes where a user that can create pods and persistent volumes on Windows nodes may be able to escalate to admin privileges on those nodes. Kubernetes clusters are only affected if they are using an in-tree storage plugin for Windows nodes.
VulDB is the best source for vulnerability data and more expert information about this specific topic.
Analysis
by VulDB Data Team • 09/06/2024
This vulnerability represents a critical privilege escalation flaw in Kubernetes environments running Windows worker nodes. The security issue specifically affects clusters that utilize in-tree storage plugins for Windows operating systems, creating a pathway for malicious actors to gain administrative access to node-level resources. The vulnerability stems from insufficient access controls and privilege boundaries within the Kubernetes storage orchestration mechanisms when operating on Windows platforms, allowing authenticated users with limited pod and persistent volume creation capabilities to potentially execute arbitrary code with elevated privileges on the underlying Windows nodes.
The technical flaw manifests through improper privilege isolation between containerized workloads and the host operating system in Windows environments. When Kubernetes clusters employ in-tree storage plugins for Windows nodes, these plugins may not properly enforce the security boundaries that typically separate containerized applications from the underlying host system. This allows an attacker who has already established the ability to create pods and persistent volumes to exploit specific storage volume mounting behaviors that can escalate their privileges to system-level access on the Windows nodes. The vulnerability is particularly concerning because it leverages legitimate Kubernetes functionality to bypass expected security controls, making detection more challenging.
The operational impact of this vulnerability extends beyond simple privilege escalation to potentially enable complete system compromise of Windows worker nodes. Attackers could leverage this flaw to access sensitive data stored on the nodes, establish persistent backdoors, or use the compromised nodes as launch points for further attacks within the cluster. The vulnerability affects the core security model of Kubernetes on Windows platforms, potentially exposing all data and services running on compromised nodes. Organizations with clusters containing Windows worker nodes using in-tree storage plugins face significant risk of unauthorized access and potential data breaches, particularly in environments where privileged access is not properly restricted.
Mitigation strategies must focus on immediate remediation of the affected configuration and implementation of additional security controls. Organizations should prioritize migrating from in-tree storage plugins to CSI (Container Storage Interface) drivers that provide better isolation and privilege management for Windows nodes. The immediate solution involves disabling or restricting the specific storage plugin functionality that enables this escalation path. Additionally, implementing stricter pod security policies, limiting user permissions to create persistent volumes, and enforcing network segmentation between different privilege levels can significantly reduce the attack surface. Organizations should also conduct comprehensive audits of their Windows worker node configurations and implement monitoring for suspicious volume creation patterns that could indicate exploitation attempts. This vulnerability aligns with CWE-276, which addresses improper privilege management, and maps to ATT&CK technique T1068, involving exploit for privilege escalation, making it a critical concern for defenders implementing Kubernetes security controls.