CVE-2023-6476 in cri-o
Summary
by MITRE • 01/10/2024
A flaw was found in CRI-O that involves an experimental annotation leading to a container being unconfined. This may allow a pod to specify and get any amount of memory/cpu, circumventing the kubernetes scheduler and potentially resulting in a denial of service in the node.
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Analysis
by VulDB Data Team • 01/28/2024
The vulnerability identified as CVE-2023-6476 resides within the Container Runtime Interface implementation known as CRI-O, which serves as a crucial component in Kubernetes environments for container management. This flaw specifically involves an experimental annotation mechanism that when improperly configured or exploited, can result in containers operating outside of the intended security boundaries and resource constraints. The issue manifests through a configuration pathway that allows pods to bypass the standard Kubernetes resource management controls, effectively removing the confinement mechanisms that typically regulate computational resources.
The technical implementation of this vulnerability stems from how CRI-O processes experimental annotations that are designed to provide additional container capabilities. When these annotations are improperly handled or when they contain maliciously crafted values, the container runtime can be coerced into operating without the typical resource limits that Kubernetes enforces. This experimental feature, intended to provide enhanced functionality, becomes a vector for privilege escalation and resource abuse when not properly secured. The flaw directly impacts the container runtime's ability to enforce resource quotas and scheduling policies, creating a scenario where containers can consume unlimited CPU cycles and memory resources.
From an operational perspective, this vulnerability presents a significant risk to cluster stability and resource availability. When exploited, the affected containers can consume all available node resources, leading to denial of service conditions that impact not only the compromised pod but potentially other workloads running on the same node. The bypass of Kubernetes scheduler functionality means that the cluster's resource management algorithms become ineffective, allowing resource exhaustion that can cascade across multiple applications and services. This represents a critical failure in the principle of least privilege and resource isolation that Kubernetes is designed to enforce, potentially enabling attackers to disrupt service availability or cause system-wide performance degradation.
The security implications extend beyond simple resource exhaustion to include potential privilege escalation and system compromise. According to CWE classification, this vulnerability aligns with CWE-269: "Improper Privilege Management" and CWE-400: "Uncontrolled Resource Consumption", as it allows for the unauthorized consumption of system resources while potentially bypassing privilege controls. From the ATT&CK framework perspective, this vulnerability maps to T1499.004: "Cloud Service Configuration Misalignment" and T1566.001: "Phishing via Service Provider" as it represents a misconfiguration that can be exploited to gain unauthorized access to system resources. Organizations should implement strict annotation validation policies, disable experimental features in production environments, and enforce comprehensive monitoring of resource consumption patterns to detect potential exploitation attempts. The recommended mitigations include disabling experimental annotations, implementing strict admission control policies, and ensuring that all container runtime configurations adhere to security best practices as outlined in the Kubernetes security guidelines and the Center for Internet Security (CIS) benchmarks.