CVE-2019-11252 in kube-controller-manager
Summary
by MITRE
The Kubernetes kube-controller-manager in versions v1.0-v1.17 is vulnerable to a credential leakage via error messages in mount failure logs and events for AzureFile and CephFS volumes.
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Analysis
by VulDB Data Team • 11/05/2020
The vulnerability CVE-2019-11252 affects the Kubernetes kube-controller-manager component across versions 1.0 through 1.17, specifically exposing sensitive credential information through error logging mechanisms when volume mount operations fail. This issue stems from the improper handling of authentication credentials within error messages generated during AzureFile and CephFS volume operations, creating a significant security risk for containerized environments that rely on these storage backends. The flaw represents a direct violation of information exposure principles and falls under the CWE-209 category of "Information Exposure Through an Error Message" within the Common Weakness Enumeration framework.
When Kubernetes attempts to mount AzureFile or CephFS volumes and encounters authentication failures, the system logs detailed error messages that inadvertently include credential data such as storage account keys, access tokens, or authentication secrets. These logs are typically written to the controller manager's output streams and may be accessible to unauthorized users with sufficient privileges to view system logs or event logs. The exposure occurs because the logging mechanism does not sanitize or redact sensitive information before including it in error contexts, creating a pathway for attackers to obtain authentication credentials that could be used to access cloud storage resources or compromise additional systems within the same storage account.
The operational impact of this vulnerability extends beyond simple credential leakage, as it enables attackers to potentially gain unauthorized access to cloud storage resources, leading to data breaches, storage account compromise, and potential lateral movement within cloud environments. The vulnerability affects organizations using Kubernetes clusters with AzureFile or CephFS persistent volumes, making it particularly relevant for cloud-native applications that depend on these storage backends. The exposure of credentials through error messages creates a persistent risk that remains active until the affected versions are patched, as attackers can continuously harvest credentials from log files or event streams.
Mitigation strategies for CVE-2019-11252 require immediate patching of affected Kubernetes versions to the latest stable releases that contain the fix for credential sanitization in error messages. Organizations should also implement comprehensive log monitoring and filtering mechanisms to prevent sensitive data from being written to system logs, including the deployment of log sanitization tools and the configuration of log retention policies that exclude credential information. Additionally, security teams should conduct regular audits of system logs and implement automated alerting for suspicious credential exposure patterns. The fix typically involves modifying the kube-controller-manager's error handling logic to sanitize credential information before logging, ensuring that authentication secrets are never included in error messages or events. This vulnerability aligns with ATT&CK technique T1552.001 for "Unsecured Credentials" and demonstrates the critical importance of proper input validation and output sanitization in cloud-native security architectures. Organizations should also consider implementing network segmentation and access controls to limit who can view system logs and events, reducing the attack surface for credential harvesting.