CVE-2018-1085 in openshift-ansible
Summary
by MITRE
openshift-ansible before versions 3.9.23, 3.7.46 deploys a misconfigured etcd file that causes the SSL client certificate authentication to be disabled. Quotations around the values of ETCD_CLIENT_CERT_AUTH and ETCD_PEER_CLIENT_CERT_AUTH in etcd.conf result in etcd being configured to allow remote users to connect without any authentication if they can access the etcd server bound to the network on the master nodes. An attacker could use this flaw to read and modify all the data about the Openshift cluster in the etcd datastore, potentially adding another compute node, or bringing down the entire cluster.
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Analysis
by VulDB Data Team • 03/27/2023
The vulnerability identified as CVE-2018-1085 represents a critical authentication flaw in the openshift-ansible deployment tooling that affects versions prior to 3.9.23 and 3.7.46. This issue stems from improper configuration of the etcd datastore component which serves as the backbone for storing all cluster state information in OpenShift environments. The flaw specifically impacts the master nodes where etcd is deployed, creating a pathway for unauthorized access that bypasses the intended security controls. The vulnerability manifests through the incorrect handling of environment variable values in the etcd.conf configuration file, where quotation marks around boolean values inadvertently disable crucial client certificate authentication mechanisms.
The technical root cause of this vulnerability lies in the improper parsing and handling of configuration parameters within the deployment automation scripts. When the ETCD_CLIENT_CERT_AUTH and ETCD_PEER_CLIENT_CERT_AUTH environment variables are wrapped in quotation marks within the etcd.conf file, the etcd service interprets these values as literal strings rather than boolean flags. This misinterpretation results in the authentication system being effectively disabled, allowing any remote user who can establish network connectivity to the etcd server to access the cluster data without proper authentication. The vulnerability is classified under CWE-284 Access Control Bypass, which specifically addresses situations where improper access control mechanisms allow unauthorized access to protected resources.
The operational impact of this vulnerability is severe and far-reaching within OpenShift cluster environments. An attacker who gains network access to the master node's etcd service can execute arbitrary read and write operations against the entire cluster state database, potentially leading to complete cluster compromise. This includes the ability to inject malicious configuration data, modify cluster topology, add unauthorized compute nodes, or even delete critical cluster resources. The attack surface is particularly concerning because the vulnerability affects the fundamental data store that maintains all cluster information, including pod states, service configurations, and security policies. This aligns with ATT&CK technique T1078 Valid Accounts, as the compromised etcd access provides a privileged foothold that can be leveraged for further lateral movement and persistence within the cluster.
The security implications extend beyond simple data access, as the compromised etcd datastore can be used to manipulate the entire cluster's operational state. Attackers could potentially disrupt cluster operations by modifying service endpoints, altering network policies, or injecting malicious configurations that could affect multiple workloads. The vulnerability also creates opportunities for data exfiltration, as etcd contains sensitive information about all cluster resources, including secrets, configurations, and operational metadata. Organizations deploying OpenShift clusters without updating to the patched versions remain exposed to this vulnerability, which can be exploited by attackers with minimal network access to the master nodes. The remediation requires updating the openshift-ansible tooling to versions that properly handle the etcd configuration parameters without introducing authentication bypasses, ensuring that client certificate authentication remains enabled and functional.
This vulnerability demonstrates the critical importance of proper configuration management in container orchestration platforms and highlights how seemingly minor automation script issues can create severe security implications. The flaw underscores the need for comprehensive security testing of deployment automation tools, particularly those handling critical infrastructure components like etcd. Organizations should implement regular security assessments of their deployment toolchains and maintain up-to-date configurations to prevent such authentication bypass scenarios. The incident also emphasizes the necessity of network segmentation and access controls to limit exposure of critical components like etcd servers to untrusted networks, providing an additional layer of defense against exploitation of such configuration flaws.