CVE-2019-12274 in Rancher
Summary
by MITRE
In Rancher 1 and 2 through 2.2.3, unprivileged users (if allowed to deploy nodes) can gain admin access to the Rancher management plane because node driver options intentionally allow posting certain data to the cloud. The problem is that a user could choose to post a sensitive file such as /root/.kube/config or /var/lib/rancher/management-state/cred/kubeconfig-system.yaml.
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Analysis
by VulDB Data Team • 06/20/2020
This vulnerability exists in Rancher management platforms version 1 and 2 through 2.2.3 where unprivileged users who are permitted to deploy nodes can escalate their privileges to administrative access. The flaw stems from the node driver configuration that intentionally permits posting specific data to cloud environments, creating an attack vector that adversaries can exploit to gain elevated privileges. The vulnerability is classified under CWE-269 Improper Privilege Management, which specifically addresses when a system grants more privileges than intended to an actor. The security issue manifests when users can leverage node deployment capabilities to upload sensitive configuration files that contain administrative credentials.
The technical implementation of this vulnerability involves the cloud driver options that allow users to specify data that gets posted to cloud environments during node creation. When a user with limited privileges deploys a node, they can manipulate the node driver configuration to include sensitive files such as /root/.kube/config or /var/lib/rancher/management-state/cred/kubeconfig-system.yaml. These files contain administrative credentials that grant full access to the Rancher management plane. The attack leverages the principle of least privilege violation where user-controlled node deployment processes inadvertently provide access to critical system files that should remain restricted to administrators. This represents a critical privilege escalation vulnerability that directly violates the security principle of access control enforcement.
The operational impact of this vulnerability is severe as it allows any user with node deployment permissions to gain full administrative control over the Rancher management plane. This means that an attacker could potentially compromise the entire container orchestration environment, access all managed clusters, and perform arbitrary operations including creating new clusters, modifying existing configurations, and accessing sensitive data. The vulnerability affects the core security model of Rancher by allowing unauthorized privilege escalation through legitimate node deployment workflows. This could result in complete system compromise, data breaches, and unauthorized access to containerized applications and infrastructure managed by the Rancher platform. The attack requires minimal sophistication and can be executed through standard node deployment procedures, making it particularly dangerous in environments where node deployment permissions are broadly distributed.
Mitigation strategies for this vulnerability should focus on implementing strict access controls and privilege management within the Rancher platform. Organizations should immediately upgrade to Rancher versions that have addressed this vulnerability, specifically versions beyond 2.2.3 where proper privilege controls have been implemented. The recommended approach involves enforcing stricter validation of node driver options to prevent the inclusion of sensitive files during node deployment processes. Additionally, implementing network segmentation and access controls can limit which users can perform node deployments, thereby reducing the attack surface. The mitigation aligns with ATT&CK technique T1078 Valid Accounts which emphasizes the importance of proper account and privilege management to prevent unauthorized access. Organizations should also implement monitoring and alerting mechanisms to detect suspicious node deployment activities that may indicate privilege escalation attempts. System administrators should conduct regular audits of user permissions and node deployment configurations to ensure that only authorized personnel can access sensitive system files. The vulnerability demonstrates the critical importance of proper input validation and privilege enforcement in container management platforms, and organizations should review their overall security posture to prevent similar issues in other components of their infrastructure.