CVE-2016-7404 in OpenStack Magnum
Summary
by MITRE
OpenStack Magnum passes OpenStack credentials into the Heat templates creating its instances. While these should just be used for retrieving the instances' SSL certificates, they allow full API access, though and can be used to perform any API operation the user is authorized to perform.
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Analysis
by VulDB Data Team • 10/07/2023
OpenStack Magnum represents a container orchestration service that leverages Heat templates for instance provisioning within cloud environments. The vulnerability described in CVE-2016-7404 stems from a critical design flaw in how Magnum handles authentication credentials when executing Heat templates. Specifically, the system passes full OpenStack credentials including user authentication tokens and access keys directly into the Heat template parameters rather than limiting them to the minimal required scope for certificate retrieval operations. This architectural oversight creates a severe privilege escalation risk where the credentials embedded within the Heat templates can be exploited to perform any API operation that the original user has authorization rights to execute.
The technical implementation of this vulnerability involves the improper handling of credential scope within the Magnum service's template processing pipeline. When Heat templates are generated and executed by Magnum, the system indiscriminately includes all available authentication credentials in the template parameters without proper sanitization or scope limitation. This practice violates fundamental security principles of least privilege and privilege separation, allowing the template execution environment to gain access to the full breadth of the user's API permissions. The flaw exists at the interface between Magnum's credential management system and the Heat orchestration engine, creating an attack surface where malicious actors can leverage the embedded credentials for unauthorized access to cloud resources.
The operational impact of this vulnerability extends beyond simple credential exposure, creating significant risks for cloud infrastructure security. Attackers who can access or manipulate Heat templates can potentially escalate privileges to perform operations such as creating new instances, modifying existing resources, accessing confidential data, or even deleting critical infrastructure components. This vulnerability undermines the security boundaries that should exist between different user roles and system components, effectively allowing unauthorized access to cloud resources through the template execution process. The risk is particularly severe in multi-tenant environments where users may have varying levels of access permissions, as the embedded credentials could enable privilege escalation across different user contexts.
This vulnerability aligns with CWE-284, which addresses improper access control, and reflects patterns commonly seen in privilege escalation attacks within cloud orchestration systems. The flaw demonstrates a clear violation of the principle of least privilege, where excessive permissions are granted to template execution environments. From an ATT&CK framework perspective, this vulnerability maps to privilege escalation techniques and credential access phases, specifically targeting the use of legitimate credentials for unauthorized access. Organizations should implement immediate mitigations including credential scope limitation, template parameter sanitization, and regular auditing of template execution environments. The recommended approach involves modifying the Magnum service to generate Heat templates with minimal required credentials or implementing a dedicated credential broker system that provides scoped access tokens specifically for certificate retrieval operations rather than exposing full user credentials. Additionally, organizations should enforce strict template validation policies and consider implementing automated monitoring for credential exposure within template parameters to detect and prevent similar vulnerabilities in other orchestration services.