CVE-2015-5303 in OpenStack
Summary
by MITRE
The TripleO Heat templates (tripleo-heat-templates), when deployed via the commandline interface, allow remote attackers to spoof OpenStack Networking metadata requests by leveraging knowledge of the default value of the NeutronMetadataProxySharedSecret parameter.
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Analysis
by VulDB Data Team • 07/13/2022
The vulnerability identified as CVE-2015-5303 affects the TripleO Heat templates ecosystem, which serves as a critical deployment framework for OpenStack cloud environments. This issue specifically manifests when these templates are executed through the command line interface, creating a pathway for remote attackers to exploit weaknesses in the metadata service architecture. The vulnerability stems from the default configuration values that are pre-set within the deployment templates, making it particularly dangerous as it requires minimal reconnaissance to exploit. The affected component operates within the OpenStack Networking (Neutron) subsystem, where metadata requests are processed through a proxy mechanism that relies on shared secrets for authentication and validation.
The technical flaw resides in the NeutronMetadataProxySharedSecret parameter which is set to a predictable default value within the TripleO Heat templates. When attackers gain knowledge of this default shared secret, they can craft malicious metadata requests that appear legitimate to the Neutron metadata proxy service. This spoofing capability allows unauthorized entities to bypass normal authentication mechanisms and potentially access or manipulate metadata services that should be restricted to authorized instances. The vulnerability operates at the network protocol level where metadata requests are typically handled by the nova metadata service, which validates requests through the shared secret mechanism. This represents a classic credential exposure issue where default configuration values become attack vectors.
The operational impact of this vulnerability extends beyond simple information disclosure, as it enables attackers to potentially manipulate instance metadata, access sensitive configuration data, and potentially escalate privileges within the OpenStack environment. The attack surface is particularly concerning because TripleO Heat templates are commonly used for production cloud deployments, meaning that exploitation could compromise entire cloud infrastructures. An attacker could use this vulnerability to retrieve instance user data, network configuration details, or other sensitive metadata that might contain credentials or configuration parameters. This type of attack aligns with the ATT&CK technique of credential access and privilege escalation, specifically targeting the cloud infrastructure's metadata service. The vulnerability also represents a failure in the principle of least privilege, as default configurations should never expose system components to unauthorized access.
Mitigation strategies for CVE-2015-5303 require immediate action to address the default configuration issue. Organizations must ensure that the NeutronMetadataProxySharedSecret parameter is explicitly configured with strong, unique values rather than relying on default settings. This involves modifying the TripleO Heat templates to use randomized secrets during deployment or implementing automated secret generation processes. Security best practices dictate that all shared secrets should be generated using cryptographically secure random number generators and should be unique per deployment. The vulnerability also highlights the importance of configuration management and the need for regular security audits of deployment templates. Organizations should implement automated scanning tools to identify and remediate default configuration values in their OpenStack deployments. This aligns with CWE-798, which specifically addresses the use of hard-coded credentials, and represents a critical security control that should be part of any comprehensive OpenStack security posture. Regular security training for deployment personnel is also essential to ensure they understand the implications of default configuration values and the importance of proper secret management in cloud environments.