CVE-2017-5936 in Nova-LXD
Summary
by MITRE
OpenStack Nova-LXD before 13.1.1 uses the wrong name for the veth pairs when applying Neutron security group rules for instances, which allows remote attackers to bypass intended security restrictions.
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Analysis
by VulDB Data Team • 08/25/2024
The vulnerability described in CVE-2017-5936 represents a critical flaw in OpenStack Nova-LXD integration that undermines network security controls through improper handling of virtual ethernet pair naming conventions. This issue affects versions prior to 13.1.1 of the Nova-LXD component, which serves as the container orchestration layer for OpenStack deployments using LXD container technology. The flaw specifically manifests when applying Neutron security group rules to instances, creating a scenario where network isolation mechanisms can be circumvented through manipulation of virtual network interfaces.
The technical root cause stems from the incorrect naming of virtual ethernet pairs within the LXD container environment, which directly impacts how Neutron security groups are enforced. When Nova-LXD creates network interfaces for container instances, it assigns veth pair names that do not align with the expected naming conventions used by Neutron's security group enforcement mechanisms. This misalignment creates a gap in the network security pipeline where traffic can bypass the intended filtering rules that should be applied to container instances. The vulnerability operates at the intersection of container networking and virtualization security controls, exploiting a fundamental mismatch in interface management between the container orchestration layer and the network security enforcement layer.
From an operational perspective, this vulnerability enables remote attackers to execute unauthorized network traffic flows that should have been restricted by security group policies. An attacker can leverage this flaw to gain access to services or resources that are normally isolated from their network segment, effectively breaking the network segmentation that security groups are designed to enforce. The impact extends beyond simple bypass of firewall rules to potentially allow lateral movement within cloud environments, privilege escalation through service access, and unauthorized data exfiltration. This vulnerability directly violates the principle of least privilege and network isolation that are fundamental to cloud security architectures.
The security implications of CVE-2017-5936 align with CWE-284, which addresses improper access control in network security contexts, and can be mapped to ATT&CK technique T1046 for network service scanning and T1071 for application layer protocol usage. Organizations utilizing OpenStack deployments with LXD containers face significant risk of unauthorized network access, particularly in multi-tenant environments where proper network isolation is critical. The vulnerability demonstrates the complexity of securing containerized environments within cloud infrastructures, where interactions between different software layers can create unexpected security gaps.
Mitigation strategies for this vulnerability require immediate patching of Nova-LXD components to version 13.1.1 or later, which contains the corrected veth pair naming implementation. Network administrators should also implement additional monitoring for anomalous network traffic patterns that might indicate exploitation attempts, particularly around the interfaces where security group enforcement should be active. Organizations should conduct comprehensive audits of their container networking configurations to identify any instances where similar naming convention issues might exist in other components. Additionally, implementing network segmentation controls at multiple layers, including hypervisor-level and container-level security, can provide defense-in-depth measures that reduce the overall impact of such vulnerabilities. The vulnerability highlights the importance of maintaining strict adherence to networking standards and conventions when integrating different cloud components, as even seemingly minor implementation details can create significant security weaknesses.