CVE-2018-1267 in Cloud Foundry Silk CNI Plugin
Summary
by MITRE
Cloud Foundry Silk CNI plugin, versions prior to 0.2.0, contains an improper access control vulnerability. If the platform is configured with an application security group (ASG) that overlaps with the Silk overlay network, any applications can reach any other application on the network regardless of the configured routing policies.
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Analysis
by VulDB Data Team • 01/17/2020
The Cloud Foundry Silk CNI plugin vulnerability represents a critical improper access control flaw that undermines network security within containerized environments. This vulnerability affects versions prior to 0.2.0 and specifically targets the application security group functionality that is fundamental to Cloud Foundry's network isolation mechanisms. The flaw exists at the intersection of network policy enforcement and overlay network implementation, creating a scenario where security boundaries become effectively meaningless. When application security groups are configured to overlap with the Silk overlay network, the vulnerability allows for complete bypass of intended network segmentation, enabling arbitrary communication between applications that should remain isolated.
The technical root cause of this vulnerability stems from inadequate validation of network policy enforcement within the CNI plugin's network configuration process. The Silk CNI plugin fails to properly enforce the boundaries defined by application security groups when these groups overlap with the overlay network space. This misconfiguration creates a pathway where network traffic can traverse from any application to any other application within the same network segment, regardless of the security policies that should restrict such communication. The vulnerability manifests as a failure in the plugin's ability to distinguish between legitimate network operations and unauthorized cross-application access, effectively neutralizing the security controls that administrators have implemented.
The operational impact of this vulnerability extends far beyond simple network connectivity issues, representing a significant compromise to application security and data integrity. Attackers who can exploit this vulnerability gain the ability to perform lateral movement within the network, potentially accessing sensitive application data, escalating privileges, or disrupting services. The vulnerability particularly affects multi-tenant environments where different applications or organizations share the same infrastructure, as it allows unauthorized access to resources that should be isolated. This creates a substantial risk for compliance violations, as the breach of network segmentation can lead to unauthorized data access that may violate regulatory requirements such as those outlined in pci dss, hipaa, or gdpr frameworks.
Mitigation strategies for this vulnerability require immediate patching of the Silk CNI plugin to version 0.2.0 or later, which contains the necessary fixes to properly enforce network policy boundaries. Organizations should also implement additional monitoring and logging of network traffic between applications to detect any unauthorized communication patterns that might indicate exploitation attempts. Network administrators should conduct thorough reviews of existing application security group configurations to ensure proper isolation of applications and eliminate overlapping network spaces. The remediation process should include validating that network policies are correctly enforced and that the CNI plugin properly respects the security boundaries defined by application security groups. This vulnerability aligns with CWE-284, which addresses improper access control, and represents a specific implementation weakness in network policy enforcement that could be categorized under ATT&CK technique T1046 for network service scanning and T1071 for application layer protocol communication.