CVE-2015-5434 in H3C Comware
Summary
by MITRE
HP H3C Comware 5 and 7 devices allow remote attackers to bypass intended access restrictions or cause a denial of service via "Virtual routing and forwarding (VRF) hopping."
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Analysis
by VulDB Data Team • 05/30/2018
The vulnerability identified as CVE-2015-5434 affects HP H3C Comware 5 and 7 network devices, representing a significant security flaw in virtual routing and forwarding implementations that can be exploited remotely. This vulnerability resides within the VRF handling mechanisms of these network appliances, which are commonly deployed in enterprise and service provider networks for traffic isolation and routing management. The affected devices implement VRF-based routing to separate network traffic for different tenants or business units, but the flaw allows unauthorized access to resources that should be isolated within specific routing contexts.
The technical flaw manifests through improper validation of VRF boundaries during packet processing and routing decisions, enabling attackers to traverse between different VRF instances without proper authorization. This occurs when the device fails to correctly enforce VRF isolation policies, allowing packets destined for one VRF to be processed through another VRF context. The vulnerability stems from inadequate input validation and insufficient access control enforcement mechanisms within the routing table processing logic, creating a pathway for malicious actors to access routing information or network resources that should remain isolated within specific virtual routing domains. This issue is classified under CWE-284, which addresses improper access control in software implementations, specifically targeting the violation of information flow control mechanisms.
The operational impact of this vulnerability extends beyond simple unauthorized access, as it can lead to complete network compromise and service disruption. Attackers can leverage VRF hopping to gain visibility into other network segments, potentially accessing sensitive data, conducting man-in-the-middle attacks, or disrupting network services through denial of service conditions. The ability to bypass access restrictions means that attackers can traverse network boundaries that were designed to maintain separation between different customer networks, tenant environments, or security domains. This vulnerability particularly affects multi-tenant network environments where multiple organizations or business units rely on VRF isolation for security and compliance requirements, creating potential for data leakage and cross-tenant attacks that violate fundamental network security principles.
Network administrators face significant challenges when addressing this vulnerability, as it requires careful consideration of the device's routing architecture and VRF configuration. The mitigation approach typically involves applying vendor security patches or firmware updates that correct the VRF boundary enforcement mechanisms, along with implementing additional access control measures such as enhanced ACLs and routing policy restrictions. Organizations should also consider implementing network segmentation strategies that reduce the attack surface and limit the potential impact of successful exploitation. The vulnerability highlights the importance of proper network design and access control implementation, particularly in environments where VRF-based isolation is critical for security compliance and data protection. This issue aligns with ATT&CK technique T1046, which covers network service scanning and access control bypass methods, demonstrating how vulnerabilities in routing protocols can enable broader network compromise and privilege escalation attacks.