CVE-2015-8087 in NE20E-S
Summary
by MITRE
Huawei NE20E-S, NE40E-M, and NE40E-M2 routers with software before V800R007C10SPC100 and NE40E and NE80E routers with software before V800R007C00SPC100 allows remote attackers to send packets to other VPNs and conduct flooding attacks via a crafted MPLS forwarding packet, aka a "VPN routing and forwarding (VRF) hopping vulnerability."
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Analysis
by VulDB Data Team • 04/13/2018
The CVE-2015-8087 vulnerability represents a critical security flaw in Huawei's enterprise router lineup including the NE20E-S, NE40E-M, NE40E-M2, NE40E, and NE80E series. This vulnerability stems from improper handling of MPLS (Multiprotocol Label Switching) forwarding packets within the router's VRF (Virtual Routing and Forwarding) implementation, creating a pathway for unauthorized network access and traffic manipulation. The flaw affects specific software versions where the routers fail to properly validate MPLS packet headers, allowing malicious actors to exploit the routing table processing mechanisms to redirect traffic across different VPN instances.
The technical exploitation of this vulnerability occurs through the manipulation of MPLS label stacks in forwarding packets, where attackers craft specially formatted packets that bypass normal VRF isolation boundaries. When these crafted packets are processed by affected routers, the system incorrectly routes traffic to unintended VPN instances, effectively enabling VRF hopping attacks. This allows remote attackers to inject packets into other VPNs within the same router infrastructure, potentially accessing sensitive data flows or conducting distributed denial-of-service attacks by flooding multiple VPNs simultaneously. The vulnerability operates at the network layer, specifically within the MPLS forwarding plane, making it particularly dangerous as it can affect traffic across multiple isolated network segments.
The operational impact of CVE-2015-8087 extends beyond simple traffic redirection, creating significant security risks for enterprises relying on MPLS-based network infrastructures. Organizations may experience unauthorized data access across VPN boundaries, potential network disruption through flooding attacks, and compromise of network integrity. The vulnerability's remote exploitability means attackers can leverage this weakness from external network positions without requiring physical access or authentication credentials. This makes the attack surface particularly wide and the potential for damage substantial, especially in environments where multiple customer VPNs or organizational segments share the same router infrastructure, creating a direct pathway for cross-tenant data exposure and network interference.
Mitigation strategies for this vulnerability should focus on immediate software updates to the affected Huawei router versions, with patches addressing the MPLS packet validation mechanisms. Network administrators must implement strict ingress filtering on MPLS traffic, particularly at network boundaries where external packets enter the MPLS domain. The implementation of proper VRF isolation policies and monitoring of unusual traffic patterns can help detect exploitation attempts. Organizations should also consider network segmentation strategies that reduce the attack surface, and implement continuous monitoring of MPLS packet flows for anomalies that might indicate exploitation attempts. This vulnerability aligns with CWE-119, which addresses improper restriction of operations within a memory buffer, and maps to ATT&CK technique T1071.004 for application layer protocol: DNS, as exploitation may involve crafting DNS packets to traverse VRF boundaries, though the primary attack vector operates through MPLS packet manipulation rather than DNS protocols directly.
The vulnerability demonstrates the critical importance of proper label validation in MPLS networks, where insufficient input sanitization can lead to severe security consequences. Network security teams should conduct comprehensive vulnerability assessments of their MPLS infrastructure, particularly focusing on router models and software versions identified in the CVE. Regular security audits of routing protocols and MPLS implementations help identify similar weaknesses in network infrastructure, while maintaining updated security baselines ensures protection against evolving threat vectors targeting network infrastructure components.