CVE-2014-3295 in NX-OS
Summary
by MITRE
The HSRP implementation in Cisco NX-OS 6.2(2a) and earlier allows remote attackers to bypass authentication and cause a denial of service (group-member state modification and traffic blackholing) via malformed HSRP packets, aka Bug ID CSCup11309.
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Analysis
by VulDB Data Team • 06/22/2021
The vulnerability described in CVE-2014-3295 represents a critical flaw in the Hot Standby Router Protocol implementation within Cisco NX-OS software versions 6.2(2a) and earlier. This issue specifically targets the HSRP protocol which is widely used for providing redundant routing paths in network environments, ensuring high availability and fault tolerance. The vulnerability allows remote attackers to exploit weaknesses in the packet processing logic that governs how HSRP messages are validated and processed, creating a significant security risk for networks relying on this protocol for redundancy management.
The technical flaw manifests through improper validation of HSRP packet structures, enabling attackers to craft malformed packets that can bypass the authentication mechanisms inherent to HSRP. This vulnerability operates at the network protocol level and specifically affects the group-member state modification capabilities within the HSRP implementation. When exploited, these malformed packets can cause the affected router to alter its HSRP group membership state, potentially leading to the creation of a false standby router state. This manipulation allows attackers to effectively take control of the HSRP group membership, which can result in traffic blackholing where network traffic is redirected through compromised paths or completely dropped from the network.
The operational impact of this vulnerability extends beyond simple denial of service conditions, as it can completely compromise the integrity of the HSRP protocol implementation and potentially lead to complete network disruption. Attackers can leverage this vulnerability to cause legitimate network traffic to be routed through compromised paths or to be completely blackholed, effectively creating a man-in-the-middle scenario where network communications are intercepted or disrupted. The vulnerability affects the core redundancy mechanisms that organizations rely on for maintaining network availability, making it particularly dangerous in mission-critical environments where network uptime is essential. This flaw can be exploited remotely without requiring authentication credentials, making it particularly attractive to attackers who wish to disrupt network services.
This vulnerability aligns with CWE-225, which describes weaknesses in input validation, and maps to ATT&CK technique T1071.004 for application layer protocol manipulation. The attack surface is particularly concerning as it affects the fundamental network protocol implementations that are critical to enterprise network operations, potentially allowing attackers to create persistent network disruption conditions that can be difficult to detect and remediate. Organizations should implement immediate mitigations including software upgrades to patched versions of NX-OS, network segmentation to limit attack surface, and monitoring of HSRP packet flows to detect anomalous behavior patterns. The vulnerability demonstrates the importance of proper protocol implementation validation and the need for robust input sanitization in network infrastructure software to prevent exploitation of fundamental protocol mechanisms that are designed to provide network resilience and redundancy.