CVE-2015-6277 in NX-OS
Summary
by MITRE
The ARP implementation in Cisco NX-OS on Nexus 1000V devices for VMware vSphere 5.2(1)SV3(1.4), Nexus 3000 devices 7.3(0)ZD(0.47), Nexus 4000 devices 4.1(2)E1, Nexus 9000 devices 7.3(0)ZD(0.61), and MDS 9000 devices 7.0(0)HSK(0.353) and SAN-OS NX-OS on MDS 9000 devices 7.0(0)HSK(0.353) allows remote attackers to cause a denial of service (ARP process restart) via crafted packet-header fields, aka Bug ID CSCut25292.
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Analysis
by VulDB Data Team • 06/14/2022
The vulnerability described in CVE-2015-6277 represents a critical flaw in the Address Resolution Protocol implementation within Cisco NX-OS operating systems running on various enterprise networking devices. This issue affects a wide range of Cisco hardware including Nexus 1000V virtual switches for VMware environments, Nexus 3000 and 4000 series switches, Nexus 9000 series routers, and MDS 9000 storage area network devices. The vulnerability specifically targets the ARP processing functionality that handles the mapping between IP addresses and MAC addresses, which is fundamental to network communication. The affected versions demonstrate that Cisco's implementation contains a parsing flaw in how it handles incoming packet headers, particularly those containing malformed or crafted ARP request and reply messages that exploit the protocol's structure.
The technical nature of this vulnerability stems from insufficient input validation within the ARP processing module of the NX-OS operating system. When the system receives specially crafted packet-header fields that contain malformed data or unexpected values in the ARP packet structure, the implementation fails to properly validate these inputs before processing them. This lack of proper sanitization and validation causes the ARP process to crash or restart unexpectedly, leading to a denial of service condition that disrupts network communications. The flaw operates at the network protocol level where the system's ARP daemon or process becomes unstable when encountering these malformed packets, triggering a restart that temporarily removes the device from active network operations.
The operational impact of this vulnerability extends beyond simple service disruption as it can compromise network availability and reliability across enterprise environments. Organizations relying on Cisco Nexus and MDS devices for their networking infrastructure face significant risks when this vulnerability is exploited, particularly in mission-critical environments where network uptime is essential. The denial of service affects not only the specific device experiencing the restart but can also cause cascading effects throughout the network topology, especially in virtualized environments where Nexus 1000V devices are commonly deployed. Network administrators may experience disruptions in communication between virtual machines, storage connections, and other network services that depend on stable ARP resolution mechanisms. The vulnerability's remote exploitability means that attackers can trigger the denial of service from outside the network perimeter without requiring physical access or authentication credentials.
Mitigation strategies for this vulnerability require immediate attention from network administrators and security teams. The primary recommendation involves applying the relevant security patches provided by Cisco through their official security advisories, specifically addressing the bug ID CSCut25292. Organizations should prioritize updating their affected devices to patched versions of NX-OS, ensuring that all Nexus 1000V, Nexus 3000, Nexus 4000, Nexus 9000, and MDS 9000 devices are upgraded to versions that contain the necessary fixes. Network segmentation and access controls should be implemented to limit exposure, while monitoring systems should be enhanced to detect unusual ARP traffic patterns that might indicate exploitation attempts. The vulnerability aligns with CWE-129, which describes improper validation of input boundaries, and represents a classic example of how protocol implementation flaws can lead to denial of service conditions. From an attack framework perspective, this vulnerability fits within the ATT&CK technique T1499.004 for Network Denial of Service, demonstrating how seemingly minor protocol parsing issues can have significant operational impacts on enterprise network infrastructure and requiring careful remediation strategies to maintain network availability and security posture.