CVE-2018-0102 in NX-OS
Summary
by MITRE
A vulnerability in the Pong tool of Cisco NX-OS Software could allow an unauthenticated, adjacent attacker to cause a reload of an affected device, resulting in a denial of service (DoS) condition. The vulnerability exists because the affected software attempts to free the same area of memory twice. An attacker could exploit this vulnerability by sending a pong request to an affected device from a location on the network that causes the pong reply packet to egress both a FabricPath port and a non-FabricPath port. An exploit could allow the attacker to cause a dual or quad supervisor virtual port-channel (vPC) to reload. This vulnerability affects the following products when running Cisco NX-OS Software Release 7.2(1)D(1), 7.2(2)D1(1), or 7.2(2)D1(2) with both the Pong and FabricPath features enabled and the FabricPath port is actively monitored via a SPAN session: Cisco Nexus 7000 Series Switches and Cisco Nexus 7700 Series Switches. Cisco Bug IDs: CSCuv98660.
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Analysis
by VulDB Data Team • 02/01/2021
The vulnerability identified as CVE-2018-0102 resides within Cisco NX-OS Software's Pong tool functionality, presenting a critical denial of service risk for network infrastructure devices. This weakness specifically impacts Cisco Nexus 7000 and 7700 Series Switches operating under particular software releases and configuration states. The vulnerability stems from improper memory management practices where the software attempts to free the same memory segment twice, creating a classic double-free error condition that fundamentally compromises system stability. Such memory corruption issues are categorized under CWE-415, representing an improper behavior in memory management that can lead to unpredictable system states and potential exploitation.
The attack vector for this vulnerability requires an unauthenticated adjacent attacker who can send specially crafted pong requests to the affected device. The exploitation mechanism is particularly sophisticated as it leverages the interaction between FabricPath and non-FabricPath network ports, requiring the attacker to position themselves within the same network segment to send packets that will cause the pong reply to egress through both types of ports simultaneously. This specific requirement demonstrates the network-level complexity needed to trigger the vulnerability, making it less accessible than remote attacks but still highly concerning for environments where physical network access is possible. The attack can cause complete reloads of dual or quad supervisor virtual port-channel configurations, effectively disrupting network connectivity and service availability.
The operational impact of this vulnerability extends beyond simple service disruption, as it can compromise the entire network infrastructure reliability. When a supervisor module reload occurs, it can result in temporary network outages, disruption of routing protocols, and potential loss of network monitoring data that flows through SPAN sessions. The affected configurations specifically require both Pong and FabricPath features to be enabled, along with active monitoring via SPAN sessions, indicating that organizations must maintain detailed awareness of their switch configurations to properly assess risk. This vulnerability aligns with ATT&CK technique T1499.004, which involves network disruption through service availability attacks, and demonstrates how memory corruption vulnerabilities can be weaponized for denial of service purposes.
Organizations should implement immediate mitigations including disabling unused FabricPath features when not required, implementing network segmentation to limit adjacent access, and ensuring proper software patching for the affected NX-OS releases. The vulnerability highlights the importance of maintaining current security patches and conducting regular configuration reviews to identify potentially vulnerable network elements. Cisco has provided specific bug fixes through CSCuv98660 that address this memory management issue by correcting the double-free condition in the Pong tool implementation. Network administrators should also consider implementing additional monitoring for unusual supervisor reload patterns and ensure that SPAN sessions are properly configured to avoid creating conditions that could facilitate this attack vector. The vulnerability serves as a reminder of the critical importance of memory safety in network infrastructure software, particularly in high-availability systems where a single memory corruption issue can result in complete service disruption.