CVE-2020-3415 in NX-OS
Summary
by MITRE
A vulnerability in the Data Management Engine (DME) of Cisco NX-OS Software could allow an unauthenticated, adjacent attacker to execute arbitrary code with administrative privileges or cause a denial of service (DoS) condition on an affected device. The vulnerability is due to insufficient input validation. An attacker could exploit this vulnerability by sending a crafted Cisco Discovery Protocol packet to a Layer 2-adjacent affected device. A successful exploit could allow the attacker to execute arbitrary code with administrative privileges or cause the Cisco Discovery Protocol process to crash and restart multiple times, causing the affected device to reload and resulting in a DoS condition. Note: Cisco Discovery Protocol is a Layer 2 protocol. To exploit this vulnerability, an attacker must be in the same broadcast domain as the affected device (Layer 2 adjacent). Exploitation of this vulnerability also requires jumbo frames to be enabled on the interface that receives the crafted Cisco Discovery Protocol packets on the affected device.
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Analysis
by VulDB Data Team • 11/11/2020
The vulnerability identified as CVE-2020-3415 resides within the Data Management Engine component of Cisco NX-OS Software, representing a critical security flaw that undermines the integrity and availability of network infrastructure devices. This weakness manifests as insufficient input validation mechanisms within the Cisco Discovery Protocol (CDP) processing functionality, creating an exploitable entry point for malicious actors who possess physical or logical proximity to the targeted system. The vulnerability's classification aligns with CWE-20, which describes improper input validation as a fundamental weakness in software design that permits malicious data to be processed without adequate sanitization or verification. The attack vector specifically targets Layer 2 adjacent networks where attackers can directly communicate with network devices through the same broadcast domain, making this vulnerability particularly concerning for enterprise environments where physical security controls may be insufficient.
The technical exploitation of CVE-2020-3415 requires an attacker to craft and transmit specially formatted Cisco Discovery Protocol packets to a vulnerable device, leveraging the inherent trust relationships established by Layer 2 protocols. This attack methodology falls under the ATT&CK framework's technique T1059.007, which encompasses the execution of code through network protocols and services. The vulnerability's exploitation path demands that jumbo frames be enabled on the receiving interface, indicating that network administrators must be aware of both the protocol configuration and the physical network topology to properly assess their exposure. The combination of Layer 2 adjacency requirements and the specific jumbo frame dependency creates a narrow but potentially devastating attack window where unauthorized users can gain administrative control or disrupt service availability.
The operational impact of this vulnerability extends beyond simple privilege escalation, as it can result in complete system compromise or sustained denial of service conditions that can severely impact business continuity. When successfully exploited, the vulnerability allows attackers to execute arbitrary code with administrative privileges, effectively granting them complete control over the targeted device, which aligns with ATT&CK technique T1068 that covers local privilege escalation. The potential for causing service disruption through repeated crashes and device reloads represents a significant availability threat, particularly in mission-critical network environments where device reliability is paramount. Organizations running affected Cisco NX-OS software versions face the risk of unauthorized access to sensitive network infrastructure, potential data exfiltration, and disruption of critical network services that depend on these devices for operation.
Mitigation strategies for CVE-2020-3415 should focus on both immediate protective measures and long-term architectural improvements to reduce the attack surface. Network administrators should implement the latest Cisco security patches and updates that address the input validation deficiencies in the Data Management Engine, while simultaneously reviewing and restricting the use of jumbo frames on network interfaces where CDP is processed. The implementation of network segmentation and access control lists can help limit the broadcast domain exposure, reducing the likelihood of successful exploitation by limiting an attacker's ability to reach vulnerable devices through Layer 2 adjacency. Additionally, monitoring network traffic for anomalous CDP packet patterns and implementing intrusion detection systems can provide early warning capabilities for potential exploitation attempts, while compliance with security standards such as NIST SP 800-53 and ISO/IEC 27001 can help establish comprehensive security frameworks that address both the technical vulnerability and operational security requirements.