CVE-2017-12351 in NX-OS
Summary
by MITRE
A vulnerability in the guest shell feature of Cisco NX-OS System Software could allow an authenticated, local attacker to read and send packets outside the scope of the guest shell container. An attacker would need valid administrator credentials to perform this attack. The vulnerability is due to insufficient internal security measures in the guest shell feature. An attacker could exploit this vulnerability by sending or receiving packets on the device-internal network outside of the guest shell container, aka "Unauthorized Internal Interface Access." This vulnerability affects the following products running Cisco NX-OS System Software: Nexus 3000 Series Switches, Nexus 9000 Series Switches in standalone NX-OS mode, Nexus 9500 R-Series Line Cards and Fabric Modules. Cisco Bug IDs: CSCvf33038.
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Analysis
by VulDB Data Team • 01/25/2021
The vulnerability identified as CVE-2017-12351 resides within the guest shell feature of Cisco NX-OS System Software, representing a critical security flaw that undermines the isolation mechanisms designed to protect network infrastructure components. This weakness specifically targets the containerized environment that Cisco provides for authorized administrators to execute commands and applications, creating an unintended pathway for privilege escalation and unauthorized network access. The vulnerability stems from inadequate internal security controls that fail to properly enforce boundaries between the guest shell container and the underlying network device infrastructure, effectively allowing malicious actors to bypass containment measures that should restrict network interface access.
The technical exploitation of this vulnerability requires an authenticated administrator account, making it a local privilege escalation issue rather than a remote attack vector. However, the implications are severe as the attacker can leverage their administrative credentials to access network interfaces that should remain isolated within the guest shell environment. This unauthorized access enables the execution of packet transmission and reception activities on device-internal networks, essentially allowing attackers to communicate beyond the intended scope of the guest shell container. The flaw manifests as a failure in network interface isolation, where the guest shell feature does not properly restrict access to internal network interfaces that are typically protected from external interference.
The operational impact of this vulnerability extends beyond simple unauthorized access, as it creates potential for significant network disruption and data exfiltration. Attackers could potentially intercept sensitive network traffic, manipulate internal communications, or use the compromised device as a pivot point for further attacks within the network infrastructure. The vulnerability affects critical Cisco networking equipment including Nexus 3000 Series Switches, Nexus 9000 Series Switches operating in standalone NX-OS mode, and Nexus 9500 R-Series Line Cards and Fabric Modules, all of which form the backbone of many enterprise and data center networks. This widespread impact means that organizations with these devices could face substantial security risks if the vulnerability remains unpatched.
From a cybersecurity perspective, this vulnerability aligns with CWE-276, which addresses improper privileges and access control mechanisms, and demonstrates characteristics consistent with ATT&CK technique T1068, involving local privilege escalation through system configuration weaknesses. The flaw represents a fundamental breakdown in the principle of least privilege, where administrative access should not automatically grant unrestricted network interface capabilities. Organizations affected by this vulnerability should prioritize immediate patch deployment through official Cisco security advisories, while implementing network segmentation measures to limit the potential impact of any successful exploitation attempts. The vulnerability also highlights the importance of regular security assessments of containerized environments and the need for robust isolation mechanisms in network operating systems that handle sensitive infrastructure functions.