CVE-2017-12335 in NX-OS
Summary
by MITRE
A vulnerability in the CLI of Cisco NX-OS System Software could allow an authenticated, local attacker to perform a command injection attack. The vulnerability is due to insufficient input validation of command arguments. An attacker could exploit this vulnerability by injecting crafted command arguments into a vulnerable CLI command and gain unauthorized access to the underlying operating system of the device. An exploit could allow the attacker to execute arbitrary commands at the user's privilege level. On products that support multiple virtual device contexts (VDCs), this vulnerability could allow an attacker to execute commands at the user's privilege level outside the user's environment. This vulnerability affects the following products running Cisco NX-OS System Software: Multilayer Director Switches, Nexus 2000 Series Fabric Extenders, Nexus 3000 Series Switches, Nexus 5000 Series Switches, Nexus 5500 Platform Switches, Nexus 5600 Platform Switches, Nexus 6000 Series Switches, Nexus 7000 Series Switches, Nexus 7700 Series Switches, Nexus 9000 Series Switches in standalone NX-OS mode, Nexus 9500 R-Series Line Cards and Fabric Modules, Unified Computing System Manager. Cisco Bug IDs: CSCvf14923, CSCvf14926, CSCvg04095.
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Analysis
by VulDB Data Team • 01/25/2021
The vulnerability identified as CVE-2017-12335 represents a critical command injection flaw within the command line interface of Cisco NX-OS System Software, classified under CWE-77 and mapping to ATT&CK technique T1059.001 for command and scripting interpreter. This security weakness stems from inadequate input validation mechanisms that fail to properly sanitize command arguments passed to vulnerable CLI commands, creating an exploitable pathway for authenticated local attackers to execute arbitrary code on affected network devices. The flaw specifically impacts the underlying operating system of Cisco switches and routers, potentially allowing privilege escalation to user-level execution capabilities.
The technical implementation of this vulnerability occurs when legitimate users with local access attempt to execute CLI commands that do not properly validate or escape input parameters. Attackers can craft malicious command arguments that bypass input sanitization controls, enabling them to inject additional commands that execute within the same execution context as the legitimate user. This injection mechanism operates at the user privilege level, meaning that successful exploitation allows attackers to perform actions that would normally be restricted to authorized users. The vulnerability is particularly concerning because it exists within the CLI interface itself, which is a fundamental management component that administrators rely upon for device configuration and monitoring.
The operational impact of this vulnerability extends beyond simple command execution, as it can be leveraged to compromise the entire network infrastructure managed by affected Cisco devices. In environments where multiple virtual device contexts (VDCs) are implemented, the flaw becomes even more dangerous since attackers can potentially execute commands outside their designated VDC environment, thereby breaking the isolation boundaries that are critical for network security segmentation. This cross-context execution capability significantly amplifies the potential damage, as attackers could access configurations, data, or commands from other virtual devices within the same physical hardware platform. The vulnerability affects a broad range of Cisco networking equipment including high-end switches and fabric extenders across multiple product lines, making it a widespread concern for enterprise network security.
Mitigation strategies for CVE-2017-12335 should focus on immediate software updates and configuration hardening measures. Cisco released patches addressing this vulnerability through multiple bug fixes including CSCvf14923, CSCvf14926, and CSCvg04095, which implement proper input validation and command argument sanitization. Network administrators should prioritize applying these security updates across all affected devices and VDC environments to prevent exploitation. Additional protective measures include implementing strict access controls for CLI access, monitoring command execution logs for suspicious patterns, and establishing network segmentation strategies that limit the potential impact of successful exploitation. The vulnerability highlights the importance of input validation in security-critical applications and demonstrates how seemingly minor flaws in command processing can lead to significant security breaches in network infrastructure devices.