CVE-2018-0306 in NX-OS
Summary
by MITRE
A vulnerability in the CLI parser of Cisco NX-OS Software could allow an authenticated, local attacker to perform a command-injection attack on an affected device. The vulnerability is due to insufficient input validation of command arguments. An attacker could exploit this vulnerability by injecting malicious command arguments into a vulnerable CLI command. A successful exploit could allow the attacker to execute arbitrary commands with root privileges on the affected device. Note: This vulnerability requires that any feature license is uploaded to the device. The vulnerability does not require that the license be used. This vulnerability affects MDS 9000 Series Multilayer Switches, Nexus 1000V Series Switches, Nexus 1100 Series Cloud Services Platforms, Nexus 2000 Series Fabric Extenders, Nexus 3000 Series Switches, Nexus 3500 Platform Switches, Nexus 3600 Platform 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. Cisco Bug IDs: CSCve51693, CSCve91634, CSCve91659, CSCve91663.
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Analysis
by VulDB Data Team • 03/28/2023
This vulnerability resides within the command-line interface parser of Cisco NX-OS software, representing a critical security flaw that enables authenticated local attackers to execute command injection attacks on affected network devices. The vulnerability stems from inadequate input validation mechanisms that fail to properly sanitize command arguments passed to CLI functions. Attackers can exploit this weakness by crafting malicious command arguments that bypass normal input filtering, allowing them to inject arbitrary commands into the system. The flaw specifically affects multiple Cisco product lines including various Nexus series switches and MDS 9000 series multilayer switches, indicating a widespread impact across Cisco's enterprise networking portfolio. The vulnerability requires only authentication to the device and does not necessitate active usage of any licensed features, making it particularly dangerous as it can be exploited regardless of whether specific licensing is actively engaged. This represents a classic command injection vulnerability that aligns with CWE-77 and follows the ATT&CK technique T1059.001 for command and scripting interpreter, where adversaries leverage legitimate system interfaces to execute malicious code.
The operational impact of this vulnerability extends beyond simple privilege escalation, as successful exploitation grants attackers root privileges on the affected devices, effectively providing complete control over the network infrastructure. This level of access enables attackers to modify device configurations, establish persistent backdoors, exfiltrate sensitive network information, or disrupt network services entirely. The attack vector is particularly concerning because it operates at the local administrative level, meaning that any authenticated user with access to the CLI can potentially exploit this vulnerability. The requirement for a license upload to trigger the vulnerability, while seemingly restrictive, actually makes the attack more insidious as it can be triggered by any user who has access to upload licensing features, potentially including system administrators or authorized personnel. The widespread nature of affected platforms means that organizations with diverse Cisco networking equipment across their infrastructure face a common vulnerability that could be exploited to compromise their entire network security posture.
Organizations should implement immediate mitigations including restricting local administrative access to devices, implementing strict access controls for CLI functionality, and monitoring for suspicious command execution patterns. Network segmentation and least privilege principles should be enforced to limit the potential impact of exploitation. Cisco has released patches addressing this vulnerability through multiple bug fixes including CSCve51693, CSCve91634, CSCve91659, and CSCve91663, which should be deployed immediately across all affected platforms. The vulnerability demonstrates the importance of input validation in system interfaces and highlights the need for comprehensive security testing of CLI parsers in network operating systems. Organizations should also consider implementing additional monitoring solutions to detect anomalous command execution patterns that might indicate exploitation attempts, particularly focusing on unusual command sequences or privilege escalation activities. Regular security assessments of network device configurations and access controls should be performed to identify and remediate similar vulnerabilities that could provide attackers with unauthorized access to critical network infrastructure components.