CVE-2019-1791 in NX-OS
Summary
by MITRE
A vulnerability in the CLI of Cisco NX-OS Software could allow an authenticated, local attacker with administrator credentials to execute arbitrary commands with elevated privileges on the underlying operating system of an affected device. The vulnerability is due to insufficient validation of arguments passed to certain CLI commands. An attacker could exploit this vulnerability by including malicious input as the argument of an affected command. A successful exploit could allow the attacker to execute arbitrary commands on the underlying operating system with elevated privileges. An attacker would need valid administrator credentials to exploit this vulnerability.
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Analysis
by VulDB Data Team • 09/21/2023
The vulnerability identified as CVE-2019-1791 represents a critical privilege escalation flaw within Cisco NX-OS Software command-line interface implementation. This security weakness resides in the insufficient input validation mechanisms that govern how command arguments are processed within the device's operational environment. The vulnerability specifically affects the CLI subsystem where certain commands fail to properly validate user-supplied parameters, creating an avenue for malicious input injection that can bypass normal security controls. The affected Cisco NX-OS software versions typically include various network switching and routing platforms that utilize this command processing framework, making the vulnerability pervasive across multiple network infrastructure components.
The technical exploitation of this vulnerability requires an authenticated attacker possessing administrator-level credentials, which significantly reduces the attack surface compared to remote exploits but does not eliminate the severity of the issue. When an attacker issues a specially crafted command with malicious arguments, the insufficient validation allows the system to process these inputs without proper sanitization or verification. This processing flaw enables the execution of arbitrary operating system commands with the elevated privileges of the administrative account, effectively granting the attacker complete control over the underlying operating system. The vulnerability falls under the CWE-20 category of "Improper Input Validation" and specifically relates to CWE-78 "Improper Neutralization of Special Elements used in an OS Command" when the malicious input leads to command injection scenarios.
The operational impact of this vulnerability extends far beyond simple privilege escalation, as it fundamentally compromises the security posture of affected network devices. Once exploited, an attacker gains unrestricted access to the operating system level of the device, enabling them to modify system configurations, install malicious software, access sensitive network data, and potentially use the compromised device as a pivot point for further attacks within the network infrastructure. The elevated privileges obtained through this vulnerability allow for complete system compromise, making it a highly attractive target for threat actors seeking to establish persistent access within enterprise networks. This vulnerability directly aligns with ATT&CK technique T1068 "Exploitation for Privilege Escalation" and T1566 "Phishing for Information" when considering how attackers might obtain the necessary administrator credentials.
Mitigation strategies for CVE-2019-1791 require immediate implementation of Cisco's security advisories and software updates that address the input validation deficiencies in the affected CLI commands. Network administrators should prioritize applying the relevant security patches and firmware updates provided by Cisco to remediate the vulnerability. Additionally, implementing strict access controls and monitoring for unusual CLI command patterns can help detect potential exploitation attempts. The principle of least privilege should be enforced by limiting administrative access to only authorized personnel and implementing multi-factor authentication for administrator accounts. Network segmentation and monitoring solutions should be deployed to detect anomalous behavior that might indicate exploitation attempts, particularly focusing on command execution patterns that deviate from normal operational procedures. Organizations should also conduct comprehensive vulnerability assessments to identify all affected devices and ensure that proper network access controls are in place to minimize the potential impact of any successful exploitation attempts.