CVE-2019-1776 in NX-OS
Summary
by MITRE
A vulnerability in the CLI of Cisco NX-OS Software could allow an authenticated, local attacker to execute arbitrary commands on the underlying Linux operating system with a privilege level of root. The vulnerability is due to insufficient validation of arguments passed to a specific CLI command on the affected device. 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 Linux 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-2019-1776 represents a critical privilege escalation flaw within Cisco NX-OS Software command line interface. This security weakness exists in the authentication and input validation mechanisms of the network operating system, specifically targeting the CLI command processing functionality. The vulnerability stems from inadequate argument validation that fails to properly sanitize user inputs before processing them within the underlying Linux operating system environment. The flaw affects devices running Cisco NX-OS Software where the CLI interface processes commands without sufficient input filtering, creating a pathway for malicious code execution. This type of vulnerability falls under CWE-20, which describes improper input validation, and aligns with ATT&CK technique T1068, which covers local privilege escalation through command injection.
The technical exploitation of this vulnerability requires an authenticated attacker with administrator-level credentials to execute malicious payloads. Once authenticated, the attacker can leverage the insufficient argument validation by crafting specific input parameters that bypass normal command parsing and directly invoke system-level commands. The vulnerability allows execution of arbitrary commands with root privileges, effectively compromising the entire underlying Linux operating system. This privilege escalation occurs because the CLI command processing does not adequately validate the arguments passed to specific commands, permitting malicious input to be interpreted and executed as system commands rather than treated as simple parameters. The attack vector demonstrates how improper input handling in network device management interfaces can create severe security implications, as the attacker essentially gains complete control over the device's operating system through legitimate administrative access points.
The operational impact of this vulnerability extends beyond simple command execution, as it fundamentally undermines the security posture of affected network infrastructure. Organizations relying on Cisco NX-OS devices face potential complete system compromise, data exfiltration, and disruption of network services. The vulnerability's exploitation requires only valid administrative credentials, making it particularly dangerous as it can be leveraged by insider threats or compromised accounts. Network administrators may experience unauthorized access to sensitive network configurations, monitoring capabilities, and system resources that should remain protected. The root-level access granted through this vulnerability enables attackers to modify system files, install backdoors, alter network routing, and potentially use the compromised device as a pivot point for attacking other systems within the network infrastructure. This represents a significant risk to enterprise security operations and network integrity.
Mitigation strategies for CVE-2019-1776 focus on both immediate patching and operational security improvements. Cisco released software updates addressing this vulnerability, and organizations should prioritize applying these patches to all affected devices. Network segmentation and least privilege access controls can reduce the attack surface by limiting administrative access to only necessary personnel. Implementing strict monitoring of CLI command execution and input patterns can help detect anomalous behavior indicative of exploitation attempts. Regular security assessments of network device configurations and access controls should include verification of input validation mechanisms. Organizations should also consider implementing additional security layers such as secure shell (ssh) key authentication, multi-factor authentication, and network access control systems to reduce the likelihood of successful exploitation. The vulnerability highlights the importance of comprehensive input validation across all network device interfaces and demonstrates how seemingly minor implementation flaws can result in critical security breaches.