CVE-2019-1606 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 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 user credentials to exploit this vulnerability. Nexus 3000, 3500, and Nexus 9000 Series Switches in Standalone NX-OS Mode are affected in versions prior to 7.0(3)I7(4).
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Analysis
by VulDB Data Team • 07/31/2023
The vulnerability identified as CVE-2019-1606 represents a critical command injection flaw within the command line interface of Cisco NX-OS Software affecting multiple switch series including Nexus 3000, 3500, and 9000 Series devices operating in standalone mode. This weakness stems from inadequate input validation mechanisms within the CLI parsing logic, creating a pathway for authenticated attackers to escalate privileges and execute unauthorized system commands. The vulnerability specifically targets the argument validation processes of certain CLI commands, where malicious input can be seamlessly incorporated into command parameters without proper sanitization or verification. The affected versions prior to 7.0(3)I7(4) demonstrate a persistent flaw in the software's security architecture that directly contradicts established principles of secure input handling and privilege separation. This issue fundamentally undermines the security boundaries of the network infrastructure devices, as it allows local authenticated users to bypass normal operational controls and gain elevated system access. The vulnerability's impact extends beyond simple command execution as it provides attackers with the ability to manipulate the underlying operating system, potentially leading to complete system compromise and unauthorized access to sensitive network data.
The technical exploitation of CVE-2019-1606 requires an attacker to possess valid user credentials, establishing it as a local privilege escalation vulnerability rather than a remote attack vector. However, this authentication requirement does not diminish the severity of the flaw, as it still enables attackers who have already gained access to legitimate user accounts to escalate their privileges and execute arbitrary code with elevated system permissions. The vulnerability operates through a classic command injection pattern where attacker-controlled input is passed directly to system commands without proper validation or sanitization. This flaw aligns with CWE-77 and CWE-88 categories, which specifically address command injection vulnerabilities and improper neutralization of special elements used in command execution contexts. The attack methodology involves crafting malicious command arguments that, when processed by the vulnerable CLI, are interpreted and executed by the underlying operating system shell. This exploitation technique leverages the fundamental weakness in input validation where the system fails to properly distinguish between legitimate user input and potentially malicious command sequences. The affected Nexus series switches maintain a consistent vulnerability profile across their product lines, indicating a systemic issue in the software development lifecycle that requires comprehensive remediation rather than isolated patching.
The operational impact of CVE-2019-1606 extends significantly beyond immediate system compromise, potentially enabling attackers to establish persistent access points within network infrastructure and exfiltrate sensitive operational data. Network administrators face a critical security gap where legitimate users can be exploited to gain unauthorized access to core network operations, potentially disrupting services and compromising network integrity. The vulnerability creates a persistent threat vector that could be leveraged for lateral movement within the network, as attackers with elevated privileges can manipulate network configurations and access other connected systems. Organizations running affected Cisco switches must consider the potential for data breaches, service disruptions, and unauthorized network modifications that could result from successful exploitation. The vulnerability also impacts compliance requirements for network security, as it represents a failure to maintain proper segregation of duties and privilege controls within network infrastructure devices. This flaw undermines the security posture of enterprise networks by creating an unauthorized escalation path that bypasses standard security controls and monitoring mechanisms, potentially allowing attackers to remain undetected while executing malicious activities.
Mitigation strategies for CVE-2019-1606 require immediate implementation of software updates to versions 7.0(3)I7(4) or later, which contain the necessary patches to address the input validation deficiencies. Network administrators should also implement comprehensive monitoring of CLI activities and user access patterns to detect potential exploitation attempts, as the vulnerability requires authenticated access but does not generate typical network-based attack signatures. The recommended approach includes enforcing strict access controls and privilege separation, limiting user accounts to minimum required permissions and implementing role-based access controls to reduce the potential impact of compromised credentials. Additionally, organizations should conduct thorough vulnerability assessments of their network infrastructure to identify other potential command injection vulnerabilities and ensure proper input validation across all network devices. The remediation process should include network segmentation to limit the scope of potential compromise and implementation of network access control lists to restrict CLI access to authorized personnel only. Regular security audits and penetration testing should be conducted to verify the effectiveness of implemented controls and identify additional security gaps that may exist within the network infrastructure. Organizations should also consider implementing security information and event management systems to detect anomalous command execution patterns that could indicate exploitation attempts, as this vulnerability represents a significant threat to network security and requires proactive defense measures to prevent successful exploitation.