CVE-2019-1769 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 on the underlying Linux operating system of an attached line card with the 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 of an attached line card 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-2019-1769 represents a critical privilege escalation flaw within Cisco NX-OS Software that undermines the security boundaries between the network operating system and its underlying Linux environment. This weakness specifically affects the command-line interface implementation where insufficient input validation creates an attack surface that allows authenticated administrators to bypass normal security controls. The vulnerability exists in the manner in which the system processes command arguments, creating a path for malicious input to be executed with root privileges on line card components. The flaw demonstrates a classic command injection vulnerability pattern that has been documented in various security frameworks including CWE-77 and CWE-94, where insufficient validation of user-supplied data leads to unauthorized code execution. From an operational perspective, this vulnerability is particularly dangerous because it requires only local administrative credentials rather than external network access, making it exploitable within the context of an already compromised administrative session.
The technical implementation of this vulnerability stems from inadequate argument validation within a specific CLI command interface that governs line card operations in Cisco NX-OS environments. When an administrator executes a particular command with maliciously crafted arguments, the system fails to properly sanitize or validate the input before passing it to the underlying Linux operating system. This failure creates a pathway for arbitrary command execution that operates with the highest privilege level available to the line card component. The vulnerability's exploitation requires a valid administrator account, which aligns with the principle of least privilege but still represents a significant escalation risk since the attacker can execute commands with root-level access to the line card's Linux environment. The attack vector is particularly concerning because it leverages legitimate administrative functionality to achieve unauthorized code execution, making detection more challenging and the attack harder to distinguish from normal administrative operations.
The operational impact of CVE-2019-1769 extends beyond simple privilege escalation to potentially compromise the entire network infrastructure that relies on affected line cards. Attackers who successfully exploit this vulnerability can gain complete control over the underlying Linux systems of line cards, potentially allowing them to modify network configurations, extract sensitive data, or establish persistent access points within the network infrastructure. This vulnerability aligns with ATT&CK techniques related to privilege escalation and command execution, specifically mapping to tactics such as privilege escalation through exploitation of software vulnerabilities and execution through legitimate system tools. The implications are particularly severe in enterprise network environments where line cards often handle critical traffic processing and security functions. The vulnerability's presence could enable attackers to disrupt network operations, steal confidential information, or create backdoors for future access, making it a high-priority target for threat actors seeking to maintain persistent access to network infrastructure.
Mitigation strategies for CVE-2019-1769 should focus on immediate patching of affected Cisco NX-OS software versions, as Cisco has released security updates specifically addressing this vulnerability. Organizations should implement strict administrative access controls and monitoring of CLI activities to detect potential exploitation attempts. Network segmentation and privilege separation measures can help limit the impact if exploitation occurs, while comprehensive logging of administrative commands can provide forensic evidence of attacks. The vulnerability highlights the importance of input validation in system design and aligns with security best practices outlined in frameworks such as the OWASP Top Ten and NIST cybersecurity guidelines. Regular security assessments and vulnerability scanning should include checks for similar input validation flaws in network operating systems, as this type of vulnerability commonly affects complex network infrastructure components where privilege escalation opportunities exist. Additionally, implementing network access controls and monitoring for unusual command execution patterns can help detect exploitation attempts before they result in significant damage to network operations.