CVE-2019-5424 in Networks EdgeSwitch X
Summary
by MITRE
In Ubiquiti Networks EdgeSwitch X v1.1.0 and prior, a privileged user can execute arbitrary shell commands over the SSH CLI interface. This allows to execute shell commands under the root user.
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Analysis
by VulDB Data Team • 05/29/2020
The vulnerability identified as CVE-2019-5424 affects Ubiquiti Networks EdgeSwitch X devices running firmware versions 1.1.0 and earlier, representing a critical privilege escalation flaw that enables authenticated users to execute arbitrary shell commands with root-level privileges. This vulnerability specifically targets the Secure Shell (SSH) command-line interface implementation within the network switch operating system, creating a pathway for malicious actors to gain unauthorized administrative access to the device. The flaw resides in the improper handling of user input within the CLI environment, allowing a privileged user to bypass normal access controls and escalate their privileges to the root user level. This represents a significant security weakness in network infrastructure equipment that could potentially compromise entire network segments if exploited by attackers with legitimate access credentials.
The technical exploitation of this vulnerability involves leveraging command injection mechanisms within the SSH CLI interface where user inputs are not properly sanitized or validated before being processed by the underlying shell. When a privileged user executes specific commands through the SSH interface, the system fails to properly isolate the user's input from the command execution environment, creating opportunities for arbitrary code execution. This flaw falls under the Common Weakness Enumeration category of command injection vulnerabilities, specifically CWE-77 which encompasses improper neutralization of special elements used in commands. The vulnerability allows for direct shell command execution, enabling attackers to manipulate system files, install backdoors, modify network configurations, or extract sensitive information from the device. The root privilege escalation aspect means that any authenticated user who can access the SSH interface can potentially gain full control over the device's operating system and network functionality.
From an operational impact perspective, this vulnerability poses severe risks to enterprise network security infrastructure, as network switches serve as critical components in network architecture and often contain sensitive configuration data and network access controls. The ability to execute commands as root user allows for complete system compromise, enabling attackers to modify routing tables, disable network monitoring capabilities, redirect traffic, or establish persistent access points within the network. This vulnerability can be exploited by attackers who have already gained legitimate user credentials through other means such as credential theft, social engineering, or weak authentication practices. The impact extends beyond individual device compromise to potentially affect network-wide security posture, as compromised switches can serve as entry points for lateral movement attacks within the network infrastructure. According to the MITRE ATT&CK framework, this vulnerability maps to techniques involving privilege escalation and command execution, specifically covering T1059 for command and script execution and T1068 for exploit for privilege escalation.
Mitigation strategies for CVE-2019-5424 should prioritize immediate firmware updates from Ubiquiti to address the underlying command injection flaw in the SSH CLI implementation. Network administrators should implement strict access controls and authentication measures including multi-factor authentication, network segmentation, and regular credential rotation to minimize the attack surface. The principle of least privilege should be enforced by limiting SSH access to only necessary personnel and implementing role-based access controls that restrict users to specific operational functions. Network monitoring should be enhanced to detect unusual command execution patterns or unauthorized access attempts through SSH sessions. Additionally, organizations should conduct regular security assessments of their network infrastructure to identify and remediate similar vulnerabilities in other network equipment. The vulnerability highlights the importance of secure coding practices in network device firmware development and underscores the need for regular security audits of critical infrastructure components. Organizations should also implement network access control lists and firewall rules to restrict SSH access to trusted network segments and establish robust logging and alerting mechanisms to detect potential exploitation attempts.