CVE-2019-5425 in Networks EdgeSwitch
Summary
by MITRE
In Ubiquiti Networks EdgeSwitch X v1.1.0 and prior, an authenticated user can execute arbitrary shell commands over the SSH interface bypassing the CLI interface, which allow them to escalate privileges to root.
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Analysis
by VulDB Data Team • 05/29/2020
The vulnerability CVE-2019-5425 represents a critical privilege escalation flaw in Ubiquiti Networks EdgeSwitch X series switches running firmware versions up to and including v1.1.0. This vulnerability specifically affects the SSH interface implementation and demonstrates a dangerous bypass of the intended command line interface security model. The flaw allows an authenticated user to directly execute shell commands without proper authorization checks, effectively circumventing the normal CLI access controls that should restrict administrative privileges. This represents a fundamental breakdown in the principle of least privilege that is essential for network device security.
The technical implementation of this vulnerability stems from improper input validation and command execution handling within the SSH daemon component of the EdgeSwitch X firmware. When users connect via SSH and attempt to execute certain commands, the system fails to properly sanitize or validate the input before passing it to the underlying shell execution engine. This creates a command injection vector that bypasses the normal CLI filtering mechanisms. The vulnerability is particularly concerning because it operates at the SSH layer rather than through the traditional CLI interface, making it harder to detect through conventional security monitoring approaches. The flaw essentially allows an authenticated user to escalate their privileges from a standard user account to root level access without requiring additional authentication factors or exploiting separate vulnerabilities.
From an operational impact perspective, this vulnerability creates a severe risk for network infrastructure security. An authenticated attacker who gains access to the device through legitimate means can immediately gain root access and execute arbitrary commands with full system privileges. This enables a wide range of malicious activities including but not limited to data exfiltration, network reconnaissance, lateral movement, and persistent backdoor installation. The vulnerability affects network administrators who may have been relying on the assumption that SSH access would be properly controlled through the CLI interface. This creates a false sense of security where legitimate users believe their access is appropriately restricted, while the underlying vulnerability allows for complete system compromise. The impact extends beyond individual device compromise as the compromised device can serve as a pivot point for attacking other network segments, particularly in environments where network switches are used as core infrastructure components.
Mitigation strategies for CVE-2019-5425 should focus on immediate firmware updates from Ubiquiti to address the specific vulnerability in the SSH implementation. Network administrators should also implement additional security controls including strict SSH access restrictions, monitoring for unusual command execution patterns, and regular security audits of network device configurations. The vulnerability aligns with CWE-78 which describes improper neutralization of special elements used in shell commands, and relates to ATT&CK technique T1059.001 for command and scripting interpreter. Organizations should also consider implementing network segmentation to limit the potential impact of such compromises and establish robust monitoring for shell command execution across network infrastructure devices. Regular vulnerability assessments of network equipment and maintaining up-to-date security patches remain critical defensive measures against similar flaws in network device implementations. The vulnerability highlights the importance of comprehensive security testing of network device interfaces and proper input validation mechanisms to prevent unauthorized privilege escalation attacks.