CVE-2018-5314 in NetScaler ADC
Summary
by MITRE
Command injection vulnerability in Citrix NetScaler ADC and NetScaler Gateway 11.0 before build 70.16, 11.1 before build 55.13, and 12.0 before build 53.13; and the NetScaler Load Balancing instance distributed with NetScaler SD-WAN/CloudBridge 4000, 4100, 5000 and 5100 WAN Optimization Edition 9.3.0 allows remote attackers to execute a system command or read arbitrary files via an SSH login prompt.
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Analysis
by VulDB Data Team • 02/16/2023
The CVE-2018-5314 vulnerability represents a critical command injection flaw affecting Citrix NetScaler ADC and NetScaler Gateway appliances across multiple versions including 11.0 through 70.16, 11.1 through 55.13, and 12.0 through 53.13, alongside specific SD-WAN/CloudBridge instances. This vulnerability specifically targets the SSH login prompt mechanism where attackers can exploit improper input validation to inject malicious commands that execute with elevated privileges on the underlying operating system. The flaw stems from insufficient sanitization of user-supplied data during authentication processes, creating a pathway for remote exploitation without requiring authentication credentials. The vulnerability is categorized under CWE-77 as a command injection weakness, which aligns with the broader category of injection flaws that represent one of the most prevalent and dangerous classes of vulnerabilities in network infrastructure devices. This weakness allows attackers to manipulate the command execution flow of the system, potentially enabling arbitrary code execution, data exfiltration, or complete system compromise.
The operational impact of this vulnerability extends far beyond simple privilege escalation, as it provides attackers with a direct pathway to execute system commands with root-level privileges on affected Citrix appliances. Attackers can leverage this vulnerability to perform remote code execution, access sensitive system files, modify configurations, and establish persistent backdoors within the network infrastructure. The vulnerability affects critical network security appliances that typically serve as gateways, load balancers, and application delivery controllers, making them prime targets for attackers seeking to establish footholds within enterprise networks. The attack surface is particularly concerning because these appliances often sit at the boundary of networks and may have access to internal systems, potentially enabling lateral movement attacks once initial compromise occurs. According to ATT&CK framework, this vulnerability maps to T1059.001 (Command and Scripting Interpreter: PowerShell) and T1068 (Exploitation for Privilege Escalation) techniques, demonstrating how the vulnerability can be leveraged to achieve persistent access and escalate privileges within compromised environments.
Mitigation strategies for CVE-2018-5314 require immediate implementation of vendor-provided patches and updates, as Citrix released security updates addressing this specific vulnerability. Organizations should implement network segmentation to limit access to affected appliances, particularly restricting SSH access to trusted administrative networks. Additional defensive measures include implementing strict input validation on all authentication interfaces, deploying intrusion detection systems to monitor for suspicious SSH login patterns, and conducting thorough network monitoring for anomalous command execution activities. The vulnerability also highlights the importance of maintaining up-to-date security patches across all network infrastructure components, as delayed patching creates extended attack windows for threat actors. Organizations should consider implementing privileged access management solutions to reduce the attack surface and limit the potential impact of such vulnerabilities. Regular security assessments and penetration testing of network infrastructure components help identify similar vulnerabilities that may exist in other systems, while compliance with industry standards such as NIST SP 800-53 and ISO 27001 provides structured approaches for vulnerability management and remediation. The vulnerability serves as a reminder of the critical importance of secure coding practices and input validation in network security appliances, particularly those handling authentication mechanisms that process user-supplied data.