CVE-2016-4965 in FortiWan
Summary
by MITRE
Fortinet FortiWan (formerly AscernLink) before 4.2.5 allows remote authenticated users with access to the nslookup functionality to execute arbitrary commands with root privileges via the graph parameter to diagnosis_control.php.
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Analysis
by VulDB Data Team • 11/01/2024
The vulnerability identified as CVE-2016-4965 affects Fortinet FortiWan appliances running firmware versions prior to 4.2.5, representing a critical remote command execution flaw that can be exploited by authenticated attackers with access to the nslookup functionality. This vulnerability resides within the diagnosis_control.php script and specifically targets the graph parameter, which processes user input without proper sanitization or validation. The flaw allows an attacker to inject malicious commands that are subsequently executed with root privileges, effectively providing complete system compromise. The vulnerability stems from improper input handling and lacks adequate input validation mechanisms, creating an attack surface that can be exploited through the web-based administrative interface. This represents a classic command injection vulnerability that can be leveraged to gain unauthorized access to the underlying operating system and execute arbitrary code with the highest level of system privileges.
The technical implementation of this vulnerability demonstrates a failure in input validation and sanitization practices, where user-supplied data from the graph parameter is directly incorporated into system commands without proper escaping or filtering. This flaw aligns with CWE-77, which describes improper neutralization of special elements used in a command, and more specifically with CWE-94, which addresses the execution of code from untrusted sources. The vulnerability operates through a command injection attack vector that enables an authenticated user to manipulate the nslookup functionality and execute arbitrary system commands. The attack requires only basic authentication access to the appliance's administrative interface, making it particularly dangerous as it can be exploited by insiders or attackers who have obtained legitimate credentials. The root privilege escalation aspect of this vulnerability means that successful exploitation results in complete system compromise, allowing attackers to modify system files, install malware, or exfiltrate sensitive data.
The operational impact of CVE-2016-4965 extends beyond simple unauthorized access to encompass complete system control and potential data breaches. Organizations relying on FortiWan appliances for network security and WAN optimization face significant risks when running vulnerable firmware versions, as this vulnerability can be exploited remotely by authenticated attackers. The compromise of such appliances can result in network disruption, data exfiltration, and potential lateral movement within the network infrastructure. Attackers can leverage this vulnerability to establish persistent backdoors, modify network configurations, or use the compromised appliance as a pivot point for attacking other systems within the network perimeter. The vulnerability also impacts compliance requirements, as it creates an uncontrolled access point that can bypass security controls and monitoring systems. Organizations may face regulatory penalties and increased liability exposure when such critical vulnerabilities exist in their network infrastructure components.
Mitigation strategies for CVE-2016-4965 primarily focus on immediate firmware updates to version 4.2.5 or later, which contain the necessary patches to address the command injection vulnerability. Network administrators should also implement additional security controls including access restriction to administrative interfaces, monitoring of suspicious command execution patterns, and regular security assessments of network infrastructure components. The implementation of web application firewalls and input validation controls can provide additional defense-in-depth measures to prevent exploitation attempts. Organizations should conduct comprehensive vulnerability assessments to identify all instances of affected FortiWan appliances within their network infrastructure and prioritize remediation efforts based on risk exposure. Regular patch management processes should be implemented to ensure timely deployment of security updates and prevent similar vulnerabilities from being exploited in the future. The vulnerability also highlights the importance of principle of least privilege, where administrative access should be restricted to authorized personnel only, and multi-factor authentication should be implemented to reduce the risk of unauthorized access to critical network infrastructure components.